Fuel Pump voltage

[Comanchaholic]

Does anyone know what the voltage to the fuel pump should be? I'm getting 6 volts. Is this enough? [/img]

[comancheman]

does your truck run?

[KYMJ]

Can't answer that specifically. Can you hear the pump running? Mine wasn't running. My test light barely lit, I wished I had checked it with a voltmeter, but didn't. The ballast resistor was bad and the pump wasn't getting enough voltage. So, if your're trying to diagnose a problem that might help. If you just want to know, sorry.

[87manche]

cranking: 12V

 

running: about 8 or 9.

 

try bypassing the ballast resistor.

[JeepcoMJ]

cranking: 12V

 

running: about 8 or 9.

 

try bypassing the ballast resistor.

 

 

the ballast resistor is the ceramic piece on the left side of your engine bay, mounted to the sidewall...one wire in, one wire out.

[rdp001]

:brows: SO ANYWAY i HAVE HAD THE SAME PROBLEM YOU HAVE .AND i PUT STRAIT 12V TO MY PUMP(WITH FUSE!!) AND MY MJ NOW RUNS LIKE A Raped ape no more bucking and hesitations ,don t know what everybody else runs but mine runs a lot stronger then with the ballast resistor! :roll:

[HOrnbrod]

SO ANYWAY i HAVE HAD THE SAME PROBLEM YOU HAVE .AND i PUT STRAIT 12V TO MY PUMP(WITH FUSE!!) AND MY MJ NOW RUNS LIKE A Raped ape no more bucking and hesitations ,don t know what everybody else runs but mine runs a lot stronger then with the ballast resistor!

 

With a healthy fuel pump ballast resistor circuit, voltage at the pump should be 9-10 VDC after starting. The ballast resistor is bypassed during starting, then relayed in the circuit to drop the voltage to prolong the FP lifespan and hold noise down. Corrosion on the relay terminals, the ballast resistor, and the pump itself will cause a voltage drop, and cleaning them up will correct this. A raped ape will run only so far, then it dies from exhaustion :cheers:

[rdp001]

Hornbrod I like your reply ,it is kinda like ....... life sucks then you die :bowdown: :bowdown: :bowdown: Anyway Ilike the way you say " with a healthy" mine is an 88 with the Renix on it, have been doing nothing but fixing and repairing!!! I know Jeep could have done better then this . :brows:

[87manche]

Jeep did pretty well, how many 20 yr old vehicles are even repairable at this stage.

 

let alone to see the abuse I put mine through.

[Comanchaholic]

OK ,I cannot find a ballast resistor any where,and where is the fuel pump relay and what does it look like?

[Eagle]

Hornbrod I like your reply ,it is kinda like ....... life sucks then you die :bowdown: :bowdown: :bowdown: Anyway Ilike the way you say " with a healthy" mine is an 88 with the Renix on it, have been doing nothing but fixing and repairing!!! I know Jeep could have done better then this . :brows:

Don't blame Jeep for what a previous owner broke, or failed to maintain.

 

My '88 XJ I bought new in early 1988. It has just over 266,000 miles on it now. The original clutch lasted 204,000 miles, and was replaced only because the release bearing got noisy. The original Trac-Lok lasted 150,000 miles. The valve cover has never been off. I'm just about to put in the second replacement radiator, but the original lasted something like 185,000 miles (in New England). I've replaced one front hub/bearing unit -- the other is still the original. All driveshaft u-joints are original.

 

There's nothing wrong with your Jeep. Fault whoever didn't take care of it before you got it.