Results 1 to 13 of 13

Fuel pressure test failure, where to start?

This is a discussion on Fuel pressure test failure, where to start? within the External Engine forums, part of the LSx Technical Help Section category; Takes several cranks to start the car so I did a fuel pressure test and this is what it does ...

  1. #1
    Junior Member LS1 oldtimer's Avatar
    Join Date
    Sep 2010
    Location
    Texas
    Age
    52
    Posts
    41

    blue
    2001

    Fuel pressure test failure, where to start?

    Takes several cranks to start the car so I did a fuel pressure test and this is what it does is:

    Hooked the guage up without starting and there was no pressure. Turned the key on (without starting) and pressure built up to 59 then something clicks under the hood and the pressure falls immediately to near zero. While the car is running the pressure stays at 59, as soon as the key is turned off the pressure falls to zero. Another thing I noticed was when I unscrewed the gauge I could hear a little pressure escaping from the test port. Where should I start?

  2. #2
    Super Moderator
    pajeff02's Avatar
    Join Date
    Feb 2009
    Location
    Mansfield, PA
    Posts
    21,576

    Black & Blue
    '02 WS.6 / '07 Suburban

    Not mess with the fuel system. Sounds like it is working fine to me.

  3. #3
    None Shall Pass Knight's Avatar
    Join Date
    Jan 2010
    Location
    East of Cleveland, Ohio
    Posts
    3,828

    Black
    99 WS.6 - Modified

    Agree. With the description given, I don't see anything wrong.

  4. #4
    Former Mopar Man 2002ssslp's Avatar
    Join Date
    Jun 2011
    Location
    Branchville, NJ
    Posts
    3,111

    Silver & Blue
    02 Camaro SS, 04 GTO

    You may have some clogged injectors, plugs may need to be changed, How is your air filter, coils working ok. I would poke around and see what you can find. Pressure is fine.
    My ride is a 2002 Camaro SS SLP #3296 with 30k, LTH, 3" Y, CME, Frost tune, K&N, ported TB, Blackwing lid, Bellows, MSD, Denso Iridium, and 85mm MAF, Bilsteins, Eibach springs, SLP strut brace, Adj. Panhard, TA Girdle, UMI, Pro 5.0, Nitto NT555
    My wife has a 2004 GTO with the rare SAP, 18" wheels, K&N Cold Air System, MSD, Ported TB, Frost tune, Denso Iridium, Flowmaster cat-back, 3200 Yank, 75k

  5. #5
    Junior Member LS1 oldtimer's Avatar
    Join Date
    Sep 2010
    Location
    Texas
    Age
    52
    Posts
    41

    blue
    2001

    Thanks for the replies. I thought it was supposed to hold the pressure. The air filter is new and the car runs perfect once it starts so I didn't think it would be the plugs.

  6. #6
    Member 383ls6's Avatar
    Join Date
    Nov 2009
    Location
    dallas,texas
    Posts
    158

    red
    2002 z/28

    it should hold pressure for a couple of minutes. if it falls to zero immediately then you need to replace the fuel pump module.
    Last edited by 383ls6; 03-24-2013 at 04:22 PM.

  7. #7
    Senior Member redbird555's Avatar
    Join Date
    Mar 2009
    Location
    pompano beach florida
    Age
    27
    Posts
    1,008
    2002 Camaro Z/28 Pewter

    Quote Originally Posted by 383ls6 View Post
    it should hold pressure for a couple of minutes. if it falls to zero immediately then you need to replace the fuel pump module.
    This^^^ You should see it hold pressure for a few minutes at least. Sounds like the pressure regulator has gone bad, so you you either need to disassemble the module and replace it or get a new module. Try this test to confirm, next time you start the car turn the key on and wait a few seconds then turn the key to start it. This will prime the pump first and I bet it will kick over.

  8. #8
    Spaz is My Mentor SMWS6TA's Avatar
    Join Date
    Feb 2009
    Location
    Ugy Lower Corner of AL
    Posts
    10,511

    Navy Blue Metallic
    98 T/A w/a little mods...

    Most likely the drop in fuel pressure is a result of the pick up tube having a crack.


    Does it do this at certin levels of fullness with the tank? Meaning does it do this when you're half full, 3/4, 1/4? That is another way to check.

  9. #9
    None Shall Pass Knight's Avatar
    Join Date
    Jan 2010
    Location
    East of Cleveland, Ohio
    Posts
    3,828

    Black
    99 WS.6 - Modified

    Mine will drop pretty fast. I don't know if I'd call it immediate, but definately not a few minutes. Never had an issue.

    OP- if you don't start the car, but turn the key on, and let the pressure build and fall, then turn the key off and back on again, does it build pressure again?

  10. #10
    Super Moderator
    pajeff02's Avatar
    Join Date
    Feb 2009
    Location
    Mansfield, PA
    Posts
    21,576

    Black & Blue
    '02 WS.6 / '07 Suburban

    Same. If I turn on my ignition without starting the car, it will jump to 58 or 59 psi. After a few seconds, it'll drop into the 40's. Haven't really paid attention to what it does after that.

  11. #11
    Junior Member LS1 oldtimer's Avatar
    Join Date
    Sep 2010
    Location
    Texas
    Age
    52
    Posts
    41

    blue
    2001

    Turning the key and waiting a few seconds doesn't seem to help it but cycling the key on and off a couple times does seem to help.

  12. #12
    Veteran 0rion's Avatar
    Join Date
    Aug 2005
    Location
    ohio
    Posts
    22,520

    98 Formula
    06 duramax

    sounds like a bad fuel pressure regulator to me.....it could possibly be as simple as the according hose in the tank that supplies the pump being cracked but normally that pressure wouldn't fall that fast I don't believe. I would open it up and inspect that hose first and then look at the regulator if that hose isn't cracked. GM parts direct lists a fuel pressure regulator ($3.20) but I'm not sure I've ever known anyone that's replaced just the regulator so I'm not sure how serviceable that part is. If you do find that it's the hose make sure you use submersible hose and not regular fuel line. You'll want to go to NAPA and ask for SAE 30R10 hose. Another good idea would be to replace your pump while you're in there with a racetronix pump since you'll be right there anyhow.

  13. #13
    Junior Member LS1 oldtimer's Avatar
    Join Date
    Sep 2010
    Location
    Texas
    Age
    52
    Posts
    41

    blue
    2001

    Thanks to everyone and yes I agree if I'm going to have to go in there I might as well do the whole module.


LinkBacks (?)

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Fuel Pressure Test - Assistance Requested
    By pajeff02 in forum General Help
    Replies: 7
    Last Post: 05-14-2014, 03:24 AM
  2. Question: Scanner link Failure engine cranks but does not start
    By USengines in forum General Help
    Replies: 20
    Last Post: 05-04-2013, 05:40 AM
  3. How do you test a fuel pressure regulator?
    By cullywoo in forum General Help
    Replies: 0
    Last Post: 09-09-2012, 01:09 PM
  4. Long start, fuel pressure reg?
    By Chicago TDP in forum General Help
    Replies: 4
    Last Post: 09-21-2007, 05:58 AM
  5. Replies: 5
    Last Post: 04-04-2007, 12:06 AM

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
  •