Thread: Fuel pressure loss?

Results 1 to 5 of 5
  1. #1 Fuel pressure loss? 
    SE Level Member
    Join Date
    Dec 2020
    Location
    Huntsville, Alabama
    Posts
    2
    Thanks (Received)
    0
    Likes (Received)
    0
    Dislikes (Received)
    0
    Chats
    0
    Hi all,

    My first post on grandprixforums! Thank you all for this very helpful site.

    I have a '98 Grand Prix GTP. I noticed that after the car is off for ~8 hours, there's no longer any fuel pressure at the Schrader valve on the fuel rail. I didn't think much of this as the car was still starting fine.

    However, the fuel pump recently went out and I went ahead and replaced both the fuel pump AND the fuel injectors with new OEM (Delphi, Bosch, respectively) components.

    This got me curious - surely it was one of those two that was causing the fuel pressure loss, right?

    But when I tested the Schrader valve again today, it had still lost all fuel pressure after ~8 hours.

    Is this loss normal? Or is there some other component that could be causing this fuel pressure loss over time? The car runs well, no OBD codes, scan tool gives sensible data, and I do not see or smell fuel or observe any loss in fuel tank level over time.

    Thank you!

    -Jen
    Reply With Quote  
     

  2. #2 Re: Fuel pressure loss? 
    GT Level Member mguzzo's Avatar
    Join Date
    Dec 2007
    Location
    Buffalo NY
    Posts
    483
    Thanks (Received)
    8
    Likes (Received)
    27
    Dislikes (Received)
    0
    Chats
    25
    could be the checkvalve in the pump is back-leaking.
    It really doesn't matter, just key-on and wait for the pump to prime for two seconds.
    --
    "Silver Bullet" 98 GTP Coupe: Stock, rust free, and broadsided.
    Old '98 GTP Coupe: VS Cam, 3.0, S2IC, 42.5#, TOGs, N*/LQ4, Corsa. it once ran a 13 flat
    Older '98 GTP Sedan: Pullied, rockered, SSIC, etc. Stock 14.33 @ 96.5 / PB: 13.89 @ 101
    Reply With Quote  
     

  3. #3 Re: Fuel pressure loss? 
    Killa Bee Scottydoggs's Avatar
    Join Date
    Aug 2010
    Location
    new jersey
    Posts
    39,995
    Thanks (Received)
    63
    Likes (Received)
    166
    Dislikes (Received)
    5
    Chats
    243824
    yes normal for the fp to drop over 8 hrs sitting.

    98 Buick Regal GS, F body brakes, Caddy STS wheels, tinted tails L36 bottom end, lightly ported heads, 1.95 roller rockers, headers, gen 5 N* 3.0 pulley, FSIC, 42 lb injectors, a BrandonHall rebuilt trans, DHP tuned and AEM water/Meth injection https://goo.gl/gpV5kW
    Reply With Quote  
     

  4. #4 Re: Fuel pressure loss? 
    Turbo is the way to go. Fivefingerdeathpunch's Avatar
    Join Date
    Sep 2009
    Location
    Rogers, MN
    Posts
    21,030
    Thanks (Received)
    21
    Likes (Received)
    45
    Dislikes (Received)
    0
    Chats
    83662
    It should only hold fuel pressure for maybe 5-10 minutes and not hours.

    This is why when you turn the key to the on position it primes the fuel system for 2 seconds.

    SMGPFC Member #1
    Reply With Quote  
     

  5. #5 Re: Fuel pressure loss? 
    SE Level Member
    Join Date
    Dec 2020
    Location
    Huntsville, Alabama
    Posts
    2
    Thanks (Received)
    0
    Likes (Received)
    0
    Dislikes (Received)
    0
    Chats
    0
    Okay, understood. Thank you very much mguzzo, scottydoggs, and Fivefingerdeathpunch!
    Reply With Quote  
     

Similar Threads

  1. Replies: 19
    Last Post: 10-20-2015, 09:22 PM
  2. Hi pressure low pressure fuel connectors , i lost the springs that go inside. help
    By Hardonyomom in forum 3.8L V6 Supercharged (L67)(L32)
    Replies: 8
    Last Post: 10-20-2014, 09:31 PM
  3. huge exhaust leak resulting in loss of back pressure causing tranny problems?
    By McCoyH in forum 1997-2007 4 speed Automatic (4T65E) (4T65E-HD)
    Replies: 18
    Last Post: 05-05-2012, 09:35 AM
  4. fuel loss
    By janiuay123 in forum 3.8L V6 Naturally Aspirated (L36)(L26)
    Replies: 6
    Last Post: 03-20-2008, 12:09 PM
Tags for this Thread

View Tag Cloud

Bookmarks
Bookmarks
Posting Permissions
  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •