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TBI help...can't get fuel press. LOW ENOUGH...

Discussion in 'The Garage' started by fortcollinsram, Jun 26, 2003.

  1. fortcollinsram

    fortcollinsram 1/2 ton status

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    TBI help...can\'t get fuel press. LOW ENOUGH...

    After installing my 454 and taking for a ride, it was blatantly obvious that my in-tank pump that had 150,000 miles on it was not up to the task of providing enough fuel pressure to fuel my 454...it was only provinding 9psi at idle and 7 psi when I stomped on it...So I dropped the tank, installed a NEW AC Delco EP386 pump and strainer, botl the tank back in, and it starts right up...but now I can't get it below 15psi of fuel pressure /forums/images/graemlins/eek.gifI have the Jet adjustable fuel pressure regulator and it is cranked all the way OUT, so that it should be providing as little fuel pressure as possible...it is still at 15 and drops to about 14.5 when I romp on it....

    Any ideas?

    Chris
     
  2. dyeager535

    dyeager535 1 ton status Premium Member

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    Re: TBI help...can\'t get fuel press. LOW ENOUGH...

    Might want to have that fuel pressure regulator checked, my dad bought one and it failed. Stupid POS had him troubleshooting for quite awhile.
     
  3. fortcollinsram

    fortcollinsram 1/2 ton status

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    Re: TBI help...can\'t get fuel press. LOW ENOUGH...

    how does it fail? It is simple as a dirt. The regulator does adjust the spring seat both tighter than oringinal spring and also lighter...I am going to throw the stock regulator on tomorrow and see if that brings the pressure down at all...

    Chris
     
  4. HarryH3

    HarryH3 1 ton status Author

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    Re: TBI help...can\'t get fuel press. LOW ENOUGH...

    Are you sure that the pump you bought is for a TBI application? I'd think that one from a multi-port setup would be kickin' out way more pressure than a TBI regulator could deal with.
     
  5. dyeager535

    dyeager535 1 ton status Premium Member

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    Re: TBI help...can\'t get fuel press. LOW ENOUGH...

    [ QUOTE ]
    how does it fail? It is simple as a dirt.

    [/ QUOTE ]

    Dunno, but after driving on the freeway for some time, and finally slowing down, the vehicle would start bucking, and finally die. Check the carb, no fuel. Figured heat soak (had just swapped in a BBC with electric fuel pump) so mde sure everything was out of the way and properly shielded, and problem didn't go away.

    Finally removed the regulator completely (after screwing with it's settings) and the problem never came back. When it was screwing up, the failure was 100% repeatable. Don't know how, nor why, but it *was* the cause.
     
  6. fortcollinsram

    fortcollinsram 1/2 ton status

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    Re: TBI help...can\'t get fuel press. LOW ENOUGH...

    Harry,

    The pump is the AC Delco replacement pump for TBI applications, I checked and double-checked the number (ep386) at Napa, GM, and several other sources...All said it was the correct pump...unless it was boxed incorrectly... /forums/images/graemlins/eek.gif I will do a check tomorrw and block of the feed line and check the ctual pressure that the pump is cranking out...

    Chris
     
  7. Xtreme Off-Road

    Xtreme Off-Road Registered Member

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    Re: TBI help...can\'t get fuel press. LOW ENOUGH...

    Check for a kink or blockage in the return line.
     
  8. mosesburb

    mosesburb For Rent Premium Member GMOTM Winner

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    Re: TBI help...can\'t get fuel press. LOW ENOUGH...

    SOME people definitely won't agree with me on this one, but I say leave it alone. I run adjustable regulators on all of my TBI vehicles and set them all at 16-18 PSI for max performance (I have gone as high as 19-20, but there wasn't any gain over 18psi). Some will say this is bad, but I have been running it this way for many years (over 100K miles between the different vehicles) and have had absolutely no problems with overfueling, fuel pump longevity, injectors, or any other fuel system components. SOME will claim I am BSing on this, but I have actually had an increase in fuel economy as well. On my 4.3L I went from 18mpg highway to 19mpg highway, and on a 350 I went from 13-14, to 15 on the highway. This increase in fuel pressure also allows you to put more timing in the motor. The beautiful thing about TBI (as compared to Vortec) is the computer doesn't know where zero is when it comes to timing. This being the case you can just turn the dist to add timing without disconnecting the tan/white (EST) wire. Just grab the dist and turn (pretend it is an old HEI) take it for a test drive and if it doesn't ping, add some more. Keep adding until it pings under load, then retard it a bit (no timing lights allowed here). It works great and chances are you will find some power you didn't know was available. Have fun!
     

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