1989 Firebird Formula TPI

Four years ago I replaced the stock fuel pump due to a faulty pulsator (which I eliminated) with an Edelbrock/Warlboro 67 gph unit, which has run flawlessly until I replaced the stock engine harness & ECM with the EZ-EFI system.

That pump is the subject of my issue and question. In short, it will run between 40-85 minutes and then the pressure, almost abruptly, falls off and the car dies. For the time the car is running, it will start at cold idle w/ 36psi (44 WOT) and eek it's way down to 32psi at it's hottest point, shortly before totally giving up, which takes about 15 seconds to go from 32 to 10 or less.

Let me give some background as nothing here is stock. I did make the switch from the stock ECM to the EZ-EFI system, which works great. The wideband O2 really helped me diagnose the fuel pump quickly. With that, the EGR is gone and the charcoal canister was eliminated. The tank used the stock gas cap and the former canister purge line now runs from the sending unit through a rubber line, into the pressure release valve (formerly beside the canister) and out through a small length of hose by the filler neck. Kind of venting where a true vented gas cap would. My exhaust is true dual and dumps before the axle.

The conditions surrounding the issue have been documented pretty thoroughly. After driving in 95*+ heat for a couple days, the car would die after about an hour of spirited driving, once leaving me to find a tow home. I tightened up the headers which seemed to help part of the problem. I took it out and twice more the car died after the same time frame. While it idled, I hooked a pressure gauge up to the rail and noted the pressure decline, the shut-down interval was the same. However, with the hood open, I couldn't get it to stall. I closed the hood and moved it out in the sun and it died w/in 50 minutes. Water was about 215 each time the car died.

I called Edelbrock (pump dealer) and apparently I stumped every tech in the room. Eventually the fella said that heat is not an issue for these pumps and that my tank may not be breathing properly and to try using the stock gas cap (was using a pre-vent style Stant cap). I tried, it stalled again (warm restart) after 40 minutes. The vent line is letting vapors out, I can smell them and they are warm. When I remove the cap, I get the woosh of warm smelly vapors exiting the tank. I do not hear any liquid burbling nor do I hear the tank itself expanding or contracting. I have tried running the car without any gas cap and get the same results

What I've noticed is after letting the car cool, I will get successively more line pressure at prime. 5 minutes of cool down will get me 20 psi, 2 hours 30psi, overnight and I get the full hour (wow!) of run time. The low-pressure prime exhibits a higher pump whine sound note than normal. Full pressure and it sounds normal. With the car off, any pressure in the tank begins to decline almost immediately. With KOEO and prime, it will hold pressure for about a minute and then slowly begin to decline.

I'm concerned and may well be wrong, but please set me straight.
-w/o EGR, is it getting so hot that exhaust is heating the pump or vaporizing the fuel in the rail?
-could my pump be getting too hot?
-is my ventilation setup correct?
-please don't tell me I need to replace the pump again!

 

Thats just weird. What level of fuel is in the tank, and does that make a difference in run time?

 

Man I wish it was that simple. I get the problem on <1/4 tank and completely full.

 

Maybe a hole in the rubber line connecting the pump to the fuel line? That would count for your bleed-down condition.....

 

Could be. I'll chalk that one on the "Drop The Tank" side of my advice tally.

Drop The Tank - 1
Other Issue - 0

Unfortunately, if I were reading this from someone else, I'd tell them something in the tank is amiss. What I can't figure out is the timing. Car ran like a champ on the dyno for an hour or so and had 2 twenty minute interstate trips to and from the the dyno with the old setup, only a couple days before I took it out in favor of the EZ-EFI setup.

 

can you log pump voltage and note what happens when the car gets hot?

If its losing pressure, it sounds like its losing voltage...and if its doing this when hot, it could be a wiring problem as heat can change resistance in wiring.

 

I would think I can, however I'm unsure how to go about it. The ALDL is not in service with the new system; I have a multimeter, I guess this would be hooked up to the relay wires somehow?

My ECM supplies ground, so I'm assuming that would get the (-) probe and the orange wire (12v power supply) or tan/white (pump power) gets the (+)?
EDIT: it's the tan/white and a chassis ground

 

Not sure, but any way you can get a voltage reading and watch what it does while its running and right before it dies will be helpful. If the ecm is cutting power to the pump, then you found your problem. I dont think its the pump since it worked before with the stock ECM. This new system is doing something thats causing pump to fail.

If voltage does not drop, then its a pump problem more than likely...assuming the regulator and such are in working order.

