Ugh! I feel like we're really close to a solution here. For what it's worth, the times that mine dies seems to be on decell after it's hot. My car is a lot like Boss'. In town trips to the store etc. I had to quit taking her out on the twisties because I'm afraid she'll get me killed.

It's definitely heat. I can hear the gas gurgling as I sit and wait for it to cool.

BTW, my car is bone stock.

 

As mentioned above, I sent emails to Walbro, Racetronix, and to Aeromotive. Aeromotive has yet to respond but I have received messages from the other two. Here are their replies:

Racetronix
Q: I have a 1989 Firebird with the TPI/MP fuel injection setup. A bunch of us with similar cars have been experiencing a vapor lock-type issue during the brutal heat. After an hour or so of driving, the pressure will fall off to the point where there isn't sufficient pressure to power the car. Wait 15-30 minutes and I can start up and drive off for a few miles until the problem appears again.

We've all tested and replaced stuff trying to figure this out. My question is simple; I suspect the Edelbrock 17933 fuel pump I use is failing under the heat. Does your GSS340M pump have such a limitation? Can it handle the 110* heat index and run for more than an hour with the E10 fuel?

A: The EB 17933 appears to be a Walbro pump so our GSS340M is unlikely to solve your problem.
There is a good chance this problem is not pump related. Have you run a fuel pressure test?
These cars are known to have injector issues which can cause this.

R: Yes, I have run a FP test MANY times. I'm not saying this pump is the cause, but the fuel pump in general does seem to be the common denominator. My injectors are Venom 30lb. The pressure will hold for the previously stated time frame. The length of run time varies directly to heat: i.e., I test at idle with the hood both open & closed; open hood nets longer run time than closed. Road test nets about 75 minutes. I've wrapped the fuel lines inside the engine bay as well as the underside of the fuel tank. We are grasping at anything that may help us with our cars.

**He then asked me what kind of FPR I am running, I answered and have yet to hear back

Walbro
Q: 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/67gph 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. Let it sit for 15-30 minutes and you can crank it up and drive off for a few miles until the problem returns. 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?

A: Thank you for your inquiry and for purchasing our fuel pumps! I am sorry to hear that you are having issues with it. We definitely sell to Summit and Edelbrock and it cross references to our GCA758-2 kit (F20000169 pump). I don’t know of any issues with this pump as of late, but I can tell you for a fact that hot weather has a definite impact on pump performance. Between the fuel heating up in the system and the heat from the pavement the gas can actually boil in the tank. If it gets hot enough it will begin to vaporize and the result of that is a pump that is essentially running dry. I’m assuming you have this on a hanger assembly as well. Newer modules/applications have buckets that help keep the fuel pump constantly submerged. Being that it’s on a hanger, you will want to make sure to keep your tank at LEAST a ¼ full at all times. If it’s less than that, the fuel can slosh around the tank and the pump could be running dry at times.

As far as recommending a different pump, it really wouldn’t matter in this case. Any pump that you put in a hot fuel situation will have the symptoms I suggested above. Of course there could be many other possibilities (i.e. clogged filter, debris in the tank, fuel type, etc…). If you have any additional questions please let me know. I know I didn’t really give you a solution, but I hope this helps a little bit.

I tend to discount the Racetronix answer as the reply directly from Walbro contradicts what he said. So unless Aeromotive or another company has a magic solution, the pumps are going to get hot and sputter. Perhaps the solution lies in a better fuel tank with another method of keeping the pump submerged in cooler fuel? Although the answer seems a bit clearer, it wasn't the answer I was hoping for. I also think that the almost nationwide extraordinary heat wave might explain the larger number of complaints about this problem this year. I have read about it in previous years, but had yet to have it affect me. My conclusion is that as the weather cools, less of us will have the problem showing up. If next summer isn't such a scorcher, we may then revert back to a "regular" number of complaints the board seems to get each year.

 

The other option you can try is the 4th gen plastic gas tank and their "bucket" assembly for the fuel pump. Maybe try a GM factory LS1 style fuel pump, because its 110 deg in texas and my LS1 Trans am has no issues for HOURS and it constantly runs 210 deg coolant temp. I've been 3 hr drives in this heat and no issues.

