TecknoMike

I was actually able to perform this this test by accident two days ago.

I came to a stoplight at the second to last gas station before my house when I heard my fuel pump noise start going bonkers again and my RPMs fluctuating. I was able to make a right at the light and left into the gas station.
As I hit the gas the car lacked power and was backfiring through the intake. I noticed that after I completed the turn I was able to get a burst of acceleration, as if the gas in the tank swooshed around giving the pump some fuel instead of the assumed fumes. I made it to the pump with the engine about to die. I had around 1/4 tank of gas and filled it up. After filling up the car started up with no problem at all! I was able to drive back home with 0 issues.

Chevy86 IROC-Z

iTrader: (17)

One thing that is tough is finding an original owner who still has the vehicle. I attempted to locate a owner to ask if the fuel pump whine was common straight from the dealership. But I haven't been successful. The thread I created is lost and buried some where on the TGO server.

LilSki

iTrader: (1)

I'm going to add a but more fuel to the fire. I have a TPI conversion with an external pump that is mounted back by the tank. Last summer I took the car for a 40 min drive and it was in the 90s. At the halfway point the pump got very loud and I started to notice a stumble at idle. We got to our destination and the car sat in the sun for about an hour. When we went back to the car the pump was back to its normal volume and the miss was gone. After about 5 min it got loud again. I made it home but it was running like complete crap by the time I got there.

I have not reproduced this as I have been reluctant to take the car on long trips. I bought a factory EFI tank in hopes of fixing it but now I'm not so sure that will fix the problem. I just wanted to post about my non factory setup with an external pump and non factory Megasquirt computer having the same issue.

To me it seems to be a pressure/heat issue but I again I have not really spent much time diagnosing it.

VandykeT/A

My car runs longer on nice cool days (60 or colder) with pretty well a full tank. At 70 degrees and half a tank I get maybe 45 minutes. Has anyone tested the voltage going to the pump. I'm thinking about this something like the pass window motor on a 4th gen. Autotrix makes a kit that has a bigger power wire going to the motor. Low voltage causes it to heat and quit with time. Maybe out fuel pumps are doing this and the hot fuel is just a side effect?

T/Aperformance

I think you maybe onto something.
I know this isue is still going on and no one has seam to fix the isue.
The fuel vaper in the tank has alwasy bean there, The vaper is routed to the charcoal canister from there the canister purge valve allows the vapers to enter the TB, by the way this is an $18 part . THe computer monitors this and tells when and where to allow the canister to purge. Check your haynes manual its there.
Now I'm not sure if this is the fix for your problem. The pump wine gets loader becouse the added presure in the tank.
I've bean chasing this problem for some time now looking enywhere and everywhere replacing all different parts. BUt in my case a PO had removed the charcoal canister and purge valve.
OF course I'm now looking for a charcoal canister. Can't buy new. Unless someone can tell me how to go with out one and not have this problem

VandykeT/A

What is an 18 dollar part? I couldn't find a solenoid at the parts stores?

bubbagump2001

Would something like this help if it seems to be heat / pressure related? It would require to make an additional tap in the tank with a 90 degree fitting, some hose? But it would add extra volume for vapor to escape..

http://www.jjcraceandrally.com/Produ...20&%20Fittings

87350IROC

iTrader: (2)

No. Based on the recent evidence it seems apparent that this is a fuel temperature issue not a pressure issue.

87350IROC

iTrader: (2)

Low voltage does not cause electronics to run hot. Heat generated by electronics is from the power source. More power, more heat potential. Simple conservation of energy.

Chevy86 IROC-Z

iTrader: (17)

As well as the more current passing through a wire that is thin, the hotter the wire gets.

VandykeT/A

Well it was worth a shot. There has to be fix for this we're all missing. I've read on here people driving there car in 80 degree weather. I couldn't get 20 minutes from home on a 80 degree day. I know of 2 other TPI cars around here a 87 GTA and a 91 Z28 and 1 of them is daily driven and the other has never experienced this. It has to be something with the cars not fuel quality.If the tank wasn't venting right when I ran my car without a cap it wouldn't have died. I've replaced every electrical part except the alternator and I'm doing that tomorrow. Every fuel part is brand new and less than a month old, bypassed the canister completely. I just don't know what to do for this. I'm about to pull my hair out. Next step will be taking the fuel pump back out, changing it and making sure the sock isn't under the return line like was mentioned earlier. If that doesn't fix it as bad as I hate to this thing is sold.