 

Ok, thanks Orr. I'll work on that.

 

I tested voltage on just about everything, and made a few more observations. Some of my notes may be duplicated from above. Here's what I found:

I tested Relay Wires A, C, E, with the ground being the shock tower for all tests.
Wire.......Before Startup.......Running...........After Pressure Loss
C...........12.0 constant........13.64 steady.....12.16 steady
E............12.19 constant......12.8 steady......12.28 steady

Wire A I had hooked up for the entire run:
At cold prime, 11.2
Upon cold startup: 36psi, 13.82
7 min elapsed: 35psi, 12.80 (full warm idle)
30 min elap 35psi, 12.76 (203* water temp)
45 min elap 34psi, 12.81 (214*)
50 min elap began pressure loss, 12.75 steady as pressure fell (219*)

When pressure got around 5psi, I killed the car. It would idle, however just barely; throttle tip-in made the car stumble. I opened the hood to see if cooling down would help, which it did not.
-my O2 was pegged lean
-opened vented gas cap, no effect
-turned on both fans, no effect
-bungeed relay above hot engine in mid air, no effect
-with car on, pressure would rise, fall a few psi, rise, and fall to 5psi where I kill the car
-above 18psi, voltage is steady; while it falls below that, voltage gets steadily higher (peaks around 13.8)
-I can hear the pump whine (while the car is running) above 18psi, below that I cannot hear it
-I'd let it rest for a few minutes, prime and get 20psi which would hold while the key is on, would start a slow decline almost immediately upon key off
-turn the car on after that and get 30psi which would climb to around 34 and within a minute, begin it's descent
-some hot primes got no pressure at all althought *I think* i heard the pump

The Rear Connector
-the wires by the tank were just barely warm after almost an hour of idle run time
-the front face of the fuel tank was pretty hot
I probed the white and purple wires, black is ground and always 0, I grounded the circuit to the frame for all tests
Car cold, KOEO prime
white: 12.1 prime, 0 after prime closed
purp: 6.8 constant
Car Hot, KOEO prime
white: 12.3 prime, 0 after prime closed
purp: 7.03 constant

If I use the knowledge Orr stated above (or perhaps common sense), I'd say my pump may be the culprit. I'm not totally sure, so I'm going to do a little more research. If anyone has any more opinions, please weigh in.

 

I just noticed you have venom injs.. When the shop i worked @ started selling them we had a lot of people return them because they leaked down and caused all kinds of problems.
Id pull them out, set them in the road or better yet, tape them on the railroad tracks and watch them get smashed all while ordering a good set of injs from any of our board sponsors or ford motorsport.
And I have to ask... Y did you ditch the stock computer?

 

Sorry you've had a bad experience with the Venoms. I've had them in now for almost 4 years, so far they don't seem to be an issue. I would assume that if they were leaking, my O2 wouldn't register a total lean out and I might have a backfire issue as well. If I'm wrong, please let me know.

I swapped out the stock ECU for the EZ-EFI system because I wanted newer technology controlling my engine. I like the *almost* self-tuning capability and the info the handheld gives me.

 

might be the pump if its getting extremely hot. Not sure tho, since i never felt the tank after run time to see how hot it gets.

 

I also agree, this seems to be a fuel pump issue. But maybe not the pump itself. If you replace with a new pump, you may have the same issue. Question... why does the fuel get so hot. I suspect you may have a cavation problem within the pump caused by the heat. Your voltages look fine, I would check the current draw. You can tell how hard the pump is working by the current (amps). fyi.. the more the pump moves fluid(volume) the higher the current reading. Has nothing to do with pressure. If your pump is cavitating(unable to build pressure and move fuel) the current should be low. I would monitor this and report just like you did with the voltage. My question is, what is causing the fuel to get so hot?

 

Maybe a quick easier method to determine if the fuel temp is the issue. Let the tank run low ~ 1/4 or less. Run the car till you have the same low pressure problems. Quickly fill the tank with fresh fuel. This will rapidly cool it down. Does the problem go away for while till it heats up again?

 

The temperature issue is probably my biggest question outside of the timing of the failures immediately after I installed the new system (and removing the EGR).

I got some Boom Mat, resistant to 400* direct/continuous and 2000* radiant and applied it to the bottom half (anywhere I could touch) of the tank. Interesting results. I got it to idle for 50 minutes (hood closed) before the pressure started it's descent, when it hit 20 psi, I killed the car. In previous experiements when I'd open the tank, there was a HOT rush of vapors. This time, I opened the tank and felt WARM vapors, and less of them too. The tank still felt hot, but the vapors were telling me the wrap did it's job. I came back out to check the gauge after a 30 minute cool down and noted it had gained 10 psi. Weird.

