2.8l Turbo fuel system issues

[Cidacious]

Will an adjustable FPR help solve my rich boost problem, or will I have to get a tune and a chip to do it? Also when the car gets really hot, it starts to putter and die, followed by a crank but a no start. The fuel/air ratio guage goes to 17.9 and then --- which, I believe, means no fuel then it dies. The fuel pump was replaced last summer with a holley 255lph one, but I guess it is possible that this one died too. I was kind of hoping that my current issue is caused by the FPR, and by buying an adjustable one, it may solve both issues. If it could solve the rich boost problem, how would I go about adjusting?

[RedZMonte]

start by putting a fuel pressure gauge on the fuel rail.. It sounds more like a bad fuel pump.. My walbro did the same thing when it got hot (Holley Pump is a Walbro).... once it cooled down it ran fine. I would start there, If your rich then i would think you don't want an ajustable FPR.... that will add more fuel not less. stock FPR is 1:1 iirc.. if your rich then you want to look more at tune or other fuel mixture items (good spark, O2 sensors, DEFINATLLY TUNE)

S

[Joseph Upson]

Not enough information, start from when the car was running fine then describe how the trouble started. Did you just buy the car recently with this problem, or did it develop. Ofcourse the best approach is a chip tune over an adjustable regulator. I guess it's possible but in my experience a bad fuel pump does not make the engine run rich at idle then suddenly lean up top, given that in order to do so it has to produce pressure equal to, or in excess of what it would at high rpm which is sort of backwards as they generally start out having trouble maintaining proper psi at idle.

What engine temp is the problem occuring at and after how much driving?
Is the problem consistent and can it easily be duplicated or intermittent?
What is your current fuel pressure? If it's too high it can certainly overheat the fuel pump as was mentioned.
Has any chip tuning been performed? There is a table that adds or pulls fuel based on engine temperature that could have been over adjusted as a safety measure due to the turbo.
There is also a table that pulls timing based on eng temp that can cause this problem, I had a bad chip update that put some data/values in the wrong places in the spark table once.
If there is a vacuum line leading to your current fuel pressure regulator is it connected?
Is the engine light coming on?
There was a rumor going around that counterfeit Walbro pumps are on the market being sold as genuine.
Make sure your fuel filter is fresh which I imagine you already have.

[Cidacious]

I had the car about a week when the fuel pump took a dump, or so the perf shop said (now out of business.) When he dropped the tank found that tank was empty when guage said 1/4 tank. When I bought car on the way home the guage worked fine and for about a week. Because up to that point it was trusted, I took it to the shop. I am thinking he already had the tank down so he said it was bad, when it really wasn't. But he did say that the fuel air guage meant it was too rich under boost sustained 10. I spoke with a GM tech over the weekend and he said not to run a holley pump even though it is boosted as it is not a race car. He said a holley is great for towing to the track for the weekend, not for putsing around town. He said a GM pump will do fine under boost w/ big injectors. Stock pump 14.4 gallons per hour. 50.8 PSI rated. Would everyone agree? The car runs fine at 10 on the guage, but the current drivability issue is 35 PSI at idle and when engine gets hot the car loses power considerably guage off the chart high, and frequent stalls. Under boost does not trigger service engine light, nor when there is the massive power loss. Fuel tank full/overflowing.

[Guest]

Give that GM tech a smack upside the head......

Holley in tank pumps are fine for driving around with in a grocery getter, they are just Walbro pumps, which have been known to be fine in OEM replacement and mild upgrade applications.

What car is this for? That will help to figure out what fuel system upgrades are needed, if any.

Joeseph, I'd love to live in your backwards world....

Anytime I have seen a fuel pump get weak, it will provide adiquate pressure, and volume at idle, but not at higher engine speed or load. Think about it, at idle an engine needs very little fuel to stay running, at higher RPM or load, more fuel is needed and is where a weak pump will show itself.

RedZMonte; an AFPR can be used to reduce fuel pressure, not just increase it. The Aeromotive FPR I have on my Datsun will go down well below where my engine will stay running, I think it's rated to like 20 PSIG on the low side. That being said, the use of an AFPR to reduce fuel delivery in an application like this is not recommended.

As mentioned, check the actual fuel pressure, not just at idle, but at different loads and RPM.

The best way to tune for a turbo set-up is to calibrate the ECM, and tune for YOUR CAR. This is the only way to have ideal fuel and spark delivery, and ensure a long life of your car, engine and replated parts.

35 PISG fuel pressure at idle is not something to worry about. With the vacuum line attached to the FPR, it should be around there or slightly higher at about 38 PSIG.

Pictures of set-up? There might be other reasons related to the install and not just the sum of the parts causing your problem.

[AleroB888]

Give that GM tech a smack upside the head......

Holley in tank pumps are fine for driving around with in a grocery getter, they are just Walbro pumps, which have been known to be fine in OEM replacement and mild upgrade applications.

Yeah, including 600 BHP grocery getters ?

Joeseph, I'd love to live in your backwards world....

Anytime I have seen a fuel pump get weak, it will provide adiquate pressure, and volume at idle, but not at higher engine speed or load. Think about it, at idle an engine needs very little fuel to stay running, at higher RPM or load, more fuel is needed and is where a weak pump will show itself.

I had two Walbros fail where they could not maintain pressure at idle, after the return line fuel began to heat up, yet pressure at WOT was close to where it should have been. That was in the early stages of failure of course, after which the pumps got weak in all ranges.
Part# F20000169 / example code: (06508-1)

There was a bad run of certain Walbros, but I suspect all of them don't function as well in the cramped confines of the venturi canister-type housing, where the ones I have used get finicky when the return fuel gets hot.