Chevy86 IROC-Z

iTrader: (17)

What? If you can't figure out the issue your gonna sell the car? My IROC threw a rod, had it parked, while I was gone, someone sold my Camaro to a tow truck claiming that it was his with no title, found it in the junkyard, parts missing (tb, dizzy, whole tpi intake) bought a used block and did a complete overhaul. All that said, still have a few problems but she will stay with me till I'm ready to see the great gate in the sky.

Chevy86 IROC-Z

iTrader: (17)

Does anyone know if the issue happens to TB Injection (RS Camaro's)? Curious to know if the problem is only related to TPI only.

87350IROC

iTrader: (2)

You are still barking up the wrong tree. It is clearly fuel head related. Changing electronics will not do anything. Don't waste your money. Take a look at your under hood fuel lines and tell me how close they come to the headers.

87350IROC

iTrader: (2)

I have not heard of any. And I also assume the tbi cars do not run the fuel lines right next to the exhaust like the TPI cars. But I'm not certain.

T/Aperformance

Its not a solenoid its the charcoal canister purge valve.
The charcoal canister takes the vapors that have always bean in the tank and allows them to be be compusted in the engine instead of going off into the air. The purge valve helps control when the vapars are allowed ti enter the compustion chamber.
The fuel pressure and the heat that everyone is complaining about here has always bean in our car. every since the government said we could no longer let gas vapors to just go into the air. Emissions control.
What everone here is seeing has always bean there. Something must be wrong then at the point of how the vapors aren't getting to where they need to at the right time.

VandykeT/A

I had the problem before headers. And I did look at the fuel lines toward the back. I'm about 1.5 inches away from the back tube. How can we go about relocating the lines? And what about the brackets that hold the fuel lines that are bolted within just a few inches of the front header tube. I'm going to take heat tape and go all over the fuel lines and try to keep heat out anyway I can I just don't see as to why this wasn't happening in 89.

RBob

iTrader: (1)

Composition of the fuel has been changing every year for quite some time now. And the composition differs in some 100 separate regional areas.

I see it with the lawn tractor when I mow. Need to adjust the carb each and every time the gas can gets refilled.

RBob.

T/Aperformance

I don't see why No one is truly lissening here. The tank only vents into the TB so the fuel vapors can be burnt. The problem is NOW FOLLOW ALONG HERE!!!!! its so simple. the vent for the tank goes threw the charcoal canister that by the way is conected to the computer. From there it goes threw a purge valve. BY the way this maybe the broblem piece. Then into the TB. so it can be burned off.
IF there is a clog in the line, A bad charcoal canister or a bad purge valve then You will be having this issue you're discribine.
YES IT IS THIS SIMPLE!!!!

TecknoMike

I'm wondering, if it's simply vapors not leaving the tank, how did refilling my fuel tank immediately after dying out at the gas station from ~1/4 to full remedy (probably temporarily) my car dying out? I posted this story earlier.

87350IROC

iTrader: (2)

No. There is a secondary pressure release valve on the gas tank to prevent this from happening. Ever notice the short tube with the round valve hanging from the gas tank?

87350IROC

iTrader: (2)

Exactly. The methanol in today's gas lowers the boiling point. Making our problems worse. And may explain why even a stock vehicle today has problems.

ASE doc

I would ask the same exhaust question. I have seen a few cases where aftermarket exhaust was routed too close to the tank and the heat shield was not in place. The heat from the exhaust was nearly boiling the fuel in the tank. Be sure that the heat shield is installed on the tank next to the exhaust. I have also noticed in one case where the coolant temp sensor was defective and causing a rich fuel mixture, heating up the catalyst, which added to the hot exhaust.

I have also seen a few cases of heat related fuel pump failure. Use a fuel pressure gauge to monitor fuel pressure when this symptom occurs. If pressure is dropping off, replace the fuel pump.

Some pressure in tank, even with the EVAP system working, is normal. The fuel tank pressure control valve will maintain tank pressure of up to 1"Hg or 6.0kPa under normal operation.

TTOP350

iTrader: (8)

Because you were low on fuel and sucked air when you braked and or cornered. On older tanks there isnt a baffle and fuel will run away from the pickup strainer. Keep your tank above 1/4 tank and you won't have the prob.
Or you can put in a 91-92 tank and enjoy driving until your last 1/2 gallon of gas.

87350IROC

iTrader: (2)

TTOP,

We aren't talking about fuel sloshing. These 9 pages are dedicated the fuel overheat issue. My car died on the dyno with 3/4 tank after running continuously for over an hour. No sloshing on the dyno.

