Fuel Pump Issue or not?

92 Sport, 4wd, 4.0L

On Monday, a high pitched squeal began emenating from the rear of the vehicle, somewhere in the vacinity of the gas tank. It sounds like the brief sound hear when the fuel pump engages when you first turn the key, only it is continuous and not as loud.

My son drove the truck Monday and Tuesday with no problems. On Tuesday evening, he lost power while under steady acceleartion on a flat surface. It sputtered for a minute and then came right back.

I did the search thing and found three schools of thought:

1. It is the fuel pump and it is going out, so I had better replace it.
2. It is the fuel pump and all of them make this noise and I have been driving mine for years, so don't worry about it.
3. It's got nothing to do with the fuel pump, it is somewhere else in the fuel system. Most probably _________ (insert one: relay, ballester, hose, clamp, filter, intake, TPS, CPS, NSS, ABC, EIEIO)

I tend to lean toward 1, since it hasn't been making the noise and the truck did sputter and I always follow Ocam's adage - entities should not be multiplied beyond necessity.

I don't doubt that there are Jeeps out there that whine all the time, but this one has not been doing that...

What is the general opinion - should I go ahead and replace the fuel pump or let it ride until it doesn't?

I'm not clear on the symptom. You state the noise you here: "-- It sounds like the brief sound hear when the fuel pump engages when you first turn the key, only it is continuous and not as loud." The pump noise should be constant. You say it sounds "normal" when you turn on the key (first 3-sec), but sounds the same, only quieter when it's running? That sounds normal, to me. I can barely hear my pump run, when the engine is running. Generally, a noisy pump indicates possible imminent failure. It gets much louder as time goes by. It's possible you have a partially clogged fuel filter, putting stress on the pump. A better description of the noise variations, and when they occur would help.

There is no noise variation, just a noise where before there was not one. It seems that you fall into the "mine always makes a noise camp?" This Jeep never made a discernable noise after the initial brief sound when the key is first turned. Now, it is making that sound constantly.

I can see where a clogged filter might be causing the pump to work harder - I'll check that next.

Thanks for the reply.

I'm of the impression that the pump doesn't get quieter just because the engine is running. I beleive the same voltage is applied to the pump when you first turn on the ignition key as there is while the engine is running. During cranking, the "ballast" resistor is bypassed to give full battery voltage to the pump, then allowed to reduce the voltage to reduce noise. So, I'm not really in the "mine has always made noise" camp, but yes, they all do. Are you changing your first account to say it gets noisier after the engine starts?

he is saying that where you could only hear the pump go "bzzzzzzzzzzzzzzzzzzzz" when you turn the key to the on position for a couple seconds, now he can hear it constantly, and IN the cab.

i actually have the same issue. its definately noticible, however i have no insulation or carpeting, so it may just be because of that....

ive been told that constant, noticible noise is an indicator of its iminent demise.. you probably have a little while, but its getting there.

Rocklandxjer, you are absolutely correct. Before, you could only hear the initial "bzzzzzzzzz" when you turned the key. Now, there is a buzz all of the time. It wasn't there before, it is there now.


I also have no insulation or carpeting and haven't had any for a year or more. I don't think it makes any difference. The noise was not there last week, it is there now.

Also, the noise can be heard in the cab, outside the cab, and in a car travelling 30 feet behind the cab.

I am going to check the fuel filters for impeded flow and if that doesn't turn up anything I will most likely replace the fuel pump this weekend.