Fuel pressure

DOZER1401

MEMBER
2004 CHEVROLET
V8
4WD
AUTOMATIC
120,000 MILES

I have a 2004 Dura Max 6.5 deisel with the Allison trans. I can not get it to hold its fuel prime, Ive changed out the fuel filter with new O rings on the filter, and used the onborad manual fuel prime pump, but still cant get it to hold its prime, once its started, it only runs a few minutes and its back to primeing again. Any ideas?

6 Replies

HMAC300

MECHANIC
48,601 POSTS

Hopefully you filled the fuel filter before you installed it. You aer supposed to pump the hand pump 30 times then let it sit for a couple of minutes. Then Pump 30 more times and let sit. See if truck will start and let idle for 10 minutes it will take that long for the air to work out of the system. If it won't idle that long then you have air leaking in the system or a vacuum leak and should be checked by a pro.

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Saturday, July 10th, 2010 AT 7:03 PM

JUSTJIM20B

MEMBER
1 POST
1995 CHEVROLET
V8
4WD
MANUAL
148,000 MILES

Replaced in tank fuel pump twice. Parts from napa both pump have only 8psi. Pump spec are 12-15psi. Checked ground, volted, replaced relay, pressure regulator.&Fuel lines. Also ran fuel pump out tank with out filter 8-9psi. Changed pressure guage 3 times to varify. Truck has very little power. Will the lack of pressure affected the power of the truck? PS TBI Help upset

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Tuesday, August 20th, 2019 AT 7:22 PM (Merged)

RASMATAZ

MECHANIC
75,992 POSTS

TBI system-the fuel pressure specification should be 9-13psi

These had what was called a "pulse dampener" on top of the fuel pump. It is a black plastic piece a few inches long between the pump and the tank unit that was supposed to create a steady fuel flow. They go bad internally and by-pass pressure. You should install your new pump with the piece of fuel injection hose supplied with the pump instead of the pulse dampener

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Tuesday, August 20th, 2019 AT 7:22 PM (Merged)

JOSHUAESP

MEMBER
1 POST

Dropped the tank and did what you said. Runs perfect. Thanks so much I was going nuts

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Tuesday, August 20th, 2019 AT 7:22 PM (Merged)

PILOTMOSS

MEMBER
1 POST
1988 CHEVROLET
V8
2WD
AUTOMATIC
37,000 MILES

1988 28 foot Bounder Motor Home, 454 carb. Engine, electric fuel pump in rear gas tank, regulator near tank.
What fuel pressure would be a good setting?
The original regulator was a Holly 12-804 (1 to 4 psi) or a 12-803 (4.5 to 9 psi) adjustable regulator, not sure which one (because last number unreadable).

Thanks, Bob

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