For TecknoMike, adding fuel helped because the fresh fuel brought down the temperature inside the gas tank.

TTOP350

iTrader: (8)

Yes, I understand. His died pulling into a gas station with less than a 1/4 tank. I'm sure the gas gauge is acurate.
These cars are old, there are going to be weird issues that we will have to find a solution for.
I guess I've been very lucky with mine. As soon as I found out about the baffled tanks (91?) I put one in it. I've put 240,000 miles on her driving all over the right side of the country. From IL to FL,TN, OH ozarks and many many trips to GA and back. All the "big trips" were in the hot summer. Never a problem.
Hooker (coated) long tubes, 3" strait back Y pipe (runs right under the fuel lines) and a SLP catback.
I have been following this thread from day one and I have noticed a lot of people are finding bad hoses/pumps, electrical/grounds and other weird stuff. Even with all I've read on here its tuff to believe that the heat of the fuel is causing everyones problem. Could it be? yes very much so but I doubt it. I just can't wrap my head around this problem. Its a nasty one.

87350IROC

iTrader: (2)

Yes it is a tough one. My plan of attack is currently in work. I am:

- installing '91-92 "baffled" tank
- new fuel pump
- make sure fuel return does not dump directly on pickup
- layer of insulation to bottom of gas tank
- header wrap on muffler
- getting headers / y-pipe ceramic coated
- modify fuel rails for rear entrance / exit

So I am going for the full hail mary. I never want to have this problem again. Like you, I want to road trip this car. But can't. I think the fuel rail modification will make the biggest difference. Get the lines away from the exhaust.

I suspect you have not had issues b/c you headers are coated.

Before I tore apart the car for the winter I took a bunch of temperature measurements of the fuel system as my car idled in my garage for 90 mins. In 45 degree weather the bottom of the gas tank was 100 degrees. That is getting somewhat close to the boiling point of the gas, depending on the formulation. I will see if I can find the data and post it up.

TTOP350

iTrader: (8)

I forgot I ran SLP uncoated headers/ypipe for many years. Prolly half of my road trips
All my heat shields are in place for the rear exhaust and my pipes exit the rear.

I just put a racetronix 255lph in a 29,000mile formula 350 2day.(no i didn't cut the car up, I dropped the tank and goofing off/eating lunch it took 5 hrs) The newer cars come with a big disc shapped plastic part that goes between the return line a the pump strainer. No idea why but could have something to do with the heat.

skibum2100

Like clockwork...when the outside of the metal tank reaches 124F my car dies. The fuel rail regularly reach 154F and all that hot fuel going back to the tank is the culprit. I have even added a "transmission cooler" to act as a fuel cooler for the return fuel (not even on the pressure side). Now I am waiting for a hotter day (90+) to test it and then, hopefully, post a band-aid fix...

Consider the boiling point of gasoline, get the temperature just .5 of a degree less and now have the fuel pump pull a vacuum at the impeller (effectively lowering the local pressure)...we get cavitation at the pump impeller and what should be liquid fuel moving over the impeller is now a gas that the impeller can spin freely in (and not pump fuel). Imagine a million tiny "air" bubbles around and inside the pump, these pumps are only made to move liquid not something in a gaseous state.

Why isn't this a widespread problem...it will be. Gasoline companies try to find the cheapest way to still let the planet's cars operate. They add more "additives" instead of proper gasoline chains (The chains from C7H16 through C11H24 are blended together and used for gasoline. All of them vaporize at temperatures below the boiling point of water. That's why if you spill gasoline on the ground it evaporates very quickly. from http://auto.howstuffworks.com/fuel-e...estion1051.htm). More additives means less "gas" in the gas.

Does anyone still have the factory paint on their fuel lines that goes behind the alternator. I wonder if that was a ceramic paint or coating...

Methanol...I ran straight "aviation fuel" (no methanol) last summer and had the same problems.

Anybody have ideas for a return-less fuel delivery system for a TPI?...LS1 cars have a dead-head to the fuel rail, maybe we could too.

87350IROC

iTrader: (2)

Yes. I have only had problems in the last year and a half. Gas keeps changing. I suspect when you ran the SLP's the gas had less/no methanol. All of my rear heat shields are there as well.

Here is my temperature chart on a cold WA evening, 40 degree ambient, maybe 50 degrees in the garage when I started.

87350IROC

iTrader: (2)

and beginning steps to convert fuel rail to rear feed/return. Here is a -6 bung welded to the output of the fuel pressure regulator. I have another -6 welded to the back of the driver side rail. And the front of the passenger rail is welded shut.

