Tech / General Engine Is your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
Sponsored by:
Sponsored by: CARiD

fuel pressure question

Thread Tools
 
Search this Thread
 
Old May 20, 2012 | 05:14 PM
  #1  
budfreak1's Avatar
Thread Starter
Senior Member
20 Year Member
iTrader: (7)
 
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.
Reply
Old May 20, 2012 | 08:42 PM
  #2  
Black88Z's Avatar
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?
Reply
Old May 20, 2012 | 10:13 PM
  #3  
vetteoz's Avatar
Supreme Member
20 Year Member
iTrader: (13)
 
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

Originally Posted by Black88Z
30 seconds, so your ok there.

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.
Reply
Old May 21, 2012 | 08:13 AM
  #4  
budfreak1's Avatar
Thread Starter
Senior Member
20 Year Member
iTrader: (7)
 
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

Originally Posted by vetteoz

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
This is what I thought. It drops down to about 8-10 lbs. within 30-45 seconds and then slowly drops to zero over the next minute or two. It holds rock steady at 32 psi while idling with the vacuum line hooked up to it.
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.
Reply
Old May 21, 2012 | 09:11 AM
  #5  
Black88Z's Avatar
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
Reply
Old May 26, 2012 | 04:08 PM
  #6  
budfreak1's Avatar
Thread Starter
Senior Member
20 Year Member
iTrader: (7)
 
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.
Reply
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
92camaroJoe
TBI
32
Jul 29, 2023 07:57 PM
MustangBeater20
TBI
11
Oct 29, 2022 09:20 PM
R3500
Engine/Drivetrain/Suspension Wanted
1
Aug 17, 2015 12:16 PM
92camaroJoe
Tech / General Engine
6
Aug 13, 2015 06:07 AM
Kaweh
TBI
3
Aug 9, 2015 02:54 PM




All times are GMT -5. The time now is 05:07 PM.