I agree alittle with racetronix, it may not be pump related too. Theres always that chance. The under hood temps is the clear giveaway. The cooler underhood temps leads to longer run time. That could mean an electrical issue somewhere with heat, OR it does mean the fuel is heating up alot more and overheating the tank and thus causing the pumps to have issues. So it can be pump related, and then again it may be something else.

Can you try some ice packs on the return line? Whats the surface temps of the return line back to the tank, near the rear wheel well?

 

The ice wouldn't stand a chance! I don't know the temp of the lines, but they are certainly warm. My exhaust dumps before the axle so everything around there gets a bit toasty. After wrapping the underhood stuff, I'm kind of out of options as far as that area of the car goes.

I like the 4G tank option because it could potentially be a big improvement over replacing the 3G stuff with things we know are failure prone. I can easily find 4G F-bodies littering the salvage yard, although most are V6s. I'm reading up on it now.

EDIT: Wow, that's quite a chore. No drop in job there (never is, is it?!) I'll keep that in mind. Again, thanks for your continued advice Orr.

EDIT #2: Got a quote on why that may still not work, and why it does work on the LS1 cars:
"...As for the fuel line routing in the header area great point this was the biggest pita I had to deal with. Normally I would never even consider running a fuel line so close to the exhaust but as you said barring running it literally through the frame there is not a lot of options. The one good thing about these fuel systems is at least its a one way trip for the fuel once its past the filter at the back so its not like the exhaust can heat up the whole tank of gas...".
(post came from here: https://www.thirdgen.org/forums/ltx-...dgen-fuel.html)

 

I really think your problem is having a high flow pump. The excess volume of hot gas returning to the tank is heating up your fuel in the tank. Components in reguar pump fuel will start to change form (gaseous form) at ~120 deg F. Combine that with the pressure drop of the higher flowing pump and you have cavitation. Centrifugal pumps will not pump air or vapor and a loss of pressure is the result. FYI fuel in the rail upstream of the fpr is under pressure and will remain a liquid until sprayed by the injector. But the tank is at or about atmospheric pressure. Go back to the stock volume pump ~22gph I believe. I'm sure your problems will be solved.

 

Also, my stock 5.7 tpi runs all day on pump gas in 100 deg weather. Sitting in traffic too. No problems whatsoever with fuel pressure

 

Stock pump won't keep up with my 30 lb injectors, nor will it support the 350fwhp I'm looking for.

 

Well, my 4th gen tank was kinda bolt in, but the hard part was the lines. I am no longer using the factory hard lines. With braided, you have alot of options how to route the fuel lines, ie away from exhaust as much as possible. You can buy the quick snap-fit connectors to the top of the fuel tank assembly, like this:


You can adapt -6an lines/fittings to that and either cut/flare the hardlines for some tube flare to an adapters or just run line to the fuel rails. Problem is 15 of line isnt that cheap.

Now the factory stuff on thirdgens has rubber lines that just slip fit with a little flex wire clamp thing. That MAY work for the 4th gens too. I dont know what 4th gens use to adapter to the hard lines, but I figure its the same thing. I'd have to look at my trans am to see.

4th gen tank has no baffles in it, so the pumps sit in a "bucket" to keep fuel from sloshing around and the pump going dry. Seems to work well if you keep enough gas in the tank

 

Hi,
I had similar problem last year.I had wallbro F20000169 pump.When I was coming to home car stops(luckily I had enough speed that car rolls to garage door)When it have cooled I tried to start and it starts.I made test and hooked fuel pressure gauge to rail,and after ~40 min runtime car stops.Before it stops fuel pressure start to drop,and ~20psi it stops.
After that my friend and I replaced pump to Wallbro GSS 340M model(Racetronic)
That new pump solved problem,but car has some problems when starting it at hot weather when it has driven longer trips and if tank is below 1/2.It won't start at first try(pump whine is also higher sound)
I think there is these issues:
-when tank is not full and hot weather high volume pump heats gasoline(it actually boils in tank if I opened tank cap when tank is low and car is driven longer trip)
-stock location of muffler is not best(under gas tank...)
edit:Next I'm going to add some exhaust wrap over muffler,and see if that helps.

