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fuel pressure problem

Old 09-19-2014, 05:19 AM
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Car: Trans Am gta 5.7 1989
Engine: 350 tpi
Transmission: th700r4
Axle/Gears: BG 9 bolt
fuel pressure problem

hello

when i start my car its cranking a long time before its starts.
I have just checked the fuel pressure and with engine running the pressure is about 40 psi and when i turn it off it drops to 0. if i just turn the key(engine off) some times i dont get any pressure.

anybody know if its the pump or the fuel pressure regulator ??

thanks claus
Old 09-19-2014, 11:52 AM
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Car: 86 Monte SS (730,$8D,G3,AP,4K,S_V4)
Engine: 406 Hyd Roller 236/242
Transmission: 700R4 HomeBrew, 2.4K stall
Axle/Gears: 3:73 Posi, 7.5 Soon to break
Re: fuel pressure problem

Sounds like the fuel pump relay is not working.
Will cause long crank time because the pump is being turned on by the oil pressure switch.
Would also get no fuel with key on, engine off.
Jp
Old 09-19-2014, 12:28 PM
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Car: Trans Am gta 5.7 1989
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Transmission: th700r4
Axle/Gears: BG 9 bolt
Re: fuel pressure problem

Oki and how do i test the Fuel pump relay ?
Old 09-29-2014, 02:21 PM
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Car: 1989 Trans Am GTA
Engine: Procharged 350tpi
Transmission: uprated 700R4
Re: fuel pressure problem

check for power at the pump feed wire with a test light or multi meter
should power up for a few seconds when you turn the ignition on

if no power then check for power/earth from ecu at the relay
Old 09-29-2014, 06:13 PM
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After I did my engine swap I had a hard start issue. It was due to the fuel pressure reg. If you can find the thread on here that I started, probably 2 or 3 pages back, a member was kind emough to provide a flow chart from a gm manual to diagnose this issue. Goodluck
Old 09-29-2014, 06:16 PM
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Car: 1987 iroc
Engine: 383 TPIS intake, Dyno Don headers
Transmission: 700R4 w/Pro-built Auto/transgo 2-3
Axle/Gears: 3.27/3.70 borg warner 9 bolt
Re: fuel pressure problem

Here's one. http://chevythunder.com/fuel_system_diagnosis.htm Here is the relay chart. http://chevythunder.com/fuel_pump_diagnosis_chart.htm
Old 09-29-2014, 11:21 PM
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Car: Trans Am gta 5.7 1989
Engine: 350 tpi
Transmission: th700r4
Axle/Gears: BG 9 bolt
Re: fuel pressure problem

Thanks will try that.

When engine is running i have about 40-42 psi pressure and when i turn it off it holds the pressure. But if i then turn the key to ing on the pressure is at 0-5 psi.
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