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fuel pump died?


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drivin around today after i get my alignment and i take off from a stop sign and my mj turns off on me. it was pretty sudden not like a running out of gas situation. i get to the side of the road and i try starting it again. no luck. my question is if the fuel pump goes out will the jeep die quick or sputter then die. also i don't remember how loud the fuel pump was...would i be able to hear it when i turn the key to on? any help would be great guys.

 

thomass.

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Yes you should be able to hear the pump when you first start the truck.. BUT, if the system is up to pressure you will NOT hear it for more than a short second. Give it another try this AM and if its bad you will not hear it run. Overnight should be plenty sufficient for the system to depressurize enough to hear the pump.

Also check the ballast resistor on the DS front fender. Its the white/off white ceramic looking thing with a wire going into each end.

 

Good luck,

CW

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checked voltage at connector, one was ground and one had 7.5 dcv and one had 8.5 dcv. shouldnt this be higher? also when the key is turned to on one of the relays switches on and off really quick, and when i unplug the connector it doesnt click anymore. and i can hear a noise coming from the tank. its not the pump running but some clicking noise. just want to make sure its the pump.

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Yes, that is low, if your meter is accurate. How did you check the voltage at the connector? It should be checked w. the negative lead on the ground pin and the positive lead on the hot pin - this is what your pump sees for voltage. Them do the same check using a good chassis ground point for the negative lead. If the voltage reads higher, then you most likely have a bad ground. And what year is your rig?

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Yes, that is low, if your meter is accurate. How did you check the voltage at the connector? It should be checked w. the negative lead on the ground pin and the positive lead on the hot pin - this is what your pump sees for voltage. Them do the same check using a good chassis ground point for the negative lead. If the voltage reads higher, then you most likely have a bad ground. And what year is your rig?

 

 

ill check that. its a 89. i bypassed the ballast resistor and the pump sounds like its working now somewhat. but the relay is still switching super fast.

 

edit: actually its sounds pretty much the same.

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Yes, that is low, if your meter is accurate. How did you check the voltage at the connector? It should be checked w. the negative lead on the ground pin and the positive lead on the hot pin - this is what your pump sees for voltage. Them do the same check using a good chassis ground point for the negative lead. If the voltage reads higher, then you most likely have a bad ground. And what year is your rig?

 

 

just checked. voltage is same at pin and chassis ground. and with the ballast resistor bypassed it still won't start. ballast resitor ohm'd out at 1.6

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just checked. voltage is same at pin and chassis ground. and with the ballast resistor bypassed it still won't start. ballast resitor ohm'd out at 1.6

 

1.6 ohms is about right and it sounds like your ground is okay at the pump connector. What is the voltage on the ballast resistor terminals? It's a straight shot from the ballast resistor to the pump. If it's close to battery voltage, the low voltage at the connector might be caused by corrosion on the connector or the ballast resistor terminals. If the voltage is still low at the ballast resistor, swap out the chattering fuel pump relay.

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just checked. voltage is same at pin and chassis ground. and with the ballast resistor bypassed it still won't start. ballast resitor ohm'd out at 1.6

 

1.6 ohms is about right and it sounds like your ground is okay at the pump connector. What is the voltage on the ballast resistor terminals? It's a straight shot from the ballast resistor to the pump. If it's close to battery voltage, the low voltage at the connector might be caused by corrosion on the connector or the ballast resistor terminals. If the voltage is still low at the ballast resistor, swap out the chattering fuel pump relay.

 

i don't remember what the voltage was but i know it wasnt anywhere near 12. ill buy a new relay tomorrow and keep this updated.

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1.6 ohms is about right and it sounds like your ground is okay at the pump connector. What is the voltage on the ballast resistor terminals? It's a straight shot from the ballast resistor to the pump. If it's close to battery voltage, the low voltage at the connector might be caused by corrosion on the connector or the ballast resistor terminals. If the voltage is still low at the ballast resistor, swap out the chattering fuel pump relay.

 

i'm not calling BS or anything but i gotta ask someone else to do it... i yanked the wires off my ballast resistor in efforts to keep the pump from spewing gas out everywhere when i ran the starter while i had the fuel lines disconnected... the pump stil ran. pulled the pump relay by the coil... still ran, pulled ALL 4 relays and it pumped out fuel. :hmm: are you absolutely sure the truck wouldn't run with the ballast resistor unplugged?

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you have tried jumping 12v to the pump and making sure it actually works correct?

 

at that point if it indeed works, you need to chase wiring, get a meter and start at the fuel pump connector and work backwards from a wiring diagram til you find where its losing voltage at.

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