 

I took my car out today in 90* and got about 20 minutes in before the pressure started to flux. Got it parked, did my errand and put 1/2 a tank of gas in and that got me home.

I had been talking with Racetronix about their Walbro pump. They referred me to Greg Carroll at Blowerworks (supercharging company); they say he's well versed in TPI cars. He gave me some more things to try. He, Me, TGO, we all agree heat is our problem. I told him my voltages did not drop and he suggested a few things:

-->pinch the rubber return line when the pressure starts to drop:
*if you get a large jump in psi, the regulator may be the culprit
*if you get nothing, he then suggests checking the in-tank rubber hose; said if there a fracture in the rubber, it will open up when it gets hot and your pressure will drop; replace the pump if no fault with the hose is found

He also said the Walbro pumps are a good unit. Also said to get better submersible fuel hose (suggested Gates).

What's odd is that when an issue similar to this occurred in 2007, it was the pulsator that went bad. I removed it and installed a second Walbro with the hose supplied from Edelbrock. These symptoms remind me of the trouble I was having then. I had hoped I wouldn't have to drop the tank, but I think I've arrived at that point now (after the pinch test of course).

 

I just changed my fuel pump today to, a bosch, i sure hope i dont have this problem now gah.. -.- why couldnt i have read this sooner, my exaust is right below the tank as well, and i've been having a problem with it puttering and dieing out, i want to drive it to get it tuned up and alligned after having done ALOT to it, and im afraid to drive it to far haveing these issues, i hope it was my pump, and the problem is resolved though. i'll try n keep u guys updated if i find a fix myself.

 

Btw theres only 1 rubber ring that goes around the top of the tank to seal the sending unit in the tank. The other rubber ring was probably for another car/application..

 

https://www.thirdgen.org/forums/tpi/...regarding.html

Check this out, I am having same problem, a mechanic told me today was the way my exhaust was set up, not breathing right overheating the gas tank. causing vapor to reverse into the injectors. He is going to put it up on a lift this week and check it out. Oh do you have a Cat box? This threat I added, looks like a lot of these cars have the same problem.

 

NOTE: I am updating this post as well as the other one we're all reading

A week or so ago, I mention a couple of tests a fella at Blowerworks had me perform. He said to pinch the return fuel line and see what happens. What happened was really nothing. I got no spike in fuel pressure, thus eliminating my regulator as the source of my pressure loss. Couple that with my voltage tests a couple months ago (which yielded no voltage drop) and the fact that my entire underhood system is wrapped, and that leaves only one area that can fail. That is the submerged rubber fuel line in the tank.

I replaced that 4 1/2 years ago when the pulsator failed. Somehow or another, the hose has degraded or the clamps have come loose, thus resulting in the pressure loss. We all know about what E10 does to rubber; we all know that when something heats up, it expands. So if I have a crack in the hose due to E10 or whatever, then as the tank gets warmer, the crack opens more and loses more pressure. What's worse is that when my car is just past warming up (which is when I did the this test), I had no pressure jump when I clamped the return hose. Apparently, my problem exists ALL the time and is exacerbated to the point of failure when it gets hot. One would think that I'd be able to spot the issue rather quickly when I pull the sending unit out of the tank. If that's not the case, then a new pump & hose will both be going in.

Odd considering everything I've done to avoid dropping the tank has led me to the fact that I'll be dropping the tank in a couple weeks to examine the hose and pump assy.

I've been wrong just about every time I've prognosticated about this issue, but I'm running out of items to blame and have arrived at the last two (pump & hose).

Have any of you checked the submerged hose or pulsator (if you're still using it)?

 

I finally bit the bullet and dropped the tank; much easier the second time (in 4 years).

