Bare with me. First because I'm a girl and this is my first jeep and secondly because this is number two jeep sitting dead in the the garage.

My jeep is fuel injected and started sputtering backfiring and just general misbehaving. We replaced the O2 sensor and that seemed to clear that up. However I wouldn't know because I haven't been able to drive it much.

We also found a wire that was shorting out under the dash. When you'd move this wire the jeep would shut off. Almost like someone turned it off. We replaced the patch of the wire that was rubbed and shorting out.

Now I have no power going to the fuel pump. The jeep turns over fine but when you turn the key on you cannot hear the pump start up. We checked the power coming into the pump, no power. If you jump the fuel pump, where the relays plug in the pump comes on. Ok, replaced the relays. Still no power to the pump.

My husband being a drama queen bought a whole new computer. I put it in today, still no power to the fuel pump. I didn't think it was the computer anyway since you can jump it and the pump comes on.

I know it has a crank shaft position sensor. However my husband isn't talking to me (sigh) and says I can fix it myself. (we are racing to see who can get their jeep running first. He has a 90 yj which seems to have the same issue.)

So are there other sensors or or fuses I should replace. I know there's no real way to check a sensor.

I just don't understand why fixing a short would cause it not to run.

Oh, one more thing. The reason we went looking for a short was because the amps were running very hi 18 or so. But fixing the short did not bring the amps down and then the pump just stopped coming on.

I'd put a new alternator on it and pulled it and had it checked, it's good.

Thanks in advance.

One more thing. The fuel gauge works but hubby says there's no power getting to the fuel pump. I think he's trying to sabotage me.

you guys need counseling

no power to the pump would not disable the guage, as it works by impedence (i beleive).

im (still) waiting on my replacement fuel pump, but when i was troubleshooting mine, at one point i had no juice going to it. it turns out it was becasue the battery was pretty weak.

after you replaced the relays, did you have juice coming out from there? if so, check the wire between the relay and the fuel pump. if no, check the wiring between the relay and the ecu.

i don't think (i could be wrong) that the crank position sensor has any bearing to your fuel pump, but i could definitely be wrong.

Found a place online that told me how to check the trottle posistion sensor. It checked out fine.

Some guy at the dealership told me that if the ECU doesn't get a signal from the CPS that it will shut down the fuel pump. Can anyone confirm this? We did drop the tranny a few weeks ago to replace the slave cylinder. But after that it ran fine.

And thanks for the advice on counseling. But that won't stop hubby from stealing parts off my jeep!

he needs a good

I just had a very similar problem (no power to fuel pump) and I tried a lot things. It turned out to be one of the relays under the hood in the power box. I tried the fuel pump relay in the beginning and did not have any luck, but on a whim replaced the auto shut off/auto shut down relay and the fuel pump kicked right on. Cost me $6 and a few hours of frustration, but it beat dropping the gas tank.

I replaced all the relays.

I have power coming into the ecu and going out. I completely bypassed the ignition on the column with an under the dash switch.

Still the fuel pump does not come on, does not prime, no fuel pressure or weak pressure. I have no spark either. So even if I jump the fuel pump to get it on, it still does not start. Also replaced the crankshaft position sensor. Now I feel like I'm just throwing parts at it.

What could be telling the ECU to not start the fuel pump and to not spark? The only sensor left would be the throttle position sensor but I checked it with a multimeter and it seems to be fine.

Thanks, any help is appreciated. We were supposed to be taking the jeep for an off island trip on the 20th and if I can't make any progress by Tuesday, I guess I'll just have to take it to someone and get ripped off. Already threw $300 at it.

I am having similar issues. I tore that whole wire harness appart, I even took out the ECU Opened it to see if there were any issues with it, Water damage, Burned or shorted out circuits. I read on another Thread that it was the Shut down relay next to the battery. I am going to replace both of those relays today to see if that works.

One note that when the Vehicle finally runs. and it warms up it has no problems restarting. Its only when I try it when it is cold. "Mornings"

I don't really have cold mornings in Hawaii. My ECU appeared to have cracks in the plastic interior and there was water in the plug. On important note; The jeep ran before we cleaned out the ECU plug. After cleaning the water and mud out of the plug is when we got no more spark and no fuel pump coming on.

The reason we were messing with all this to begin with is because my volts were running high. The dash gauge was pegged out and 19 volts. Thinking that we had a short somewhere after fixing the one short under the dash is what led us to cleaning the plug.

Maybe jeeps only run with water and mud in all their connections?

The jeep is FIXED!

Ugh the problem was so stupid, simple and cheap.

We tested the pink wire with a yellow stripe for power coming into the ECU. Yes power was coming in but no power was coming out of the ECU. Which orginally led use to believe the ECU was bad. But we eliminated that as an issue with a new ECU.

On a whime this morning we hooked up the computer to the ECU. It said no power. Hmm power was going in. So then we popped the big plug off the ECU and again checked the line with power coming in but this time checked them for continuity between the wire and the out going inside part of the plug. One had no continuity.

Took the plug apart and sure enough the power wire was broken. Soldered it back together, hooked it all up and turned the key on. Instantly the fuel pump primed and it fired right up.

I'm glad we only threw $300 at it. We were almost ready to take it to someone else.

I hope this helps someone. After searching online for three days, it's really annoying when no one explains how or if they fixed it.

Oh and I couldn't have done it without hubby. ♥

Can you tell me where you found the broken wire at? and what number was the wire you fixed if you happen to know.
Thanks for the help.

We found the wire broken inside the rubber plug to the ECU. On my 90 YJ there were only 2 wires supplying power into the ECU. The broken one was the smaller gauge wire. I never found a diagram of the plug itself.