I tried another experiment with the hood open and I removed the heat shield under the tank (no muffler, no worries!). My theory was the raised combustion/underhood temps were causing an issue in the rail. Idled it this time for an hour and fifteen (1:15:00-which was the longest time I could DRIVE the car before it died) before it depressurized. Funny after-thought though, I released the fuel pressure (<20 psi) on the gauge into a small tank; all I got was a tiny trickle of liquid fuel, not even enough to really roll through the plastic tube.

I suppose it might well be the pump, but I'd like to find an explanation as to WHY the temperatures at the tank and underhood effect these changes in runtime; could that even be a coincidence? Even, what could I have done to hurt the pump while I was hooking up the EZ-EFI. Yes, I was working with the pump relay..no idea though. Still not quite ready to drop the tank.....investigation is half the fun, right?

 

Motoking, not sure how I'd monitor that. Moreover, which wire in the relay and what setting on the DMM should I be using?

Thanks for your input too.

 

My bets are on heat being the culprit.. and caused by??? The tank pressure issues are interesting, but you said in your first post you ran the car without the cap and resulted in the same symptoms. It sounds like some heat may generated from your exhaust, but you've run this setup for ~4 years with no issues right? If it was me (and I'm glad its not) I would check and remove the filter on the pump (in the tank), temperarily. If there is restriction and a drop of pressure great enough, with the right amount of heat, cavitation will occur. I would forget about that current (amp) test for the pump. I haven't pulled a tank out in while, and I can't remember, but does the return line exit right near the pump inlet?

 

I believe it exits at the top of the tank, where the sending unit is..but I'm not really sure.

Yes, the exhaust has been like this for almost 5 years now.

The heat is what I'm thinking too. With the hood being open and that buying me 20 minutes more of run time, I'm guessing that may be giving me a vapor lock situation (or something akin to that). I've toyed with the idea of using the same heat wrap and doing the fuel rails. Weird how I got hardly any fuel from the pressure gauge after it choked itself out. But let's say it is a vapor lock, wouldn't the pump continue to send fuel thru the rail and maintain some sort of pressue?

You'd think FAST would have a bunch of these issues documented if this kit resulted in this situation often enough; that said, I can't understand what is so different about my car.

EDIT: I called FAST and asked the tech about this. He said they haven't had any related issues, nor does he think EGR removal would make it SO hot underhood so as to cause a vaporlock-type situation. Also said he though it would have to be "pretty hot" to cause an in-tank issue. Couple that with what the Edelbrock guy said (pumps aren't generally affected by heat) and I'm left with a bunch of coincidences and no real idea of what to work on.

 

Well how hot are underhood temps getting?? what are your header temps at?

 

I can't say for sure. I was mentioning the temps because I'm thinking the EGR removal is going to be the only thing that would raise them. Also the extra run time when the hood is open is curious. I don't have a temp gun, just eyeballing the wire loom that is melting over the header (I know that sounds stupid, but it didn't do that before).

 

Is your FPR working correctly?

 

Yes, it works. When I was setting up the EZ-EFI, I adjusted it to 44 psi at WOT.

Let me ask this, I remembered yesterday that I did have to mess around a good bit with the relay. Most of the work was done with the battery disconnected. Some of it was not done that way. The EZ system uses a ground signal from the ECM, as the stock ECM uses a voltage signal. I had erroneously hooked it up with the stock ground in place and the EZ-ground wire in place of the stock voltage wire (2 grounds, 1 ground signal on a voltage dependent wire). I wonder if this may have hurt my pump?

I eventually figured it out and ran a 12v switched in place of the stock ECM wire and now have the EZ-ground in place of the stock ground wire in the relay.

 

Eric,

Does you exhaust dump out under the car or out to the sides, maybe it is overheating the gas tank. If you are doing multiple trials in the driveway rather than driving, you're not giving the car a proper chance to cool. I am concerned that all we do is cook our gas tanks / fuel pumps when tinkering in the driveway.

 

It dumps under the car, just before the axle. I'm pretty sure it's doing at least a little heating of the tank area. However, my new heat shielding has helped that some, as noted above.

My car has the issue both while I'm on the road and while I'm in the garage. I am doing the bulk of the testing sitting still because a) it happens faster this way and b) I don't wanna have to get towed home again.

