XJ is sputtering/stalling

So my 95 XJ is sputtering/stalling. 4.0L with a manual. It has a home made fuel cell that uses the factory pump and wiring. New Fuel filter installed facing the correct way.

The XJ runs fine for a few minutes then starts to act up. If you turn the key off, wait a minute, the problem goes away for a few minutes again. Comes back faster if you try to hit a hill or something hard. It seems like the idle goes up and down in a cyclic manner and you can hear the fuel pump making noise in a cyclic manner...noise up...noise down...eeee...oooo...etc. I had a spare fuel pump and I swapped that in and no changed BUT it did run fine for a little longer than usual before acting up. Someone told me that white electronic thing on the fender by the air box with the 2 wires going to it is a resistor for the pump and I should try replacing it.

I'm ready to just wire it to a switch with a hot wire switched on by the ignition.

That is the fuel pump ballistor resistor. You could always jump a wire between there and see if it changes anything, then you know if its bad or not. Are you sure all your hose clamps are on tight and no cracked lines? It could be drawing air from somewhere. I believe the 95s have the fuel pressure regulator in the tank? Have you checked that out yet or replaced it?

The fuel pump ballast resistor was eliminated in 95 per the FSM.

If you have one on the driver's side fenderwell, just bypass it with a jumper wire.

Good luck.

I have yet to actually look and see if the ballast resistor is there. I sure know there is one on my 89 XJ.

I have not checked into the fuel pressure regulator yet either. Those are vacuum operated aren't they? That would explain why hill climbs or other things with high rpms are problematic.

luvherinmyjeep32 said:

I have yet to actually look and see if the ballast resistor is there. I sure know there is one on my 89 XJ.

Yeah, still have mine on the 90--"if it ain't broke..."

I have not checked into the fuel pressure regulator yet either. Those are vacuum operated aren't they? That would explain why hill climbs or other things with high rpms are problematic.

Click to expand...

Yes, you should have 31 psi vacuum attached, 39 psi without vacuum.

Update

Wired the fuel pump with a constant power once the ignition is on.

Took it out, crossed the creek, ran up the hill, came back down the hill...all good...crossed the creek again (slowly) and it started doing it's old thing! Now it must be an issue with the tank or pump or ground? I swapped the pump with another one I had laying around. I was thinking that maybe the baffle in the tank is keeping fuel away, but I was going downhill till I hit the creek so there should be plenty of fuel on the side of the baffle that the pump is on, the downhill side.

Ah!

Oh, and I did not check the vacuum on the pressure regulator...forgot about that...but I did look at the hose and it appears to be in good conditions, no cracks or anything.