T/Aperformance

No I'm sory that is not a vent tube, That is a air intake one way filter. Not a vent filter. The EPA states that no fuel vapor is to be allowed to go outside into the air.
Now out fuel tanks are a sealed unit. Thats why we no onger have vented gas caps for our car.
When gasoline is under presure it heats up.And causes more vapors.
( ethenal does not make this worse, But helps raise the boiling point of gasoliine.)
I don't see why no one can see this as the problem, Is it just so simple that some how it doesn't make sence , but it does.
Come one get out your haynes manual its right there plane as day.
You're over thinking the problem,

ridecool

iTrader: (2)

I've had the same problem when I go up to Jacksonville and back. You said you wanted to look at a stock Iroc mine is a 89 vert with a 305 I did put headers on but everything else is stock. I also live in Orlando area let me know if I could be of any help.

VandykeT/A

I thought the thing hanging off the tank was a check valve. When the tank had so much pressure it opens and allows it to exit. I believe the problem is heat. When my pump is loudest (when the cap has been off) I can put my fingers down in the neck and feel the heat. I guess fuel system modifications are in order. Since guys with fuel cells and aftermarket external pumps have the same problem. It has to be something heating the fuel up front. I'm going to add header wrap, relocate the fuel line thats a inch away from a header tube, heat tape everything, ditch the brackets bolted directly to the hot engine, and add a tranny cooler in the return line.

87350IROC

iTrader: (2)

Sorry dude, you are wrong. I have one sitting in front of me right now. It is designed primarily as an intake but also as an exhaust in the event of evap failure. It is a safety device to prevent tank rupture. Its release pressure is higher than the evap working pressure so it is not normally in use but it is easily released buy simply blowing into it. Members have reported driving around with the gas cap off and still their engines died. It is not a pressure issue.

TTOP350

iTrader: (8)

Since heat is the issue, has anyone replaced the ICM, coil or pickup coil? These parts are subject to nasty heat just like the fuel/rails and are on the same time cycle.
I have read this whole topice but its been quite awhile ago soo if its been brought up I'm sorry 4 the repete...

87350IROC

iTrader: (2)

Yes, in fact I diagnosed the issue originally as ICM failures. Because, the car would stop running, but the time I replaced the ICM, it cooled down enough to continue driving. What made me convinced it is fuel related is when I had a failure on the dyno. Since it finally died somewhere with tools, I slapped a fuel pressure gauge on it. Fired it up, went to about 20psi and quickly dropped to below 10psi and died again. Range for about 10seconds max. 90 minutes later when the tow truck came, the car fired right up and drove it on the truck. When we got home, I checked fuel pressure and it was back up at 45psi. Definatley fuel pressure related.

bubbagump2001

Just a couple of thoughts. Has anyone put an in tank temp probe and drove around recording the changes? If so in theory when the tank gets hot if you would lets say pull into a car wash and hit the outside of the tank with cold water to drop the ambient temp of the tank in theory it should mimic the problem / solution without having to top off instantly and provide some raw data around this.. I had these similar conditions last year and had to replace, pump, sock, filter, cap, rotor, ignition coil, tank vent, wires and plugs before it totally went away. I've not had a 90 degree day yet with the high humidity to see if long term it resolved it.. Just trying to help...

VandykeT/A

New module and coil did nothing for mine at all. I've never changed the pick up though. I made it from my grandma's to my house (45 minutes ) and it quit again. About 25 minutes into the drive I started hearing the pump.

TTOP350

iTrader: (8)

Are these OEM pumps? aftermarket? age of the pumps? Has anyone had the chance to test the voltage at the pump during failure? What about swapping in a racetronix fuelpump hot wire kit??? Tried swapping the dizzy for a cool one? What kind of fans are used on the dyno? big little? big dyno area with lots of airflow? Has anyone changed the pump after the "noises" started? What about the old school fuel cool cans that held ice and a coil of fuel line?(may be a idea to try) As soon as I hear a funky pump noise I'm ordering a new one to slap in cause its only a matter of time. Most of the stock ones seem to get flakey around 120,000miles. Altho Ive had pumps run for 300,000K and I replaced them just because!
Some cars seem to be able to idle all day long with the AC and AC/DC cranking with 0 problems.. Some can't..
Again its been awhile since I read the whole thing, Just prolly throwing the same ideas out and I do understand that there is point that fuel does its thing.