I have come to the conclusion that I just need to wrap the hard lines and fuel rail in that 400* boom mat; heat has been the only constant in all this and judging by the location of everything, I'd bet that if this doesn't solve the problem, it may help considerably.

 

I wanted to make sure everyone who was following this post got to see my "resolution". This reply is a duplicate of the one I posted here:
https://www.thirdgen.org/forums/tpi/...regarding.html
_________________________
In an earlier post, I stated I was going to wrap my engine compartment fuel lines and hope to fix the problem. The short answer is that it did not work. Below are the details of this attempt.

As previously noted, I wrapped the bottom of the tank with Heat Reflective Mat, the results noted in that post. I removed the fuel rail and wrapped it completely (except for the top of the regulator) in HRM, including the connections for the hard lines. I also wrapped the 2 hard lines that reside under the alternator, the rubber lines, and the hard lines back to where they pass by the header. The metal connections at each different line set were left unwrapped. Obviously, my theory was that insulating them from engine heat would cure the problem.

I tested this fix as I have the others: in the garage, with the hood closed, FP gauge attached, WBO2 reading at hand. The difference this time is I put 2 box fans on HI about a foot away from the front of the car so as to give some effect of moving along the road. Admittedly, testing during this heat wave may not have been ideal, but I wanted to be sure that, should this work, it would definitely have been the answer. Those conditions are:
-air temp @ start 96*, heat index 113*, 36 psi on the gauge
-after 20 minutes, the water got to 193*, I turned on the AUX fan for the duration; the O2 correction went from a +7% down to a +3% until the test failed; water temp was 185*
-after 40 minutes, the pressure began to drop. air temp 102*, heat index 116*

Were I driving, I figured I would have gotten an hour of drive time before I had to call for a tow.

Someone above mentioned E10 as a possible cause of our problems. I have done some reading and I think he might be correct. I did not have this problem when the weather was 85* in May. These links have a ring of truth for all of us. I am by no means an expert and do not purport them to be the gospel. I think they contain bits of info that can help us (yes, one is about boat engines), however if any of it is true, I think until E0 is offered again, we may be in for a tough time.
http://www.thehulltruth.com/archive/t-192129.html
http://www.fuel-testers.com/list_e10_engine_damage.html
http://www.laboratoryequipment.com/u...H-Blending.pdf

I am beginning to think it is pure coincidence that immediately after I switched my EFI system, I got this issue. Even before I fired the car the first time, the temperature started hitting well over 90* on a regular basis. For the most part, here in Richmond, VA, we've had only a week or so of temps UNDER 90*since mid-May. I seldom drive the car for more than 30 minutes per engine start. I may run a few errands with a total time out and about of way more than an hour, but the conditions under which I was testing the new EFI were extreme (for me) so that I may verify and feel good about my results. I do feel that I could (and most likely will) continue to drive my weekend warrior on short jaunts around town as I had never encountered this problem until recently (my hour+ test sessions). My dyno trip for the new EFI will probably wait until the weather turns cooler.

Personally, I do not believe my fuel pump is at fault. This is purely E10 and one killer heat wave to blame. I think we all can go back to enjoying our cars in the fall and cussing the Powers That Be until then for the poison they put in the gas these days. But, as always, I'm open to another solution.

 

we could start a poll and see if people that live in consistently cold areas have this issue, if they dont, then outside heat is a contributing factor to the problem.

just an idea.

 

Hmmm i run E10 all the time and havent noticed a problem. My car was shutting off on me randomly but I chalked that up to tune problems and I havent had it happen since I changed out my fuel map. I worked the idle areas and other vacuum areas I never worked on before and it seemed to help. My stalling wasnt at idle tho, only after a quick rev up and when quickly stopping Not sure why that was the case.

And I can bet with my turbos my underhood temps get alot hotter than yours

I wouldnt rule the possibility out, but doesnt make sense that its E10 causing your issues immediately after swapping EFI. Thats a coincidence but to me it seems like a possible cause. Only way to tell is to run the stock system again

 

In the other fuel pump thread I'm in, I mentioned that I got 20 minutes of drive time today.

You echo what I've been thinking recently. Either I swap the pump out or swap back over to the stock setup. I figured something dumb may happen, so I kept all the stock parts, the stock ECM is still under the dash, the stock harness is still laying in the engine bay, right next to the new stuff.

I'm going to seriously mull this over. Soo sick of this.

