Loud humming, fuel pump?
Seasoned Member
Joined: Apr 2012
Posts: 254
Likes: 0
From: New Jersey and Maryland
Year: 1996
Model: Cherokee(XJ)
Engine: 4.0L
I'd agree it's worth a look. However... this is the one piece of work that I had done with my previous XJ. The pump was kind of loud, and like everyone else I figured it must be on its last legs. So I took it in to get done... ended up replacing the entire gas tank, too.
And the day that I got my Jeep back, with its brand new gas tank and fuel pump... it sounded exactly the same.
So yeah. Take it for what's it worth.
And the day that I got my Jeep back, with its brand new gas tank and fuel pump... it sounded exactly the same.
So yeah. Take it for what's it worth.
Thread Starter
Junior Member
Joined: Apr 2012
Posts: 92
Likes: 1
From: Portland, OR
Year: 88
Model: Cherokee
Engine: Inline 6 4liter
Thanks for the info. May replace it soon but I'm going to try running fuel injector cleaner through, and also change the fuel filter (a friend said it may be restricting the fuel in there so it hums?) since it was cheap I figured I'll go ahead and change that fuel filter - Doing that tonight.
In case this stuff doesn't work, anyone got a link to a dyi fuel pump replacement thread for newbies?
In case this stuff doesn't work, anyone got a link to a dyi fuel pump replacement thread for newbies?
Seasoned Member
Joined: Apr 2012
Posts: 253
Likes: 2
From: Abu Dhabi, UAE
Year: 1991
Model: Cherokee (XJ)
Engine: 4.0 6cyl.
the balast resistor located near the hood hindge on the drivers side fender, is there to drop the voltage to the pump from the full battery volts needed at start up for priming down to something less than full power so it won't be lous. so maybe check the balast resistor, should be about 1.3 ohms across the terminals and when it is running should be battery voltage on one terminal and about 11 volts or so on the other. if it is shorted or someone has by-passed it, that means the fuel pump is running full speed and will be loud and won't last very long. just a thought
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
Likes: 1,579
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
the balast resistor located near the hood hindge on the drivers side fender, is there to drop the voltage to the pump from the full battery volts needed at start up for priming down to something less than full power so it won't be lous. so maybe check the balast resistor, should be about 1.3 ohms across the terminals and when it is running should be battery voltage on one terminal and about 11 volts or so on the other. if it is shorted or someone has by-passed it, that means the fuel pump is running full speed and will be loud and won't last very long. just a thought
Junior Member
Joined: Nov 2009
Posts: 57
Likes: 0
From: Hurricane ut
Year: 1990
Model: Cherokee
Engine: 4.0
I just discovered on my jeep there is no charcole canister so the vent line from the tank was crimped shut so I re-cut the metal line and ran it into the the intake. and now the pump is much quieter.
Thread Starter
Junior Member
Joined: Apr 2012
Posts: 92
Likes: 1
From: Portland, OR
Year: 88
Model: Cherokee
Engine: Inline 6 4liter
So, I finally replaced the thing, because it almost got me stranded 300 miles from home as it wouldn't push me up hills and the jeep wouldn't go more than 55mph. It would start to shake and feel like there was no fuel in the tank when I was on full still, trying to get up to speed going home from my road trip.
Got the Napa one, which was Carter brand when I opened the package. Well, looks like the one that was in there was the same exact one - Oh well. Now I can go as fast as I want, that seemed to help the power problem, however.. the new thing is still quite noisy (a bit softer though). Whats odd is that when I got the jeep, the thing didn't hum. A month or two later, it did. This new one hums right away, but then again I still haven't filled my tank up yet and I hear that may make a difference.
BTW. My tank is 16 gallons. I ran it to fumes once then filled up; barely 16 gallons. SHould have 20 for an xj, I hear. Either jeep lies or the thing has been replaced - Do you think this would make a difference?
What is this ballast resistor business? (newbie here) For a $10 part, it sounds like it actually may help a lot? This guy was talking about a renix on Jeepforum having the loud noise: "Seriously though with a RENIX era Jeep it's likely your fuel pump ballast resistor gone south. You can put those two wires together to see if your pump works...or still hums...it's a $10 part."
In a few days I'll fill her up(it only has a quarter tank right now) and report back.
Got the Napa one, which was Carter brand when I opened the package. Well, looks like the one that was in there was the same exact one - Oh well. Now I can go as fast as I want, that seemed to help the power problem, however.. the new thing is still quite noisy (a bit softer though). Whats odd is that when I got the jeep, the thing didn't hum. A month or two later, it did. This new one hums right away, but then again I still haven't filled my tank up yet and I hear that may make a difference.
BTW. My tank is 16 gallons. I ran it to fumes once then filled up; barely 16 gallons. SHould have 20 for an xj, I hear. Either jeep lies or the thing has been replaced - Do you think this would make a difference?
What is this ballast resistor business? (newbie here) For a $10 part, it sounds like it actually may help a lot? This guy was talking about a renix on Jeepforum having the loud noise: "Seriously though with a RENIX era Jeep it's likely your fuel pump ballast resistor gone south. You can put those two wires together to see if your pump works...or still hums...it's a $10 part."
In a few days I'll fill her up(it only has a quarter tank right now) and report back.
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
Likes: 1,579
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
When you had the pump out, did you see the tapered rubber piece at the bottom of the unit? If that's missing, the fuel pump will be noisy.
Ballast resistors, when they fail, do not give more voltage to the pump to make them noisy. The fail giving little or no voltage.
And some Cherokees had a 16 gallon tank, sort of.
Ballast resistors, when they fail, do not give more voltage to the pump to make them noisy. The fail giving little or no voltage.
And some Cherokees had a 16 gallon tank, sort of.
Senior Member

Joined: May 2012
Posts: 925
Likes: 5
From: Fort Erie, CANADA
Year: 1987
Model: Cherokee
Engine: 4.0
How hard was it to get the old pump out and a new one in? Did you have to drop the tank to do it? Mine is moaning pretty loud too. Good pressure still.
::CF Moderator::
Joined: Aug 2011
Posts: 43,971
Likes: 1,579
From: Prescott, Az
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
Senior Member

Joined: May 2012
Posts: 925
Likes: 5
From: Fort Erie, CANADA
Year: 1987
Model: Cherokee
Engine: 4.0



