Fuel Pump Ballast Resistor Questions
#16
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I'm changing the ballast because my fuel pump is making a humming noise. I believe it is the ballast.
#17
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Year: 1989
Model: Comanche (MJ)
Engine: 4.0
Yes. the resistor is in series with the fuel pump. It's there to reduce the voltage and noise from the pump when running. When cranking, the resistor is bypassed to give the pump full voltage. As mentioned it can be eliminated if you connect the remaining wires together.
It's normal to hear some noise from the fuel pump.
It's normal to hear some noise from the fuel pump.
#18
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#19
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Yes. the resistor is in series with the fuel pump. It's there to reduce the voltage and noise from the pump when running. When cranking, the resistor is bypassed to give the pump full voltage. As mentioned it can be eliminated if you connect the remaining wires together.
It's normal to hear some noise from the fuel pump.
It's normal to hear some noise from the fuel pump.
#20
Old fart with a wrench
The resistor is there to reduce the voltage that the pump runs at when it's got a constant fuel flow to make it last longer, not just make it quieter. You can bypass it until you get a new one, but I wouldn't run it that way forever. Not unless you enjoy changing pumps!
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#28
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Year: 1989
Model: Comanche (MJ)
Engine: 4.0
#29
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Year: 1991
Model: Cherokee (XJ)
Engine: 4.0 6cyl.
best way to avoid the connector corrosion at the balast resister is to put heat shrink tubing over the wires, then solder the wires to the tabs on the balast resister,. then slide the heat shrink tubing over the tabs and shrink the tubing with a lighter, it makes a nice tight seal that lasts longer then you'll own the car.
#30
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Year: 1991
Model: Cherokee (XJ)
Engine: 4.0 6cyl.
I agree it is your balast resistor. the resistor is bypassed during start up so the pump gets full 12 volts. after the engine starts, the balast resister is now in the curcuit and drops the voltage down to something less than 12 Volts so as to make the pump last longer and not be so loud running full forse. when the balast resister goes bad it can either open up, causing your enging to stop running, or the resistance will decrease causing the pump to have full 12 volts. so I would suggest changing the ballast resister, they are cheap and available on E-Bay or a auto parts store. I'm sure that will solve your problem.