 

I didn't mull it over too long. I swapped back in the stock setup today. Good thing I didn't start cutting and tossing after I got the EZ working. Took me about 6 hours, which was a day less than it took me to install the new stuff.

I was so spoiled by the heated O2 and the easier-than-this idle adjustment that lead to a better-than-this idle. Oh well, I'm sure my AutoXray is happy to be useful again.

I'm going to test it in the next couple of days; we're going to be pushing 100* and 110* heat index so hopefully I will have a better handle on this by the end of the weekend.

 

I got a chuckle out of your statement, Orr.

Got the car fired up with the stock setup, couldn't have possibly picked a hotter day to do it either. The outside heat index was 102*, the thermo in the garage where the test was taking place was near 110* with the car running.

I kept the hood open, but I know it got hot enough; the store-bought "fireproof" wire loom again melted, even after I tied it away from the header. I kept the car going for 90 minutes, intermittently turning it off to reset the idle. Water got over 200* but the fuel pressure only waivered with the oscillation of the idle. Until I can take it for a drive, I won't say the aftermarket fuel injection was the cause but it ain't looking good.

 

lol it sounds like you have some hot engine temps if your melting wires. How much timing you running and can you get a laser heat gun to measure header temps? Sounds like its running hotter than it should be for some reason.

But keep us posted on the stock EFI setup. I'm not sure why the EZ EFI would cause problems when warm if the stock one doesnt, but it will rule out one variable when you test it.

I just know that my fuel lines sit close to my downpipe and everything under hood gets hot and I run E10. The shock tower caps have melted and the paint on the wheel wells is crinkled abit, so I know its getting hot. My fuel lines are wrapped with heat insulation tho and another sheild over the lines to further restrict heat, but that doesnt stop heat from soaking the fuel rails.
Regardless, the car still runs good now that the tune is in order. It seems to run as strong when hot than it does when cool. Hard to say if the gas thing is an issue.

 

I don't know anyone w/ a laser heat gun.

I don't think my car is getting hotter than it's supposed to; I have a huge Be Cool rad, a 170* thermo, and manual control of the AUX fan; under normal driving conditions, I turn that fan on at 200* so i keep it close to 180 at all times. The headers were Jet-Hotted. Even my Honda gets hotter than usual in this extreme heat. I think it's affecting the Firebird too. The wires & stock loom are fine. It's the Advance Auto wire loom that can't handle it.

If it turns out to be the EZ-EFI, I'm gonna wonder WTH is so different.

I run 6* of base timing. On the dyno, it's the only setting that gave really good results. At the moment, I've been having trouble dialing in both the timing and the idle. Every time I get the timing where I want, it moves up a degree or 2 when I tighten the clamp. Grr. I had 8* yesterday. Oops.

I'm going to check for a vac leak (got an idle surge) and get the timing dead nuts on. It's also having a hard timing going into closed loop. That one's weird. Coolant over 180* + 110* air temp and open loop. I think once I get the timing dialed in, everything will fall into place.

 

I think my testing is complete, the results not what I wanted but I think I've figured out the bigger picture. Needless to say, this Firebird won't be running the Power Tour any time soon.

First, I want to mention that, yes, precise timing cures many ills. Like I mentioned, every time I'd tighten down the clamp, the distributor would move up 2* My solution was to get the right timing, turn the car off, (my dad got shocked once grabbing the top of the dizzy while the car was running) grab the distributor and hold it while I tighten down the clamp. Bingo, dead nuts 6. The O2 came on as it should and the idle I set was perfect.

So today's test was done in 94* heat. In total, the car was running about 90 minutes, with about 75 minutes being drive time. Had great fun getting that much road time. However, on my last pass I saw the AFR drop out and hustled the car home. Yep, it failed again. So, like the rest of you, I still have the mystery illness.

BUT....I have a few observations that I found interesting. As I was watching the O2, I found that when I let off the gas, it would drop to <20mv or even 0 for a couple seconds until it started correcting again. Never knew that. Once the corrections resumed, all was as it should be. I was hot, car was hot. Took it around side roads and 2 trips on the highway. At about the 70 minute mark (2nd hwy trip), I was cruising about 70 and noticed the O2 was holding 40mv. Yeah, 40..I blipped the throttle and got it back into the proper correction sequence. Scary as I'd hate for the car to cut out at highway speed with cars around me. I managed to keep it rolling off of the highway and 4 miles to my house where upon idle, the AFR promptly took a dive (around 20). I had maybe 2 minutes where I could gas it enough to keep it alive and back into the garage. Funny, the corrections were perfect so long at it was under load. Got home, coughed and died in the driveway.

