Fuel Pump Ballast Resistor Questions
01-09-2020, 02:36 AM
#31
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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.
01-09-2020, 07:25 AM
#32
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Year: 1995 RHD
Model: Cherokee (XJ)
Engine: 4.0l
If you have new connectors then certainly change the old corroded ones to fresh new ones. This shouldn't make anything quieter though as you're only improving the voltage to the pump by using clean connections.
01-11-2020, 06:04 PM
#33
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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.
01-11-2020, 06:06 PM
#34
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01-12-2020, 03:23 AM
#35
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Year: 1991
Model: Cherokee (XJ)
Engine: 4.0 6cyl.
Try this
Disconnect the wires from the ballast resistor and connect them together. Start the motor and if you still hear the same sound with it disconnected, either your ballast resistor is no good and passing all 12 volts to the pump, or you have a noisy pump. Hope this helps.
01-12-2020, 03:19 PM
#37
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Year: 1989
Model: Comanche (MJ)
Engine: 4.0
The ballast resistor makes a great place to check if the fuel pump is getting current, btw. I measured mine recently while troubleshooting a no-start to check if the fuel pump was running. The voltage at the resistor drop to zero a few seconds after key-on and no voltage while cranking - which meant the computer wasn't seeing the cranking which led me to the CPS sensor. Once running, I had 13.5 volts on one wire, and 9.5 volts on the other (I think the resistance is somewhere around 1.2 ohms, so that makes it about 3 amps).
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BlueRidgeMark (01-13-2020)
01-13-2020, 08:24 AM
#38
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06-30-2020, 04:49 PM
#41
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I've replaced a few fuel pumps in the XJ over the last 23 years. Never replaced the Ballast. I installed one fuel pump that was terribly loud all the time. It lasted about 4 years. I Installed another fuel pump two years ago and it is quiet. The only thing I hear is the initial fuel line prime when turning the key to the on position.
Here's a tip: turn the key to on position, wait for the fuel prime, then turn the key to the start position. That technique will cut out the couple extra seconds on the front end of the engine cranking over.
Here's a tip: turn the key to on position, wait for the fuel prime, then turn the key to the start position. That technique will cut out the couple extra seconds on the front end of the engine cranking over.
06-30-2020, 04:59 PM
#42
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I've replaced a few fuel pumps in the XJ over the last 23 years. Never replaced the Ballast. I installed one fuel pump that was terribly loud all the time. It lasted about 4 years. I Installed another fuel pump two years ago and it is quiet. The only thing I hear is the initial fuel line prime when turning the key to the on position.
Here's a tip: turn the key to on position, wait for the fuel prime, then turn the key to the start position. That technique will cut out the couple extra seconds on the front end of the engine cranking over.
Here's a tip: turn the key to on position, wait for the fuel prime, then turn the key to the start position. That technique will cut out the couple extra seconds on the front end of the engine cranking over.
06-30-2020, 05:00 PM
#43
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Year: 1995 RHD
Model: Cherokee (XJ)
Engine: 4.0l
I'm guessing it was wearing out then. What once was made to tight tollerances had become a loose mess. A buzzing loose mess at that.
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