fuel pressure when engine off?
fuel pressure when engine off? Should the fuel pressure stay at what engine runs at when engine is switched off, eg engine runs 58psi should it hold this psi with pump off or is it normal to slowly drop back to near 0?
TECH Regular
Joined: Feb 2003
Posts: 451
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From: Spring Hill, TN
It will drop somewhat, but some pressure will remain. I haven't measured it to know what it drops to.
This is why service procedures for the fuel system have you release fuel pressure before servicing. The easiest way is to pull the fuel pump fuse while idling until the car stalls, then work on the fuel system.
This is why service procedures for the fuel system have you release fuel pressure before servicing. The easiest way is to pull the fuel pump fuse while idling until the car stalls, then work on the fuel system.
TECH Regular
Joined: Feb 2003
Posts: 451
Likes: 0
From: Spring Hill, TN
Well, I haven't really given it any thought before. I can't imagine that the pressure will stay indefinitely. My guess is that it would push back through the inactive fuel pump. As far as I know the only concern is whether it maintains proper pressure while running. Were you concerned you have a leak somewhere? I wouldn't assume that simply because the pressure drops overnight.
Originally Posted by GTS346
yep am aware it holds pressure, when engine shuts off it drops to around 52psi straight away, then after 2 minutes its near 30psi, by the next morning its next to nothing.
What pump? A good stock pump will hold pressure over night. A Walbro 340M will loose some but should take quite a while. Loosing pressure just means the check valve in the pump is not working and will cause long cranking before starting has to build pressure back up first. Should not have anything to do with the running of the car.
Nate
Nate
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Verdad Gallardo Ok I found the problem, it is not the fuel pump it was the Aeromotive 13109 by pass regulator.
This is common with these regs, was reading thru there instructions and it states "the fpr may not hold significant pressure after the fuel pump stops running" "As there is slight air leakage thru adjustment screw threads, does not affect operating performance".
Just thought it might help someone out if they come across this at a later date when searching with same issues.
This is common with these regs, was reading thru there instructions and it states "the fpr may not hold significant pressure after the fuel pump stops running" "As there is slight air leakage thru adjustment screw threads, does not affect operating performance".
Just thought it might help someone out if they come across this at a later date when searching with same issues.
Originally Posted by GTS346
Ok I found the problem, it is not the fuel pump it was the Aeromotive 13109 by pass regulator.
This is common with these regs, was reading thru there instructions and it states "the fpr may not hold significant pressure after the fuel pump stops running" "As there is slight air leakage thru adjustment screw threads, does not affect operating performance".
Just thought it might help someone out if they come across this at a later date when searching with same issues.
This is common with these regs, was reading thru there instructions and it states "the fpr may not hold significant pressure after the fuel pump stops running" "As there is slight air leakage thru adjustment screw threads, does not affect operating performance".
Just thought it might help someone out if they come across this at a later date when searching with same issues.
thats good to know, i just got one of those reguators.