The short answer is that it's not the EZ-EFI's fault. The hard question is why did it seem like I got progressively less drive time with the EZ and a much longer time with the stock setup? The temp has fluctuated a bit, however most every time I've tested either setup, it was around 95* or more.

I also noticed that FastChips has turned off my EGR and CCP functions. I got that from the "EGR duty cycle" and "CCP duty cycle" percentages on the scanner (which were both 0) OK, so not having EGR wasn't it. Not having the charcoal canister wasn't it. EZ-EFI wasn't it. Everyone that changed out fuel pumps has said that didn't fix the problem. This all leads me to one conclusion: more than likely, this problem has always been there and only during my recent "road testing" trips of over 45 minutes during the hottest days in recent memory, has it surfaced.

I've mentioned before that this car lives a simple existence: trips to the grocery store, trips to family & friends houses, trips to the car show. Always on the road for under 30 minutes at a time, always with at least a half hour break in between cranks, hardly ever in heat like this. Trips to the car show always had the hood up for hours cooling it off. Most of the longer drive times are in the spring, winter & fall when it's cooler. The dyno run was on a nice 85* in May with a huge box fan blowing on it while it ran for, you guessed it, about 45 minutes; a cool down period, then interstate travel into the garage. After I realized this confluence of logic today, I believe more than ever that it's always been there.

I still have no idea what is hurting our cars, but I do believe that somehow it is heat. I can't explain how Orr's twin turbo car merrily putts around town not showing the symptoms our cars do. I really really have no idea why it seems the EZ-EFI setup brings the symptoms on a little quicker. For the moment, I still have both harness's & both computers in the car, I can hook either up in a about a day.

I'm going to stick with the stock setup as I figure out how I'm going to proceed. I had envisioned (finally) getting around to the head/cam swap next year but right now I don't know. I personally don't feel like I need to solve this problem, just keep driving it as I always have. I know the folks who use their cars for a daily driver need this fixed. If I can help or test something, I'd love be of some use. If someone does fix the problem, I think we should all send him a $100 royalty check to show our gratitude.

 

Man thats crazy stuff. Got me confused. Even when my car was stock with bolt ons, and a daily driver at the time, I never had a problem like this. However my longest trip was only 1.5 hours drive in warm conditions but never a scorcher.

With the bolt on L98 with aftermarket walbro pump, i never had a problem in the summer but it didnt see long trips over 30 min. It never got over 185-190 deg for the most part either for water temps.

With the 383 I never had issues. BUT I did have this issue you describe here to some extent.
This sounds to me like its dropping out of closed loop. Are you running closed loop? When letting off the throttle you can enter deceleration modes which will drop the 02 out to near 0 mv. This is normal and OK. When cruising it should constantly be switching once its HOT and ready to read. If its not getting hot enough to be "o2 ready" then car may not get into closed loop or it may enter closed loop too early and give false readings.

My 383 did this with the heated o2 sensors too with long tube headers. At startup, on warm or hot restarts, i'd idle ok for a second then it would go lean and idle would get rough....start to die out on me. Had to blip throttle to keep it alive and read again. I think it was o2 sensor not ready. I eventually just tuned OPEN loop only and had a blast!
The last part you mention about running ok under load and then off the gas it took a dive...sounds like the idle gas temps are too cool for the sensor and its dropping out....May need idle tuning as far as timing and fueling is concerned.

Now with the turbo car, I got 2 intank pumps and stock wiring harness modded for speed density. Open loop tuning and no narrow band o2 sensor at all. No muffler over the tank and its a 4th gen gas tank with charcoal canister on tank, with the vent just piped to atmosphere.... I know it gets baked under hood. The exhaust parts are ridiculous but I took it out for several long cruises over a 45min or so length and really heated the thing up and have no issues with air fuel ratio changing. I've been impressed with it now that the tune is pretty good, but doesnt matter now its all changing again.

I run straight 93 oct with 10% ethanol mix like most ppl do. Lines are shielded and wrapped but I think its still getting hot. I know the fuel rails see high temps but I dont have data on that. Fluid in the intake is constantly 200-210 most of the time so the manifold is hot and so is the fuel.

 

It may be dropping out of CL, but I doubt it. From what I have seen, once it goes CL, it stays there unless it's super cold or I restart. It may have, but I didn't notice if it did. The AFR does the lean out on decel-to-idle with the EZ-EFI too, so I'm not worried about it. But to answer your question, yes, I run closed loop. I was monitoring the volts & the crosscounts for the entire trip yesterday, it was working perfectly until it reached the point of no return.

