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Loud humming, fuel pump?

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Old 04-29-2012, 04:54 PM
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Default Loud humming, fuel pump?

This is my first post and I'll start by saying I am basically a newbie when it comes to cars. My 88 xj has 153000 on it, and I've put at least 1,000 on (fairy new to me, like 1 month). Before me it wasn't used very much, just as a utility vehicle.

Anyways, after going like 30 minutes it starts to hum, back of the car, and my friend said it is probably the fuel pump going bad. Any idea if this is true, and if I should fix it... Easy enough for a beginner to do with some specific guidance? I wil be taking it on 400 mile treks in the next 2 months so I need it running properly.

Should mention that for the first several hundred miles, it didn't do this
Old 04-29-2012, 05:02 PM
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napa sell hole assembly right at 100 bucks best buy in my opinion ,hummmping means im getting old
Old 04-29-2012, 09:12 PM
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Thanks, and should I replace it then, or wait until it fails like my friend said?
Old 04-29-2012, 10:55 PM
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Originally Posted by 88cherokeepyles
Thanks, and should I replace it then, or wait until it fails like my friend said?
Depends. Where and when are you going to be when it fails? Add tow bill to price of fuel pump.............
Old 04-30-2012, 12:44 AM
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Are you certain it's the fuel pump? Is it a constant hum, or does it change when you speed up, slow down, stop?
Old 04-30-2012, 01:22 AM
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Does not change pitch. It continues when it is in park, and will continue if it is re started any time soon thereafter. I do not know if it is a fuel pump. Hoping someone could help me out with that. I think in that case, cruiser54... knowing my luck I'd be hundreds of miles away... lol. Hoping for the best of course.
Old 04-30-2012, 01:50 AM
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Originally Posted by 88cherokeepyles
Does not change pitch. It continues when it is in park, and will continue if it is re started any time soon thereafter. I do not know if it is a fuel pump..
I'll bet it is. That's about the only thing in the rear that whines when stopped. Unless you have kids back there, lol.

Just wanted to make sure you weren't hearing differential or drivetrain, or some other sort of whine. ITA on replacing the pump before it leaves you stranded.
Old 05-01-2012, 09:16 PM
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mine has always hummed loudly worse in the summer I have changed it 3 times and all 3 sounded the same, put more padding under the rear carpet it helps
Old 05-01-2012, 09:21 PM
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Originally Posted by swells
mine has always hummed loudly worse in the summer I have changed it 3 times and all 3 sounded the same, put more padding under the rear carpet it helps
What brand of fuel pump are you using?
Old 05-01-2012, 09:29 PM
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when I bought my XJ the fuel pump hummed, but it ran fine. after a few weeks, I punched it to pass someone and it just kinda sputtered and wouldn't go any faster. replaced the fuel pump and its good to go. its not the easiest thing to replace, but its not a huge deal. make sure you get the pointed rubber end on the end of the pump, into the raised holder for it inside the tank.
Old 05-01-2012, 10:15 PM
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my fuel pump has hummed since I got it... 4 or 5 years ago. The previous owner said it had been humming for a couple years prior to that. knock on wood. I been told a couple times to run some transmission fluid through the tank and it will lube the pump and quiet it down. Haven't tried it yet.
Old 05-01-2012, 10:40 PM
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Originally Posted by prerunner1982
my fuel pump has hummed since I got it... 4 or 5 years ago. The previous owner said it had been humming for a couple years prior to that.
hahahaha, the PO of my jeep told me the same thing
Old 05-02-2012, 12:44 AM
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Originally Posted by prerunner1982
I been told a couple times to run some transmission fluid through the tank and it will lube the pump and quiet it down. Haven't tried it yet.
I've never heard of that before. But it sounds like a very bad idea
Old 05-02-2012, 12:55 AM
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Originally Posted by prerunner1982
my fuel pump has hummed since I got it... 4 or 5 years ago. The previous owner said it had been humming for a couple years prior to that. knock on wood. I been told a couple times to run some transmission fluid through the tank and it will lube the pump and quiet it down. Haven't tried it yet.
Marvel mystery oil works wonders!
Old 05-02-2012, 09:22 PM
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Originally Posted by 1996sportXJ
I've never heard of that before. But it sounds like a very bad idea
Never worked for a shady used car dealer, have you.
Adding a quart of trans fluid to a full tank sometimes quiets a fuel pump that's on it's last legs. Temporarily.
It fixes nothing and isn't worth bothering with if the pump is going bad. Just replace it before you end up stuck somewhere.


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