fuel pressure question
Thread Starter
Joined: May 2005
Posts: 728
Likes: 1
From: Toronto, Ohio
Car: 1991 Trans Am GTA
Engine: 355
Transmission: 4L60
Axle/Gears: 4th gen 10 bolt 3.42 posi
fuel pressure question
How long should presssure hold in the system? Mine holds for less than 45 seconds and i have smelled fuel a few times after some WOT bursts, but cant find any leaks.
Senior Member
Joined: Nov 2011
Posts: 507
Likes: 1
From: Charlotte, NC
Car: 1988 IROC-Z Camaro, 1981 Trans Am
Engine: 350 TPI, 301 N/A
Transmission: 700r4, 350thm
Re: fuel pressure question
You talking about how long it should hold after priming the pump or shutting it off right? 30 seconds, so your ok there.
Wheres the fuel smell come from?
Wheres the fuel smell come from?
Joined: Apr 2005
Posts: 7,736
Likes: 14
From: Not in Kansas anymore
Car: 82 Z28
Engine: 383 SP EFI/ 4150 TB
Transmission: T400
Axle/Gears: QP 9" 3.73
Re: fuel pressure question

30 minutes more like it
More important question is what pressure does it drop to?
If pressure drops low straight away ( less than 5 min ) either fuel reg or one way valve in tank is faulty
https://www.thirdgen.org/forums/tpi/...rops-when.html
https://www.thirdgen.org/forums/tpi/...ero-right.html
Last edited by vetteoz; May 20, 2012 at 10:20 PM.
Thread Starter
Joined: May 2005
Posts: 728
Likes: 1
From: Toronto, Ohio
Car: 1991 Trans Am GTA
Engine: 355
Transmission: 4L60
Axle/Gears: 4th gen 10 bolt 3.42 posi
Re: fuel pressure question

30 minutes more like it
More important question is what pressure does it drop to?
If pressure drops low straight away ( less than 5 min ) either fuel reg or one way valve in tank is faulty
https://www.thirdgen.org/forums/tpi/...rops-when.html
https://www.thirdgen.org/forums/tpi/...ero-right.html
The fuel smell would seem to be coming from under the hood and only happened when I got on it hard and then the smell would fill the car for a minute. It only happened a few times and I haven't noticed it in a while, but my fuel economy seems to be really bad ever since then. I checked my injectors for ohms and leakage and I don't see anything leaking anywhere. BUT, when I took my fuel pressure gauge off yesterday and turned on the key, the schrader valve was stuck open and spraying fuel everywhere. I took a screwdriver and pressed it in and released it and it sealed up, so I'm wondering if it was leaking.
Senior Member
Joined: Nov 2011
Posts: 507
Likes: 1
From: Charlotte, NC
Car: 1988 IROC-Z Camaro, 1981 Trans Am
Engine: 350 TPI, 301 N/A
Transmission: 700r4, 350thm
Re: fuel pressure question
Really? I was told it should hold for 30seconds after priming or shutting the car off. Idk where they got that from. Glad you caught it though vette lol
Thread Starter
Joined: May 2005
Posts: 728
Likes: 1
From: Toronto, Ohio
Car: 1991 Trans Am GTA
Engine: 355
Transmission: 4L60
Axle/Gears: 4th gen 10 bolt 3.42 posi
Re: fuel pressure question
Ok, did some playin around and here is what i found out. Clamped the return shut and when i turn on the key it shoots up to 65 psi and as soon as the pump kicks off it quickly drops. Leaky injector? I see no leaks externally.
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