I'm having an argument in my mind over whether I should go back to EZ or not. I think if someone offered me enough for it, I'd sell it. I feel like I need to utilize it simply because I paid a good penny for everything. Most likely, after I let it sit for a month or so, I'll get the urge to convert it back over to EZ and hit the dyno. If the numbers wow! me, I'll keep it hooked up. If not or if I test it and still can't get the car to run longer than an hour, it's gone to the highest bidder.

I got an email from Tim (thanks for the note Tim!) who's been following my folly; said he bough an 89 Formula 350 (stock except for tune up essentials & new rad) and drove the f**ker from DC to Florida in this heat. After I stopped beating my head against the desk, I began to wonder if it could be aftermarket pumps? Hmm. I dunno. Anywho, you can chime in anytime Tim, if only to let us know that some of these car still can run when it's hot outside!

 

this may sound dumb but what octane fuel are you running? because when i bought my car the PO had lost the manual and he just said put regular gas in it. wrong. I had this issue too but not as extreme as some of you guys, but sure enough its supposed to be 92+ octane. I started running 93 and my cars performance has jumped alot and doesnt have this problem anymore. it might be due to the fact that higher octane has a slower burn and is less volatile, so maybe when the car gets real hot the fuel can withstand the heat before it hits the combustion chamber, which with regular gas it would vaporize before it hits the combustion chamber, causing un-ideal burning and wierd drivability issues.

this is just my theory and it has helped my car alot, so if you are running 92+ octane already, maybe try an octane booster additive to get it somewhere around 95+ and see how that turns out.

im not sure though, just a thought.

 

Hi Guys,

As I told Boss I just got back from a thousand mile trip bringing home with my '89 Formula 350 TPI. It was hot - DC to south FL down I-95. A/C on the whole way, cruise at 70mph mostly. Car was running what I believe is cold - 160 on the highway, no more than 200 in town. New rad and water pump. Not sure the thermostat. Anyways ran great and it's essentially stock.

I want to learn more about codes / diagnosing problems etc so I know what to do when they happen. I've been reading this and other threads and the amount of detail is incredible here.

Anyways if you want me to take some readings or I can help otherwise let me know.

Cheers

 

Oh and we ran 87 octane the whole way, did not pick up any pinging.
Tim

 

I run 93 octane. I wish it was as simple as getting better gas. An octane problem isn't going to decrease fuel pressure to the point where the car will stall. We have a pressure problem; were it an octane issue, I'd be complaining about knock & ping instead. Appreciate the input though!

 

For kicks, can you try force open loop and tune open loop as necessary to get air fuel in line and see if that makes any difference at all?

 

I have no idea how to tune. I send my chip to FastChips or buy EZ-EFI. The ratio isn't a problem until the pressure drops out.

 

I'm losing pressure, like bad, after recently replacing the fuel pump..I'm concerned about two things, I cannot remember if i used clamps to fasten the rubber hose you are referring to.......Another thing, the fuel pump kit came with two big o-rings. I used the smaller one, was I supposed to use the big one elsewhere?

Thanks.

 

Is anybody having any issues with the stock fuel pump ( I believe 22 gph) and the stock fpr? It seems like everyone with the high volume aftermarket pumps are having problems. This isn't the only thread documenting the same symptoms.

 

Red- if you didn't use clamps, then that may be one source for a pressure leak. Also, I do not remember where exactly the o-rings go.

King- I'd like to know the answer to that myself, the big-boy pump does seem to be in most of the posts. I know this post is but one of a growing number of people having the same issue. You'd think with all the folks out there fussing over this, that someone would know the Final Jeopardy Answer.

 

Last resort for you may be to try a new/different pump

 

I had thought of that, Orr. I am holding off due to the volume of folks that said they changed theirs and had no success. The other thing is, I can't really find another brand of pump other than the Walbro/Edelbrock I am using now. Got any suggestions?

 

What model walbro? I thought they made a few different kinds. I had the walbro kit from racetronix, the 340M pump. Worked ok for me. Not sure if those are the same pumps used in my twin pump kit, but they are working well enough now.

Could try to fit in the big bosch 044 pump. Its a 340lph setup, bigger than the 255 tho in size but I hear it drops in ok.

But then again if other guys have done that and still have issues, thats kinda surprising.

