Loud fuel pump

[themangeraaad]

I searched and found what I think is my answer.. which is what I feared..

But 1993 XJ, 4.0, standard, etc

Fuel pump is loud on Hot days after running for a while. Its quiet on start up like it always was before, but now on hot days after I get back from work (45 min drive) and mostly after I get off the highway it has a relatively loud hum to it. Can I assume that it is on its way out, or does anyone have any other possibilities. I dont think its a clogged filter due to the fact that its only after running for a while on a hot day... or does anyone else have this issue and just ignore it and it hasnt led to any issues yet. I just want to fix it before I die on the highway if I need to, but if it will keep running fine w/ the whine i will ignore it for another wk or 2.

 

[DIGITRUCK]

Try a bottle of Fuel System Cleaner. Donno about your '93 but on my
'88, there is a fat rectangular resistor that was specifically designed to quiet the fuel pump.
Check it if it's there.

On mine, it's right next to the EGR Solenoid on the left fender under the hood.

Thx.

 

[prerunner1982]

mine hums all the time.. the PO said it has done it for 3 yrs... doesnt have any performance problems so I just go on. I have heard of people putting some tranny fluid in thier gas tanks to quite fuel pumps.. I havent tried it yet but would be great if it works..

 

[mjma]

It may be alright, or it may be on it's way out. Unfortunately there is only one way to tell....and that could mean being stuck on the side of the road.

As Prerunner1982 suggested, there is something that could potentially prolong it's life a little bit. I have thrown 2stroke oil into the gas tank in hopes of lubing up fuel pumps. If you've got some around, mix it in with some gas and pour it in, then see if that quiets it down at all.

Other than that, if it persists, you may want to change the fuel pump. Luckily, it's pretty easy on an XJ. If you can, I'd drop the tank to do it, but it can be done with the tank still up there.

 

[themangeraaad]

Well it should be a bit easier to get in there with the lift at all, so I am quite sure I can get in there. I might just pick one up tomorrow and keep it in the back, so if it does die before I replace it, I can do it on the side of the road. Might as well. But yeah, I used Marvel and its been doing its job, it only gets bad once in a while when its real hot out and its a long drive, and mostly when I drive a bit faster than I should, so I think I will just go with it and replace everythign esle first. I got bigger problems as of now, thanks for the help

 

[TMXONR]

My '87 had a loud pump. It got REAL loud on the trail. I went ahead and replaced it, and now I can only hear it if I try to hear it. I got my pump from the Dealership which was $215. From what I read it is best to get it from the dealership (if the origional pump lasted 20 years, its best to get another one that will). And with the lift I was able to sit under my Jeep while changing the pump. Just keep a fan going to blow the fumes out.

 

[Blaine B.]

On the later XJ's, the pump was put at the top of the tank....unfortunately

 

[themangeraaad]

Thank god I was poor and could only aford a beaten 93. And then over time could invest $$ into it to make it worthy of being on the street. I suppose I should just invest the time and money in replacing it. I think I will just wait until my next check comes in, since I already put $250 of my last one towards parts.

But anywho, TMXONR, how long of a process is it to do? Aka, could I do it real quick or is it something I should set a chunk of time aside for. I know the "theoretical" timeframe for completing it may be one thing, but with all the little problems you encountered (if any) approx how long should I expect to be looking at? And along the same lines, is there anythign else that doesnt come with the pump that I should expect to break/have to replace while doing this so I dont get half way through and have to start calling around for a ride to the parts store to pick up some random nuts or bolts or seals or whatnot?

 

[xjbubba]

Not sure of the 93, but I've changed the pump in my '88 3 times. With a lifted jeep, I think it's easiest to drop the tank. The pump fits into a grommet at the bottom. It could be a bear to get the pump into this grommet with the tank still installed. Plus, with the tank out, cleaning the inside would be a good thing, while you're at it. To drop the tank, there are two nuts, one on each side, at the front, that hold the tank up. They can be slow removing if you only have an open end wrench. I made a deeeeep socket, by cutting and old socket in half and welding a piece of pipe in between the two ends. My "new" socket and an air ratchet make dropping the tank "fun"!!
Syphon or pump out as much fuel as you can. The hardest part of dropping the tank is getting the fill and vent lines loose.
Once that's done, use a floor jack to help drop the tank, as you remove the nuts.
To remove the pump from the tank, you need a brass punch to remove the retaining ring from the tank; brass is for safety. You don't want a spark while your pounding away. Once that's loose, and all other lines are disconnected, lift up and rotate the pump assembly out, to the front. Be careful of the fuel level sender float, and insure the grommet is either stuck to the bottom of the pump assembly, or is still located in the hole at the bottom of the tank; it's a slip fit and could come out of the hole in the tank, and, fall off of the pump as it's removed.

 

[TMXONR]

But anywho, TMXONR, how long of a process is it to do? Aka, could I do it real quick or is it something I should set a chunk of time aside for. I know the "theoretical" timeframe for completing it may be one thing, but with all the little problems you encountered (if any) approx how long should I expect to be looking at? And along the same lines, is there anythign else that doesnt come with the pump that I should expect to break/have to replace while doing this so I dont get half way through and have to start calling around for a ride to the parts store to pick up some random nuts or bolts or seals or whatnot?

With all problems encountered and college. It took about 1 evening and half of a day. The problems I had were, my old battery cables not letting me start the Jeep up to test, and for some reason I had to run my pump backwards first to get it to pump. Because it wouldn't pump at first. If I had no problems it would have taken an evening or about 4 hours, since I had to lower the tank when I replaced the vents. If I just replaced the pump, I probably could have gotten it done in an hour or two. The big o-ring on the front of the tank was hard to get to stay in place (pick one up).

Sorry for the late reply.

 

[themangeraaad]

Not a problem, thanks for the help. Right about now I am sitting on the question of if I keep throwing time and money into the XJ or take it off the road and invest in a smaller, more comfortable car for driving 60+ miles a day for work and for sr year of college.. Keeping the Jeep of course, but just taking it off the road for the time being. Not quite sure what I am doing just yet.

 

[87manche]

My '87 had a loud pump. It got REAL loud on the trail. I went ahead and replaced it, and now I can only hear it if I try to hear it. I got my pump from the Dealership which was $215. From what I read it is best to get it from the dealership (if the origional pump lasted 20 years, its best to get another one that will). And with the lift I was able to sit under my Jeep while changing the pump. Just keep a fan going to blow the fumes out.

87's didn't have a ballast resistor to quiet the pump, so if it still seems loud to you there was a TSB ages ago on adding one.

 

[TMXONR]

The old one was a kind of loud that sounded like it was about to die or getting real tired, it was more like a whining noise. When I put the new pump in I can only hear it on start up if I don't have the radio on. Also, I didn't hear it once on the trail.

 

[themangeraaad]

So bringing back my own dead thread since I am trying to be lazy and cheap... but it was mentioned that throwing some 2 stroke oil in with the gas could lube up the pump and all, maybe quieting it down... 2 questions.. how much oil and could adding it potenitally damage anything else?