2001 Tahoe Fuel pump or the fuel pressure regulator?

eightshot627

Original poster
Member
Aug 8, 2012
79
2001 Chevy Tahoe, 5.3L, Auto, 4x4, 155K, I’ve owned her since 135K
She has been slow to start. She cranks just fine but takes awhile to start and then stumbles a little and then runs fine. Once she does start then you can shut her down and restart her at will. I changed the plugs and wires (ACs) and put on a new fuel filter no change. It must be fuel now but is it the pump or the fuel pressure regulator?
Fuel pressure:
After sitting all night put the gauge on and no gas came out of the connector 0psi.
At key on the pressure goes to 32 psi. Key on again pressure goes to 35 psi. Key on again pressure goes to 37 psi.
Start the truck the gage goes all over 25-50 once running she settles out at 50 psi. Pull the vacuum line off the fuel pressure regulator and the pressure goes up to 56 then back down to 50 psi after it is replaced. No fuel in the fuel pressure regulator vacuum line.
I shut her down and fuel pressure was at 50 psi. After 30 minutes still 50 psi. After 1 hour 49 psi. After 5 hours 45 psi.
Fuel pump or the fuel pressure regulator?

Thanks,
Walt
 

BlazingTrails

Member
Apr 27, 2014
19,409
It really sounds to me like the fuel pump is getting weak. Also and i may be wrong as i dont have all data in front of me, but there should be a foot valve in the pump assembly that's keeps the fuel from leaking back over night. Have you tried cycling the pump 3-4 times before starting it cold? Also I have to ask forgive me.. Have you changed the filter?
 

eightshot627

Original poster
Member
Aug 8, 2012
79
BlazingTrails said:
It really sounds to me like the fuel pump is getting weak. Also and i may be wrong as i dont have all data in front of me, but there should be a foot valve in the pump assembly that's keeps the fuel from leaking back over night. Have you tried cycling the pump 3-4 times before starting it cold? Also I have to ask forgive me.. Have you changed the filter?
I'm leaning toword the pump too but I wanted a second opinion. OP has the new filter and cycling the key with 32, 35, and 37 psi before start. After cycling it doesn't change starting much as it is still low pressure.

Thanks,
Walt
 

eightshot627

Original poster
Member
Aug 8, 2012
79
[SIZE=medium]I ordered a Delphi fuel pump and installed it through the top. Now she has 57 psi at key on and 51 psi running. Starts like a champ! [/SIZE]

For those going in from the top look at the floor cuts:

http://www.gmtruckclub.com/forum/threads/another-fuel-pump-access-repair.76394/#axzz1yQKpesK5

[SIZE=medium]I would make my cuts just to the driver side of the spot welds closer to the un-used stud. Then make the cuts just like shown. Those spot welds on mine didn’t just “pop” they took some work. An oscillating multi tool with a half moon metal blade worked great for the cuts. My retaining ring was really rusted and need to be replaced but other than another trip to the parts store it was easy. It beat the heck out of lying in my gravel driveway. I have replaced other in tank pumps before by dropping the tank, twice on my 96 Chevy P/U and once on a 96 Tahoe, this was a piece of cake.[/SIZE]

[SIZE=medium]Good Luck![/SIZE]
[SIZE=medium]Walt[/SIZE]
 

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