fuel pump?

Ok so heres my issue this week. I was out yesterday with a group of jeepers and my jeep had been dropping down to under 500RPMs then shooot back up and idle fine. Then the damn thing just died and wouldnt fire back up. the engine would turn over but was getting no fuel. the pump wouldnt prime so with that going on i am assuming the fuel pump is bad. we disconnected the battery to reset the ECU and no dice. then i we got a test light and placed in on the wireing harness leading to the fuel pump light never came on. so once again i am thinking fuel pump, but i would like to get another opinion on all this. thanks in advance for the help folks.

91XJ 5Sp np231 3inch lift with 33 MTRs. 210K on chassis and 100K on motor

It's possible that you have no power going TO the fuel pump and that your fuel pump is okay. Have you checked the fuel pump relay yet? Should be one in the PDC; the power distribution center under the hood on the passenger side. Swap it with another relay to be sure that isn't the culprit; these relays are all the same part number so no problem with swapping. Verify all fuses as well.

Might also want to verify spark while you are troubleshooting. Some problems will kill both spark and fuel.

yea we swithched out a relay and checked fuses. we didnt look to far into those since it was spuddering before and a fuse/relay would have just killed it. i never thought of checking the spark. i am going up with a buddie after work to look at it. he is a bit more jeep savy then me. hopefully its not the pump and something a bit more simple. also i have done a few searches and have found that it could be the ignition switch also

Have you bypassed the ceramic ballast resistor on the driver's side inner fenderwell?

Typically in the renix XJ's if they will spin, but won't fire up, the first thing I check is the CPS wiring, as this wiring harness always has gremlins in it, especially when the engine bay is warm.

I am guessing you checked the pressure in the fuel rail (there's a bleeder on the front under a little metal cap, drivers side near the front of the rail and next to the pressure regulator) if I need to check it, I just put a rag underneath/around it, and press it in with a pen if fuel doesn't squirt out (ig in run position) then it's a pump/lines issue.

As others have said, check the fuel pump relay (you can also hot-wire a bypass on the relay) and then check the ballast resistor (it's the white spaceship looking thing bolted to the driver's side fender well next to the air-box) first with a multi-meter, and then with the FP relay jumpered, try jumpering past the resistor and see if the FP comes on.

If all this looks ok, but you're still not getting pressure, check your fuel filter, it's easy to get to and replacing it is less than $10 at most autopart stores, and it never hurts to have a clean filter.

As a last resort, get underneath, and try applying 12v direct to the fuel pump, you should hear it come on, if it doesn't then yea, the pump may be bad. Otherwise you may have an electrical issue in the feed wires and will have to check continuity on all of them.

when all this happened the FP wasnt priming with a turn of the key. i will check all these things that yall are saying as well. aslo how do you skip past the resistor or hot wire a relay

also ive read of the CPS going bad when hot but we let it sit for a few hours and came back still same issues

To hotwire the FP, there is a relay on the passenger side, I think it's the 2nd one back (sometimes it's located under a panel) if you look at the bottom of the relay there is a switch electrical symbol, jumper the two sides of the switch (I will follow up later with pictures, working on another issue ATM).

If the CPS wiring is going bad (I've never actually had a bad CPS) grab the wiring harness and shake it, try to start, repeat. If this is actually the issue, cutting the wires back a few inches and then putting on a new connector is the best solution.

well me and a freind diagnosed it yesterday its getting plenty of juice 12.5v. and that at the connection so we have it down to the FP actually being bad. the fuel pump So i am going to buy a FP, lock ring, gasket and fuel filter today and heading up to get it fixed.

the FP primes but no where near like it should very short and quiet compared to before.

The hose between the pump outlet and the bulkhead fitting inside the tank maybe bad. Been a lot of reports of them going bad, suspect the ethanol fuels and age are killing them.

well i changed the FP and it fired right up. still noticed a little stuttering maybe a TPS or something like that. the old pump didnt have the strainer on it.

Then some trash may have gotten into the fuel pressure regulator on the fuel rail and the inlet filter screens on the fuel injectors, unless it has, had a good inline fuel filter?

i changed the fuel filter last night and the fuel that was coming out was almost black. i ran some sea foam in the tank and through the vacuum hose for the brake booster. it puffed a little white smoke, but nothing major. i will see how it runs this weekend after a few errands.