fuel pressure drops off after cycling ignition
#1
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fuel pressure drops off after cycling ignition
Engine off, my fuel pressure goes up to 45psi when I cycle the ignition. The pressure then drops off from 45 to 22psi after about 10-15 seconds. Next I tested the injectors they were all 16.9-17.1 ohms. I ran an injector balance test and all but one injector dropped down to 16psi the other was 14psi. Is this the cause for the fuel pressure drop off, or is it something else? If the car is sitting for a little while i usually have to give it a little gas to get it started, but if its not sitting to long it starts fine.
Last edited by louflemm; 10-31-2009 at 12:05 AM.
#2
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Car: 82 Z28
Engine: 383 SP EFI/ 4150 TB
Transmission: T400
Axle/Gears: QP 9" 3.73
Re: fuel pressure drops off after cycling ignition
Check valve in tank or regulator leaking down for starters.
There is a test proceedure in the FSM for determining whether supply or return side is leaking.
There is a test proceedure in the FSM for determining whether supply or return side is leaking.
#3
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Car: 82 Z28
Engine: 383 SP EFI/ 4150 TB
Transmission: T400
Axle/Gears: QP 9" 3.73
Re: fuel pressure drops off after cycling ignition
It is injected , you can't " give it gas" .There is no squirter like on a carb.
If it starts easier with the throttle open then that is a indication the engine has too much fuel ( injectors leaking down? ) .By opening the throttle you are stopping the injectors firing and adding more air to clear the flooded condition
If it starts easier with the throttle open then that is a indication the engine has too much fuel ( injectors leaking down? ) .By opening the throttle you are stopping the injectors firing and adding more air to clear the flooded condition
#4
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Car: camaro
Engine: 5.7 tuned port injection
Transmission: 700r4
Axle/Gears: 327 posi
Re: fuel pressure drops off after cycling ignition
yeap mine does the same thing also ! i assumed it was the injectors leaking down ...
#5
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Car: 86' IROC-Z....and 5 other 3rdgens
Engine: 383 hsr
Transmission: built 700r4
Axle/Gears: stock 3.23, 10bolt
Re: fuel pressure drops off after cycling ignition
yeah an injector leak down could be it, but id go with the fuel pressure regulator first. that sounds more like it. and its a cheaper and quicker fix AND easier to tell if its bad right from the git go.
#6
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Car: 86' IROC-Z....and 5 other 3rdgens
Engine: 383 hsr
Transmission: built 700r4
Axle/Gears: stock 3.23, 10bolt
Re: fuel pressure drops off after cycling ignition
haha sorry, i take back what i said about it being "cheaper and easier to swap out" IF its a tpi. is it a tpi?
#7
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Car: 85' Trans Am !best car ever!
Engine: 305tpi 215hp LB9 two bolt,
Transmission: th-700r4
Axle/Gears: stock (3.27)
Re: fuel pressure drops off after cycling ignition
tpi is pretty much is the most efficient in my opinion, provided the fact im talking about a accel plenum port polished. ANYWAYS i was going to say, my pressure hits about 42psi then drops to zero. BUt the injectors are fine and run solid. cause? leaking neoprene hose with self adjuster clamps. I thought self adjuster clamps was weird, but it was some of the advice i seen on this board. im going to leave it untill i rebuild the rear diff when it blows up. knock on wood
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