Fuel Pump
- Thread starter Grover
- Start date
MountainD
Technical Excellence Contributor
for me, intermittent and brief bucking and even stalling particularly, on freeway. I think older fuel pump may get too hot particularly when low on gas since it’s not submerged and gets intermittent? Not fully sure. Most failures fail to off Which makes it mildly easier to diagnose…. I will say, some folks think they fixed it when it was corroded connectors and pump loosing power— they swap pump and think it’s fine and dons address the shitty wiring…. Argh…wiring. Also pump gets blamed all the time for bucking when it’s not as bucking has a lot in common with other diagnosis. Again, most time it just fails
TexasDefender110
Member
The initial symptoms of my failing fuel pump included having to prime the fuel system with the ignition at least twice after the truck sat overnight. More throttle was required for acceleration. With the pump failing the truck is probably running lean.
MountainD
Technical Excellence Contributor
The priming is also a symptom of the drain back check valve internal to the pump failing and/or a fuel one leak. Also a leaking injector sometimes. Most leaks like this tend to occur internal to the tank with the accordion hose from pump to fuel pipe connection, either with a loose clamp or pinhole prick. I actually put a check valve (redundant) external at tank to take additional strain off system. I don’t trust quality of new pumps check valve as I’ve returned 2x of the LS pumps for that reason.
My understanding is that the original pump is NLA. I’ve got the proline one in my D90
Z.G
Well-known member
Correct, the original is obsolete unfortunately
Frobisher
Well-known member
Related to this topic, my fuel pump (3.9L 14CUX as original post) has been staying on after shutdown for several minutes and it seems like maybe it's getting a bit louder as well. Might this be a combination of dying pump and/or bad relay? Fuel filter is about 6 months old.
It should not be happening. You may want to check out the relay - or, at least, make sure the pump is actually running when the ignition is off.
Frobisher
Well-known member
I can hear the pump humming after shutdown, usually after a longer drive. It doesn't happen if I only have it on for a few minutes. I don't think there's anything else that hums in the back by the gas tank, hence the guess at the pump. I'm going to check the relay tonight if possible.
Frobisher
Well-known member
I never thought about cleaning the cap, so I googled it to see what to do. Aside from cleaning the threads, rim, and the rubber ring, what else should be checked? I was reluctant to spray directly into the cap since I don’t know what all goes on inside. Thanks for the suggestion; it makes sense.
Unless it is the old style cap, it shouldn’t be venting to atmosphere