The run time length varying with the different electronics is intriguing to me. Kinda seems like its got something to do with the electronic circuit controlling the pump or main fueling if fuel pressure drops off. Stock system somehow allowed for longer run time vs EZ EFI? Just seems odd or maybe its a coincidence.

I wonder if theres another sensor that may have part in this problem, where it gets hot and fails, causing the pump to drop in pressure. I remember you saying the voltage didnt vary when it dropped off in pressure, meaning the electronics was doing it's part in getting power to the pump. The tank being hot seems like perhaps the pump is overheating itself, and why I was curious about trying a new pump. If others tried that and still have same issues, it may not be the problem. I cant really think of anything else.

This a MAF based car? Did/have you tried measuring the MAF sensor temps after driving around awhile? I briefly recall a guy having lean conditions after getting hot, and it was due to the MAF getting heatsoaked and throwing off the calibration. Once insulated/isolated from heat, it ran fine. It may be something similar with another electronic device somewhere in the system due to heat?

 

I guess technically it's an Edelbrock 17933, but I read somewhere it's a repackaged Walboro. It's the 67gph unit. I even called Edelbrock and asked them if heat was an issue with these pumps and they said "no". This pump MAY have close to 5000 miles, if that much. I actually removed a similar unit when I had the pulsator problem some years back and replaced that one with this one. I have that spare pump in the attic when/if I go to replace it.

I never saw another sensor when I took the sending unit it. To that end, after I heat wrapped the bottom of the tank, the vapors were much cooler; much fewer vapors to boot. I bet something's getting hot somewhere, but it can't be the fuel in my engine bay. Like I mentioned, mine are wrapped now too. I couldn't fathom that it's getting SO hot in the tank with about half of the system heat shielded. But, I'm missing the boat somewhere. I mean, obviously something's not working as it should. Remember, after it died out one time, I pressed the pressure relief on the FP gauge and got just barely a trickle of fuel. So, the fuel is not making it up to the gauge, which leads me to the belief that perhaps the pump IS getting too hot and cavitating or whatever that term is. Until the company can admit that their pump can't hang with our hot 3G's, we'll never really know. We need maybe a heavy duty or race-style pump that can stand the heat. I could certainly look thru Summit to see what they offer. I don't really want to replace this unit with another one like it. I'd like to attempt to make an upgrade from it at least.

Well, in stock form it is a MAF car. The EZ-EFI is SD-based and gives the same problem. That statement I made about getting less run time on the EZ unit may have not been well thought out. When I started with EZ, I was getting about 1h:15m of drive time, just like I did on the most recent drive with stock components. Sitting still, both units got around 45 minutes. I was complaining a bit because on the last EZ drive, I got 20 minutes of drive time. Man was I pissed. I believe that was on a fresh fill too.

I'm going to bite the bullet and (eventually) reinstall the EZ and simply wait out the hot weather. I'm going to tune and fight and dyno until I just give up and put the fawker back in the box. Hopefully it will produce such awesome numbers that I'll be back to trying to fix this issue. A good pump would be next.

EDIT: Orr, are you referring to your Aeromotive 11142-340 pump?
Double Edit: No you're not. I found the Racetronix 340M (FPA-019)

 

The band "Accept" had a song years ago about "write a letter. you'll feel bettah!" So I wrote an email to Walbro (man did I slaughter that spelling in the last post) and asked them this:

I own a 1989 Firebird with a 357sbc & TPI MP setup. I and many of my peers on my message board have been encountering an issue with a fuel problem similar to a vapor lock issue. The 255lph/65gph pump is a fairly common upgrade for our cars. I bought mine from Summit under the Edelbrock nameplate (their pn is 17933).

Our problem is that after an hour of driving in this super hot summer weather, our cars sputter out and die. The pressure will fall off and within about 2 minutes, there is not enough pressure to power the car. Voltages have been checked, fuel lines wrapped, pumps replaced, hair pulled out, but nothing can solve the issue.

Do you know of an issue with this pump and our 3rd generation F-bodies or the pump and heat? You would be a great hero if you could help us solve our problem. If not, would you be so kind as to recommend a higher performance pump that may be able to handle the heat better?

Thank You For Your Time Sir,
Eric Lastnamehere
Richmond, VA

If I get a response, I'll post it here.

EDIT: I also sent queries to Aeromotive about their 11142-340 pump and Racetronix about their GSS340M (Walbro) pump, asking similar questions. I'm inclined to attempt a pump replacement with the Aeromotive or the 340M that Orr uses. I think most of us have used either the Edelbrock 17933 or Walbro equivilant.