Fuel delivery problems..

Maverick26 · Feb 19, 2010

I had a guy come to my shop with a nice old gen CJ5. He is a friend of mine and I was going to help him get his new motor running. He has a 4.3L V6 and an fuel cell so all the stock stuff is gone. I went an got him a napa electric fuel pump that is for the 2001 motor. I have about 2 gals of gas in the tank that is fresh. In line fuel filter was installed like they say to. The pump has an arrow on it that is pointing to the motor. Seems like all the obviose is good but I stll cant get fuel to the motor. What is wrong?

zukkev · Feb 19, 2010

What's the fuel psi at??? Where's the pump mounted? An '01 4.3L should have had an in tank pump, which doesn't have an arrow... but the minimum fuel psi spec is 56 psi on this era...if it's not at least 56, the motor won't start.

crash2 · Feb 19, 2010

zukkev said:
What's the fuel psi at??? Where's the pump mounted? An '01 4.3L should have had an in tank pump, which doesn't have an arrow... but the minimum fuel psi spec is 56 psi on this era...if it's not at least 56, the motor won't start.

Actually its 40 psi kev for it to fire off. The poppet valves on the injectors won't blow below 40 :awesomework:

Maverick26 · Feb 19, 2010

So the pump is a aftermarket napa frame mount pump. It was late last night so I didnt get to test the pressure. The motor ran good for 5-6 seconds untill the starting fluid ran out so I know it runs its just not getting fuel. Ill check for at least 56psi. I have a feeling the pump may be bad cause I filled the filter up with fuel right before the pump, I turn the pump on and it does not suck any fuel out of the filter... nothing. The pump runs, I can hear/feel it running. Not sure what is up.

Boosted · Feb 19, 2010

New pump with the vanes broke off the shaft? What ever happened to quality control? I would take that thing back to NAPA and get a new one.

Maverick26 · Feb 19, 2010

Boosted said:
New pump with the vanes broke off the shaft? What ever happened to quality control? I would take that thing back to NAPA and get a new one.

Im not sure what this means Bill? I think the pump is bad too.

Boosted · Feb 19, 2010

Not sure what kind of pump it is, but if you hear it running but nothing is being pumped thru, then it sounds like "the little propeller thingy attached to the little motor that is spinning that makes the pump, pump" is broken. :;

Go take that thing back and get another one. :awesomework:

Maverick26 · Feb 19, 2010

Ok thanks bro, Thats the plan this afternoon. Ill get back to you all if it works or not. Thanks. :awesomework:

TreeClimber · Feb 19, 2010

Before you replace that pump, make sure that the fuel line from the pump to the motor isn't blocked, clogged, pinched, etc... If the pump is trying to pump to a blocked line, you'll have problems. Also, my GM motor transplant required a return line to the tank. In theory, if tyou don't have a return line, then the air that's trapped in the line may have nowhere to go.

Not saying this is your problem,.. just another facet to consider.

Boosted · Feb 19, 2010

TreeClimber said:
Before you replace that pump, make sure that the fuel line from the pump to the motor isn't blocked, clogged, pinched, etc... If the pump is trying to pump to a blocked line, you'll have problems. Also, my GM motor transplant required a return line to the tank. In theory, if tyou don't have a return line, then the air that's trapped in the line may have nowhere to go.

Not saying this is your problem,.. just another facet to consider.

Good point. I was thinking the same thing until I read that he ran fuel to the filter and inlet of the pump, turned it on and nothing came out.

TreeClimber · Feb 19, 2010

Boosted said:
Good point. I was thinking the same thing until I read that he ran fuel to the filter and inlet of the pump, turned it on and nothing came out.

I didn't read it the same as you did. What I read is that he ran fuel to the filter and inlet of the pump, turned it on, and it didn't suck anything out of the filter.

Which means that he may not have disconnected the pump from the line to the motor.

Of course, my reading comprehension isn't that good.

Maverick26 · Feb 19, 2010

Hey guys im still struggling with this. I called napa and looked up the part number. I think I may have the wrong pump. They insist that the pump I have is the one I need but I have my doubts. This is it and its only rated for 9-22psi.
http://www.napaonline.com/Search/Detail.aspx?R=NFPP5001_0249686618

Please if anyone has a part number they have from napa that will work for a 2001 4.3L V6 vortec TBI let me know.

I have a hard line that goes from the motor to the pump then rubber from the pump to the filter (about 4" apart) then rubber from the back of the filter to the tank. The return line is rubber also. I took the air hose and blew them out to be sure that there was nothing in the line. Then filled up the filter with fuel and turned the pump on and it didnt suck any fuel.

TreeClimber · Feb 19, 2010

Unhook the output line, and test the pump. Report results.

Make sure to have rags handy.
Make sure to have fire extinquisher handy.
Make sure to not catch yourself, or the garage on fire.

Maverick26 · Feb 19, 2010

Do you guys run a regulator to boost the pressure up about the 40-60psi range? I thought that these pumps where ment for EFI motors. What does my fuel pressure need to be cause my pump is only putting out about 15psi.

zukkev · Feb 19, 2010

'01 Vortec 4.3 is not TBI, if you're telling the parts house it's TBI, then that may be why you got the wrong pump...should be SFI 4.3L...
I have seen several bad pumps over the years run up to 52 psi, and the vehicle not start....replace pump; gets to 60 psi and starts! (Not doubting you're GM expertise Mike :redneck:, just sayin' what I've experienced!!!:awesomework

...

zukkev · Feb 19, 2010

Maverick26 said:
Do you guys run a regulator to boost the pressure up about the 40-60psi range? I thought that these pumps where ment for EFI motors. What does my fuel pressure need to be cause my pump is only putting out about 15psi.

Wrong pump...check for an inline pump for a SFI 4.3L....IIRC an early BB EFI ford frame rail pump would net you the pressure needed, but I'd research this some before ordering!:awesomework: The fuel pressure regulator inside the upper plenum take care of regulation....no external regulator/booster...:eeek:

Maverick26 · Feb 19, 2010

So 60psi needs to be the pressure at the injectors right? So how do I get that with a 9-22psi pump? I got the pump by asking napa for an electric fuel pump for a 2001 blazer with the 4.3L. Ill let them know its a SFI.

Maverick26 · Feb 19, 2010

Hmmm.... :eeek: A Big block ford frame rail pump will do? Ok. Ill look at the numbers. I figured there was a regulator in the plenum so I didnt run one.

Maverick26 · Feb 19, 2010

Early? Like 1997 with the 460?

crash2 · Feb 19, 2010

zukkev said:
'01 Vortec 4.3 is not TBI, if you're telling the parts house it's TBI, then that may be why you got the wrong pump...should be SFI 4.3L...
I have seen several bad pumps over the years run up to 52 psi, and the vehicle not start....replace pump; gets to 60 psi and starts! (Not doubting you're GM expertise Mike :redneck:, just sayin' what I've experienced!!!:awesomework...

I have ran across the same issue Kev---and always found it was a volumn issue