Hi guys, new here. So I am working on my parents 01 Grand Cherokee laredo 4.0l and it has been sitting for a while and I am afraid I may have damaged something trying to charge it. The battery cables were loose and the charge went into the electronics but I am not convinced this is what is causing this issue. The truck turns over but doesn't have any fuel pressure. I probed the relay slot and there is power before the relay and the coil is getting power *I THINK*( I do not hear a click though and I have tried swapping relays with no change). Now, I think all of the fuel had evaporated from the tank and I didn't notice before when I was trying to crank it so I don't know if that could've caused issues or not. I have filled it with gas but the fuel pump doesn't seem to be energizing. What should I check? How many fuses should there be?
P.S. I came down to NC from MA to work on this and am only down here till Sunday
If the battery sat very long dead it's probably shot. To check for spark shoot some starting fluid down the throttle body and if it starts until the starting fluid runs out you have spark.
I'd say check the wiring connector on the fuel pump for 12V in front of the tank if you can get to it. Afraid I can't help you with the fuses for powering the fuel pump since they may be different than my 04 4.7. The ASD relay should supply power to the fuel pump relay. Good luck.
So will jumping the fuel pump relay do anything then? And the battery has 1 cell dead it seems, stays at about 11.9 volts and is just strong enough to crank it but I have been using a lithium jump starter to augment it and it has been cranking at full force. Should the fuel pump have 12V constantly at the connector with key on?
If you've for sure got a dead cell in your battery, start there. These WJs are very sensitive to voltage. When your Crank Position Sensor fails, it sets a "no fuel" condition in your PCM. So your fuel pump won't get a signal from the PCM.
Buddy, I'd definitely start with a new battery. That will at least reset your PCM while your at the store. Make sure your battery connections are strong and clean. Report back and we'll keep trying to help.
Buddy of mine has a 99 WJ and actually never found his fuel pump issue. He even took a fuel pump and tank from a jeep i had that ran, didn't work finally ran a separate switch for power and fired right up. I work at an auto parts and also have had 10 jeeps, i have yet to sell a fuel pump for one, or need one myself (not to say they don't go bad, old fuel will ruin a pump after sitting for a few years)
Not to contradict you but there's quite few over on the ZJ forum who have had to change their fuel pumps. May be the older age of them vs WJ's but know my 96 ZJ had a TSB issued where the fuel pump is known to overheat/fail. Sure enough I had to replace it 4-5 years ago. On the other hand the 24 year old OE fuel pump in my 93 XJ still works good, knock on wood.
One of the problems in letting any vehicle sit is the location it's parked in. Rodents can create real havoc in chewing wires, hoses, and anything else they can get their teeth on!
And actually they don't need to sit long. Below is my 04 4.7 daily driver fuel pump wire harness last Fall. Sometimes living in the woods has it drawbacks and some psycho bushy-tailed rat decided to take out it's frustrations on my pump wiring harness! Real nice!
Not to contradict you but there's quite few over on the ZJ forum who have had to change their fuel pumps. May be the older age of them vs WJ's but know my 96 ZJ had a TSB issued where the fuel pump is known to overheat/fail. Sure enough I had to replace it 4-5 years ago. On the other hand the 24 year old OE fuel pump in my 93 XJ still works good, knock on wood.
(
Hey they sell after market pumps for a reason, cant say its not his case. I just know from MY experience its doesn't seem to be a "common" problem on the WJ's. I will say you can NEVER rule anything out. But i do know that old fuel in a tank will destroy a pump regardless. Far as a cute little chipmunk >. That can happen at any time sadly just i can see a woods being a more "common" place for that
Does the forum not have an edit function? Anyway, it was parked on soft ground with leaves and stuff piled up so I'm pretty sure a chipmunk or squirrel got up in there, judging by the bite marks it was a chipmunk. Stupid furry rodents...... That explained the fuel gauge on E and why sometimes it bounced up a bit, they also chewed through the level sending unit wires so I thought it was out of gas.
That sure looks familiar and dam rodents! I've had to cover all my wiring with that plastic convoluted tubing which slows them down a bit. And usually they don't like the taste of 'Scotch 33' electrical tape.
Maybe they changed things on the WJ's but on previous years they used a sugar based adhesive on on the friction tape on wiring harnesses. Nothing like drawing the rodents in and they rip that stringed friction tape to pieces for the sugar in the adhesive.
Well at least you figured out the problem and hope you got it running good again!
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