tmanhollister Posted October 4, 2009 Posted October 4, 2009 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.
CWLONGSHOT Posted October 4, 2009 Posted October 4, 2009 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
tmanhollister Posted October 4, 2009 Author Posted October 4, 2009 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.
Automan2164 Posted October 4, 2009 Posted October 4, 2009 Ideally should have battery voltage at the pump... 12V or better. A lot of member have problems with the ground on these trucks. There is a bed to chassis ground in the tail light housing I would also reccommend checking. Rob L.
HOrnbrod Posted October 4, 2009 Posted October 4, 2009 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?
tmanhollister Posted October 4, 2009 Author Posted October 4, 2009 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.
Automan2164 Posted October 4, 2009 Posted October 4, 2009 The ballast resistor is a quick fix, and often goes bad also. Rob L.
tmanhollister Posted October 4, 2009 Author Posted October 4, 2009 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
Automan2164 Posted October 4, 2009 Posted October 4, 2009 What about if you ran a lead back to the batt? Would you end up with 12V at the pin? Rob L.
tmanhollister Posted October 4, 2009 Author Posted October 4, 2009 What about if you ran a lead back to the batt? Would you end up with 12V at the pin? Rob L. from the ground pin to the pos. side of battery? or power pin to ground side of battery? didnt pay attention in my electrical class. ha.
Automan2164 Posted October 4, 2009 Posted October 4, 2009 Pos on the pin, ground on neg of battery... Sorry. Rob L.
tmanhollister Posted October 4, 2009 Author Posted October 4, 2009 Pos on the pin, ground on neg of battery... Sorry. Rob L. same as when going from pin to chassis/pin ground. I'm checking these volts with the key in the on position with the motor off and I'm not cranking it.
Automan2164 Posted October 4, 2009 Posted October 4, 2009 Not really. If the problem IS the ground, just grounding it through the ground pin or the chassis, would produce the same bad results. Rob L.
tmanhollister Posted October 4, 2009 Author Posted October 4, 2009 Not really. If the problem IS the ground, just grounding it through the ground pin or the chassis, would produce the same bad results. Rob L. oh i was saying that i checked it with the ground to the battery and it had the same results as when i was checking it at the other grounds.
Automan2164 Posted October 4, 2009 Posted October 4, 2009 Ah, sorry. So at least that outrules the ground. Now start looking to see why the pos has low volts. Probably a bad connection... Rob L.
tmanhollister Posted October 4, 2009 Author Posted October 4, 2009 Ah, sorry. So at least that outrules the ground. Now start looking to see why the pos has low volts. Probably a bad connection... Rob L. yeah ill check it out. should the relay be switching so fast though? it stops after like 10 seconds..
HOrnbrod Posted October 4, 2009 Posted October 4, 2009 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.
tmanhollister Posted October 5, 2009 Author Posted October 5, 2009 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.
Oizarod115 Posted October 5, 2009 Posted October 5, 2009 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?
Oizarod115 Posted October 9, 2009 Posted October 9, 2009 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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