Fuel pressure... where should it be?
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Joined: Jul 2001
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Fuel pressure... where should it be?
I got curious from another post so I checked mine out tonight. With the car off, I turn the key on w/o starting, and fuel pressure pumps up to 38-40. As soon as I hear the fuel pump relay snap, it drops right down to 20, then slowly drifts down even further, to about 14 after about 5 minutes.
This is with the new Accel injectors, new fuel filter, and a new fuel pump. The pump is a lifetime warranty, so what I'm really wondering if maybe the checkvalve is a leaker and I should cash in on a new pump. It also doesn't start like it used to with the old pump, takes longer. I really had to crank it after sitting for a couple of days.
Also, I installed a BBK AFPR, and the damn plenumn is hitting the adjustment bolt.... anyone else have this problem?
This is with the new Accel injectors, new fuel filter, and a new fuel pump. The pump is a lifetime warranty, so what I'm really wondering if maybe the checkvalve is a leaker and I should cash in on a new pump. It also doesn't start like it used to with the old pump, takes longer. I really had to crank it after sitting for a couple of days.
Also, I installed a BBK AFPR, and the damn plenumn is hitting the adjustment bolt.... anyone else have this problem?
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Joined: Sep 2002
Posts: 91
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From: Johnson Kansas
Re: Fuel pressure... where should it be? (mooncricket)
You've got a system leak somewhere. In my case is was the fuel pump checkvalve. My regulator bolt hit the plenum also but where I finally found that it ran the best it barely cleared. I think 38 -42 is stock pressure.
Instructor
Joined: Jun 2002
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From: cedar springs mi
Re: Fuel pressure... where should it be? (mooncricket)
i've read in the tpis hints book that the higher the fuel presure the better they showed an increase in performance from 40 to 50 i have accel 24lb injectors in mine and i'm running mine at about 47lbs in their diagram they showed a injector at about 30 or so and i't weas like a squirt bottle on stream and at 50 it was like mist mine also stayes right about at 47 running to :) :)
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Joined: Jul 2001
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Re: Fuel pressure... where should it be? (jjmac_dragracing)
i've read in the tpis hints book that the higher the fuel presure the better they showed an increase in performance from 40 to 50 i have accel 24lb injectors in mine and i'm running mine at about 47lbs in their diagram they showed a injector at about 30 or so and i't weas like a squirt bottle on stream and at 50 it was like mist mine also stayes right about at 47 running to :) :)
I got the TPIS book too. I thought the diagram at 30 psi was a little unfair, because this pressure isn't likely. I guess they were trying to make a point though. The plan is to play with the fuel pressure but I think I have to get rid of the leak and get a shorter bolt for the regulator. I'm thinking checkvalve in the fuel pump is the culprit
Racer
Joined: Jul 2001
Posts: 443
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From: Tampa FL
Re: Fuel pressure... where should it be? (mooncricket)
Mines set at 48 with stock injectors. I also went with a shorter bolt to clear the plenum. You could also have a bad FPR. Check pressure with the stock one just to make sure.
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Joined: Jul 2001
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Re: Fuel pressure... where should it be? (BOBA VETT)
Mines set at 48 with stock injectors. I also went with a shorter bolt to clear the plenum. You could also have a bad FPR. Check pressure with the stock one just to make sure.
you know, now that I think about it there was a pretty good sized pitted portion of the outside ring of the regulator that faces down. Maybe that's the leak?
Thread Starter
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Joined: Jul 2001
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Re: Fuel pressure... where should it be? (FSTRNU)
It could also be an injector leaking. I have heard that accel injectors are prone to dribbling sometimes quite excessively
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Joined: Dec 2000
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From: SE NY
Cruise-In II Veteran
Re: Fuel pressure... where should it be? (mooncricket)
If you have an '85-'88 Vette the cold-start injector could be leaking.
Also the AFPR diapharm could be leaking.
If you quickly clamp the fuel feed line near the FP it will isolate the FP check valve. Clamping the return line would isolate the AFPR diaghram.
Also the AFPR diapharm could be leaking.
If you quickly clamp the fuel feed line near the FP it will isolate the FP check valve. Clamping the return line would isolate the AFPR diaghram.
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Joined: Dec 2000
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From: SE NY
Cruise-In II Veteran
Re: Fuel pressure... where should it be? (mooncricket)
You can get an elimination kit but then you need to change the EPROM to do cold-start enrichment through the other eight injectors.
You could send the 9th injector to Rich at Cruzin Performance to be reconditioned and leak tested.
Also, if you isolate the leak to the injectors you can further isolate it to the problem injector. If you disconnect all injectors and the dist then prime the fuel rail a few times and crank the engine the wet spark plug should isolate the bad injector; if all are damp with fuel suspect the cold-start injector.
You could send the 9th injector to Rich at Cruzin Performance to be reconditioned and leak tested.
Also, if you isolate the leak to the injectors you can further isolate it to the problem injector. If you disconnect all injectors and the dist then prime the fuel rail a few times and crank the engine the wet spark plug should isolate the bad injector; if all are damp with fuel suspect the cold-start injector.