Fuel pump pressure loss, when warmed up
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Car: 88 firebird
Engine: 355
Transmission: t-5
Axle/Gears: 9 bolt 3.91
Fuel pump pressure loss, when warmed up
I'm guessing I should just replace the pump, but I don't know. When my vehicle warms up, the pressure on the pump drops. It was originally tbi, but I converted it to carb. I have a holley fuel pressure regulator, and when it warms up it's at 6psi, but cold it's at 9 psi. Also I should set the fuel pressure when the engines off correct? thanks in advance IT's an electric pump.
Last edited by tompumped; 09-17-2006 at 01:08 PM.
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Car: 88 firebird
Engine: 355
Transmission: t-5
Axle/Gears: 9 bolt 3.91
I replaced the gasket inside the pressure regulator, it seems like there's nothing to it, but I don't know. I guess I could clamp the hose for the return, I will do that tomorrow. Either way i'm going to replace the pump when I swap rears. Would a normal tbi fuel pump be more than enough for my application, i'm making maybe 375 horse? I never researched, but I don't see why i'd need a better pump if i'm dropping the pressure. Also I should set the pressure with the vehicle off correct? thank you
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Car: 88 firebird
Engine: 355
Transmission: t-5
Axle/Gears: 9 bolt 3.91
It's a cheap 3 port holley regulator. I forgot to mention that. I did what you said, and when I squeezed the return line the output line pressure dropped to zero. I don't know if that's normal, let me know. I appreciate it.
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Car: 89 Iroc & 88 Firecird & 86 Camaro
Engine: 350 TPI & 305 TBI & 305 Carb
Transmission: 700R4
When you squeeze the return line shut then the fuel pressure should spike or at least raise from 6psi. Sounds like it could be the pump, but I would make sure because these are not fun to change. I would make sure the pump is grounded good sometimes this will cause one to work slower. It also wouldn't hurt to install a new fuel filter, and then check pressure before the regulator like vader stated. Hope this helps
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Car: 88 firebird
Engine: 355
Transmission: t-5
Axle/Gears: 9 bolt 3.91
I know how much fun they are to change, but I haven't run the exhaust to the rear yet like I want, and I was going to swap rears. It's not that bad, I have other issues that are worse. I might just try that for now, I was going to wait till next year to swap rears. thanks
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Car: 88 firebird
Engine: 355
Transmission: t-5
Axle/Gears: 9 bolt 3.91
I was just looking at the regulator I think I have it hooked up wrong. I went to holley's website, and the regulators they show are different. I think I have an older design, on mine the inlet port is on the bottom, and there is two outlets on either side. I'm probably just going to buy a new one.
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Car: check
Engine: check
Transmission: check
I was just looking at the regulator I think I have it hooked up wrong. I went to holley's website, and the regulators they show are different. I think I have an older design, on mine the inlet port is on the bottom, and there is two outlets on either side. I'm probably just going to buy a new one.
Or plug one outlet with the other going to the carb inlet.
That regulator will work OK with the TBI pump. But not with a positive displacement pump such as used in high pressure systems.
RBob.
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Car: 88 firebird
Engine: 355
Transmission: t-5
Axle/Gears: 9 bolt 3.91
Yeah, holley makes them with the bottom port a return line now. This regulator has the inlet on the bottom and 2 outlets. Now should I run both outlets to my double pumper? I feel like an idiot, I never read what it said on the regulator, it worked fine for me on my iroc. I just replaced the gasket, and hooked it up the same way, but I put a gauge in line now. It's currently set up with one line as a return, when I squeezed that return line pressure did go up slowly, I didn't want to see how high it would go, but it went up to 7.5-8 psi. thanks, I guess I will replace the pump when I swap rears. I'm going to try and fine tune the idle today, as long as the pressure doesn't do the same thing. I also lost my secondary throttle stop screw, does anyone know if I will be able to order this? I didn't know how involved it was to fine tune a carburetor.
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Car: 88 firebird
Engine: 355
Transmission: t-5
Axle/Gears: 9 bolt 3.91
Anyone know if this is symptom of a bad fuel pump, or should I just replace the regulator with a newer design? Forget the previous questions.
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Car: 88 firebird
Engine: 355
Transmission: t-5
Axle/Gears: 9 bolt 3.91
Ok, I replaced the regulator with the proper one. A bypass regulator from holley. I still have the same problem, the pressure drops 3psi when warmed up after a couple of minutes driving. If I squeeze the return pressure will increase 6psi I believe, or almost 6, thanks.
I'm going to replace the pump anyway when I swap rears, but i'd like to know for sure if that's the cause. Thanks guys, peace
I'm going to replace the pump anyway when I swap rears, but i'd like to know for sure if that's the cause. Thanks guys, peace
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