[Cidacious]

1988 Pontiac Fiero GT 2.8l 37,000 miles, Porsche turbo set at 7psi boost. Custom chip in computer (spot cut out of center rear console for easy replacement). Bigger injectors(don't know Ibs though). I need to get the car hot, in failure mode to read the pressure. Less than 500 miles/7 months on new holley pump and fuel filter.

[Cidacious]

When car is functioning it is at 35psi. I had a harbor freight special fuel pressure guage tester attached with teflon tape while driving. (I know I was begging for a fire....) It dropped to 15 PSI when the car was in the failure mode. If I let the car cool down for 15-20 minutes, when Priming pump I could get 40psi, but it would only last a block, then I had to wait in another parking lot. I had autozone check alternator and battery, both were fine. It would seem this is probably a fuel pump problem rather than an FPR problem right?

[Honest Don]

are you sure its really a going lean problem and not a misfire due to spark or overly rich conditions? A flooded out cylinder will read dead lean at the O2 sensor.

How close is the turbo/manifold to your distributor? It could be cooking the module.

[Joseph Upson]

1988 Pontiac Fiero GT 2.8l 37,000 miles, Porsche turbo set at 7psi boost. Custom chip in computer (spot cut out of center rear console for easy replacement). Bigger injectors(don't know Ibs though). I need to get the car hot, in failure mode to read the pressure. Less than 500 miles/7 months on new holley pump and fuel filter.

It's important to note that pump failure will not necessarily have a consistent presentation. Contrary to what raven remarked the nature of the problem will determine how it malfunctions, for example: overheat vs. worn journal bearing, vs worn brushes, vs. leaking casing seal. I'm speaking from my personal experience with failing fuel pumps not theory alone. A good pump and pressure regulator should not drop in pressure under normal conditions when the throttle is opened, the pressure should rise a little as the vacuum on the pressure regulator drops. When you apply 12v to the pump you should see normal range pressure. I believe 35 psi for the Fiero is about the low minimum. If it's dropping from there and you are sure the lines are okay replace the pump. GM Stock pumps are very dependable and will meet your requirements. The fuel gauge error is not uncommone in the Fiero either and it's possible it was aggravated when the assembly was removed from the tank. If you've starved the fuel pump several times that's a sure way to shorten the pump life. My first encounter with a bad pump was on my 4yr old car with barely 80k miles on it and the one thing I recall about the premature failure was running the tank low and starving it on several occasions taking corners kind of hard.

I've replaced more pumps than I can remember and had one take me over 600 miles before finally performing poorly enough for me to catch it with a pressure gauge, otherwise it only caused an occasional stumble on acceleration. I've had one overheat due to high pressure requiring me to pull over after several minutes of driving and another just blew a loop of the top o-ring out of the upper casing.

When a bad pump performs at higher rpm, it is not so much the pump improving as it is likely the ECM increasing the pulse width to maintain the proper air fuel ratio.

The problem can also be in your chip programming if the pump checks out okay. A datalog of engine performance would be helpful, that's what it took to identify a bad MAP sensor on my engine which did not set a code.

The GM Tech might be considering the amperage draw from the Holley pump if it is a high output part. There's no doubt it will perform but I bet there's a good reason behind his advice in your application.

[ghrarhg]

When car is functioning it is at 35psi. I had a harbor freight special fuel pressure guage tester attached with teflon tape while driving. (I know I was begging for a fire....) It dropped to 15 PSI when the car was in the failure mode. If I let the car cool down for 15-20 minutes, when Priming pump I could get 40psi, but it would only last a block, then I had to wait in another parking lot. I had autozone check alternator and battery, both were fine. It would seem this is probably a fuel pump problem rather than an FPR problem right?

I had similar symptoms when my FPR went on my turbo car. I was tuning/driving at the time, and the WB kept registering leaner and leaner no matter how much fuel I added. The car finally stalled out and I thought I was out of gas, but it kept letting me prime it/start it up and run a 1/2 mile or so before it would die. I didn't trust my gas gauge at the time, and I wasn't able to check fuel pressure on the side of the road. After I made it to the station and filled it with gas, the problem went away, but it still had about 1/4 according to how much I filled it. Confused, I figured my pump was shot or at the least the hose was loose in the tank and couldn't use the bottom 1/4. Unfortunately, I went through all the trouble of dropping the tank and pulling the fuel pump out etc, only to find it was fine. Replaced the FPR, and the problem went away.

Bottom line, the FPR is much easier to replace than dicking around with the fuel pump. I'd start there.

[Cidacious]

I had a harbor freight fuel pressure guage attached to the rail while driving so that I could better troubleshoot the problem. When the car would go into failure mode I checked the fuel pressure and it was reading 15psi. If I let the car sit for about 15-20minutes with the engine off, when I would go to prime it would read 35-40 psi, allowing me to drive about a block before it would fail and read 15psi again. Over the weekend I replaced the fuel pump (original was walbro, but was bought through holley for holley prices. It is reading 35-45psi, but I haven't been able to go on an endurance drive yet. I also did the fuel tank sending unit fix as listed on the pennock forum, bent the arm back where it should of been and now empty is truly empty and not 1/4 tank!!

[Cidacious]

Moved to boost section

[Cidacious]

Moved to boost section