I had to laugh at myself this time though. Only took me 3 hours to get everything removed and have the tank strapless sitting on a jack stand. I know I had gotten most of the fuel out but could still hear the liquid-in-a-metal-container sound when I knocked on the bottom. I laid under the car for a good 30 minutes staring, wondering, worrying how I'd get the jack stand out from under it and not have it crash on my head or break the neck off. I eventually scooted a second stand under the right side and gradually eliminated the original one in the middle. Teetering on the edge of destruction, I thought. I laid on my back and edged the second stand out of the way, fully expecting the worst. It dropped onto the diff (a big honkin' 12 bolt mind you) and sat there. I lifted it up and it weighed next to nothing; manuvered it off the diff and it practically fell out of the bottom of the car...all in less time than it took you to read my description. Wow.

My secret was that when I did this last, I couldn't for the life me get it to go back in, kept getting stuck in the hole in the quarter panel. I got pissed enough to where I took my trusty channel locks and rolled up the rusty piece of metal over the hole. About 1/2' x 6" section. It popped right into place then, and fell right out this time. I won't cut a hole from the inside but I have no problem moving PITA oxidized metal out of my way.

So anyway, I removed the sending unit and inspected everything. Nothing looked broken, no tears in the rubber, no scum on the bottom of the tank, nothing. I have finally run out of things to blame (good thing because I haven't been right yet) and pieces to replace. I've order the Racetronix FPA-019 (another Warbro) pump that Orr has had success with. I may get it sometime next week and I'll let you know how it turns out.

Only thing I can think that may have hurt this pump is when I was wiring up the EZ-EFI to the FP relay, I had accidentally hooked the EZ ground wire (which I thought was a 12v source like the stock ECM) to the power terminal where the former stock ECM went. Started the car that first time and got nothing (obviously). Could putting ground in place of power have hurt it?

The pics below are:
1) tank so clean you could eat out of it
2) the hose that I thought would have been compromised but isn't
3) the fuel sock which doesn't really look too dirty

 

After much consternation and consideration, it was a faulty fuel pump after all.

I still can't understand how, when I have a big upgrade on this car, faulty parts show up and cost me six months of track-down time. A couple years ago, I installed AS&M large tube runners and could not get the car to idle, it had a massive vac leak. Turns out one of those $400+ runners was warped. This time, I installed an aftermarket fuel injection system and lose the fuel pump on the very first day I take it out for a test drive. Sometimes I think this hobby will drive me insane. For now, I'm happy.

A couple threads prior in this post documents my efforts to have a dialogue with Walbro regarding the '169 pump in regards to either heat or perhaps some other known issue. Mr Christians said there was none and I accepted that. I later stumbled upon a post by the TPI board moderator linking me to the same type of issue related to GNX Buicks. Same damn problem. I brought this to Mr Christians' attention and he said he did recall the problem but the faulty pumps were made during a period in early 2007 (mine was made 24106, late 2006). I gave him all of the details surrounding my problem and, to my surprise, he agreed to replace the faulty pump n/c. I do not believe Mr. Christians was hiding anything, moreover I don't think he correlated the Buick's problem to my car. I was specifically mentioning heat, not the real problem of a loss of fuel pressure. I have sent him my faulty pump for diagnosis and have asked him to report me the results.

It did take me almost six months to get to this point, so the opinion I'm about to render should be taken with a grain of salt. I do not think heat was the primary culprit; that would be the faulty fuel pump. I believe that when the fuel got even slightly warmer, it further hindered the pump from doing it's job. Keep in mind that I did pinch the return line while it had full pressure and got no spike in pressure at the gauge.

I took the car & new '169 pump out for a shakedown over the weekend, drove on the highway, on main roads, and a couple extended idle sessions for a total of 2 hours without so much as a hiccup. Air temp was in the 70s; I let the water get to 202 and back as well. Believe me, my eyes were glued to the o2 reading waiting for that inevitable spike-lean which never came. The o2 corrections being made did not show that gradual enrichening coupled with spike-lean, rather the corrections were marginal showing a constant, predictable pattern thus letting the driver stop worrying. I was also having a bouncy idle problem which never showed it's face again. The car just purrs and feels as solid as ever.

I, for one, am proud to use Walbro pumps and appreciate the company standing behind their product when an obvious malfunction occurred.

 

Congrats! Glad you found the issue and dropped that tank to fix it! Hopefully you have no further issues