RBob

iTrader: (1)

I think we mean ethanol, methanol is the stuff at the track for race cars.

The LS1 cars also run 58 psi to the rails to prevent the fuel from flashing to vapor. A return less system would be interesting. Since the stock ECMs can't handle the steady state fuel pressure, maybe put the FPR right before the engine compartment, get it off the engine.

This way a vacuum line to the FPR isn't too long. Then with some smaller injectors (and maybe some tuning), can also run higher fuel pressures.

RBob.

LilSki

iTrader: (1)

Isn't this how some modern cars do it? They have the pressure regulator back at the tank? So there is no hot fuel returning to the tank?

TTOP350

iTrader: (8)

Stand alone eletronic fuel psi control. These guys have some cool stuff and are about 20 mins away from me.

http://fuelab.com/fuel-pressure-regu...ure-regulators

T/Aperformance

I'm going to try and to explane the solution for this problem. You are all over looking. I had this problem and this is what finally solved it. It is the purge valveinline with the charcoal cannister. It is open. Not closing. Allowing fuel vapors to always enter the TB.
This is Not a heat issue. Take a good running third gen and check the temp of the tank with one that is having the problem The temps will be the same.
The purge valve is supposed to open and close at a certain vaccum pressure to allow fuel vapors to be burnt off.. If the purge valve is always open then fuel vapors will alway be entering the combustion prosses when ther are not suposed to. And the computer reads a to rich condition and leans out the fuel mixture. Thus giving us a vapor lock condition.
I had this same problem And after replaceing the hole fuel system in my car. ,tank, fuel lines, fuel rails, injectors, iac ,ECT. I finally read up on the charcoal canister purge valve and how it worked. I replace the purge valve and haven't had an issue since.
But since none of you believes this couls possibly be the problem. I ask the one broave soul out there to try this simple fix at a cost of less than $20. And give your results here.
Thank you

87350IROC

iTrader: (2)

I hear you. And it is entirely possible that that is the issue for some of the people here. That is not MY issue. How can you explain the drop in fuel pressure when it happens? How can you explain why it doesn't bother the engine until after an hour of running?

Does the engine go lean when it dies? Yes of course, but that is b/c the pressure is dropping, not b/c the computer is doing it. My very last dyno pull the engine was far leaner than the other pulls, right after the pull, the engine died. In full throttle, the computer does not have the authority to lean out the mixture.

With that said, I do have a new purge valve sitting in my pile of new parts to go in. I'm going with the scorched earth policy, changing everything.

RBob

iTrader: (1)

Yes, the LSx series have the regulator either in the tank, separate from the tank, or as part of the fuel filter.

RBob.

87350IROC

iTrader: (2)

Mine is a Walbro 255lph. About 4 years old and about 3k miles.

I have not tested the voltage. My replacement pumps will be dual Walbros with the hot wire kit.

No. But i have replaced the all the parts inside the distributor many times. At this point I'm confident my particular issue is not electronic. In the past I thought it was an ICM issue. I was carrying ICM's with me at all times. By the time I swapped out the ICM, the car cooled down enough to drive for a while longer. What finally convinced me it wasn't the ICM was the failure at the Dyno. I swapped the ICM right away, I'm getting really good at doing it. Had it switched in under 5 mins. Fired it up, and died about 10 seconds later.

Its a pretty standard dyno setup I would say. 24" fan or so and a pretty large area. Not a hot day, its never hot in WA. Car didn't have any problem staying at 180 degrees.

Mine doesn't make any noticeable noise, ever. Maybe its the dynamat in the car, but I never hear the pump. The cool can is a good idea, but our problems don't seem to show up until a significant amount of driving. So you would probably need to reload the ice a few times. Just adding some cold gas is probably easier.

LilSki

iTrader: (1)

I don't believe it is a vapor issue either with mine the more I think about it. I will see what happens this summer. I recently swapped out the old 305 and installed a vortec 350. And I did a little test today. I remember with the old 305 after about 30 min of driving even on a cool day my fuel rail would be hot to the touch. The same with my air tubes and intake. I ran the car today and felt the fuel rail when I got home and it was cool to the touch. The old style manifold has an exhaust crossover and the vortec setup does not and I don't run EGR. I have a feeling this will cure my issue since the intake/fuel rail won't be getting as hot since there is no exhaust crossover.

Chevy86 IROC-Z

iTrader: (17)

So what is this $20 part and where can I get it?

87350IROC

iTrader: (2)

He is talking about this guy.

http://www.amazon.com/ACDelco-214-20...3557229&sr=8-2