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OEM Tech Discussion Forum for OEM (Original Equipment) or stock XJs and MJs. |
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#1
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I have a 93 XJ that I just bought. The fuel pump was humming when I got it. The jeep runs good but I noticed today that when I turn anything else on the humming gets worce and it also affects the volts gauge. Can somebody please help.
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#2
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Re: Fuel pump humming
Teach it the words?
Have you checked the voltage to the fuel pump? |
#3
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Re: Fuel pump humming
Has the fuel pump been replaced? Is it an Airtex unit? If it is, these are normal to hum, gets louder the warmer it gets. Bosch or OEM seems to be the only way to go.
If it affects the voltage, it's very possible its on its way out. If you take it out to diagnose, be prepared to replace. Let us know what you find. |
#4
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Re: Fuel pump humming
Output fuel line on the fuel pump, inside the gas tank may be going bad, leaking. My 89 Renix is noisy when it gets down to 1/3 of a tank of fuel. Quite as a church mouse with a full tank.
Is it a lifted jeep or stock?
__________________
Quote=8Mud: "Go ahead and put up the best fence you can build, I'll bet on some Mexican with a few dollars of nails and a pile of scrap lumber." 34 MPG ![]() ![]() |
#5
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Re: Fuel pump humming
Quote:
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#6
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Re: Fuel pump humming
I think they get hot and confused, start thinking they are Hummers, instead of Jeeps?
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__________________
Quote=8Mud: "Go ahead and put up the best fence you can build, I'll bet on some Mexican with a few dollars of nails and a pile of scrap lumber." 34 MPG ![]() ![]() |
#7
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Re: Fuel pump humming
mine goes from quiet to loud often i get worried when i cant hear it.
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#8
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Re: Fuel pump humming
They will be loud if the rubber bumper falls off the bottom of the unit upon installation.
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#9
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Re: Fuel pump humming
Check to see if the fuel pump resistor has been removed (or by-passed) by the previous owner. It's a white ceramic oblong-looking thing with 2 wires connected to it, and it's
mounted on the inner fender, driver's side, in the engine compartment. Ordinarily when you first turn the ignition ON, the fuel pump is given 12V DC for (only) a second or two in order to build up fuel pressure. After the engine is started and running, the fuel pump is given about 6V DC that comes through the fuel pump resistor. Some owners will sometimes by-pass or eliminate that resistor as a "shade-tree fix" for a fuel pressure problem. The downside of that "fix" is that the fuel pump is then running at 12V DC at 100% of the time (= spinning faster; is more noisy; wears-out faster). |
#10
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Re: Fuel pump humming
I should add that while mine is only noisy when the gas level is below 1/3 tank, it is also only noisy enough to hear at about 40-60 mph on the 89 Renix. I thought it was bearing noise at first. And it is as quiet as a church mouse while priming before I crank it.
__________________
Quote=8Mud: "Go ahead and put up the best fence you can build, I'll bet on some Mexican with a few dollars of nails and a pile of scrap lumber." 34 MPG ![]() ![]() |
#11
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Re: Fuel pump humming
Quote:
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#12
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Re: Fuel pump humming
And it is probably closer to 10-12 volts with the alternator running at 14.6 V?
__________________
Quote=8Mud: "Go ahead and put up the best fence you can build, I'll bet on some Mexican with a few dollars of nails and a pile of scrap lumber." 34 MPG ![]() ![]() |
#13
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Re: Fuel pump humming
More than likely. The resistor just "takes the edge off" the pump RPM.
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#14
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Re: Fuel pump humming
Is it necessary to drop the tank when installing the fuel pump? 92 XJ 4.0 thanks
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#15
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Re: Fuel pump humming
Nope
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