Results 1 to 3 of 3

Thread: fuel pump key on prime

  1. #1
    New Member
    Join Date
    Mar 2024
    Posts
    3

    Default fuel pump key on prime

    The fuel pump key on prime does not work when hot on my 2008 6L Gen4 VE fitted with a 500kW modified supercharged LSA engine retaining the standard E38 ECU. It is fitted with an in tank Walbro 535 lph pump with a modified tank cover retaining all the existing internal tank components to suck fuel from the opposite side of the tank into the surge tank and keep the fuel level sensors working. The in tank fuel pressure regulator and non-return check valve had to be removed to make the pump fit. A new 10mm fuel line runs via a large fuel filter up front through the fuel rails to an AEM fuel pressure regulater returning the dumped fuel via the original fuel supply line back to the tank. The fuel pump key on prime works fine when cold and it starts perfectly when I wait for the fuel pump to complete its current reset 8 second prime time.

    I do not want to fit an in line non-return check valve because the 535 lph pump is already running at its limit to maintain 400 kpa fuel pressure at full power and probably won't deliver enough fuel/pressure with any additional restrictions in the fuel line.

    Can anyone advise me how to make the fuel pump key on prime work at all engine temperatures assuming this is the trigger/culprit?

  2. #2
    Lifetime Member
    Join Date
    Jul 2003
    Posts
    1,907

    Default

    It does work. The issue comes from that if the ECM sets the flag that the engine is primed it will not power up the fuel pump until the ECM either shuts off and clears that ram flag or sees an rpm signal.
    "All that is needed for the triumph of evil is that good men do nothing..."

  3. #3
    Lifetime Member
    Join Date
    Mar 2006
    Posts
    610

    Default

    What is fuel pressure when engine is warm and your not getting the fuel prime?

Similar Threads

  1. Fuel Pump Prime Time
    By chevyunderpressure in forum Gen III V8 Specific
    Replies: 2
    Last Post: August 21st, 2017, 01:24 PM
  2. Initial fuel prime question
    By Rich Z in forum Gen III V8 Specific
    Replies: 39
    Last Post: May 12th, 2013, 06:22 PM
  3. E40 randomly wont prime fuel pump...
    By BLK02WS6 in forum Gen IV V8 Specific
    Replies: 7
    Last Post: June 20th, 2012, 04:45 AM
  4. Replies: 15
    Last Post: May 6th, 2012, 02:20 PM
  5. fuel pump prime - increase time?
    By 350SS in forum General (Petrol, Gas, Ethanol)
    Replies: 12
    Last Post: April 8th, 2007, 08:06 AM

Posting Permissions

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