79JeepinCJ7

Hey guys, I've been helping a buddy with his 2000 chorokee. 4.0 aw4 auto. He drove it into his shop. Installed a 6.5" IRO lift and went to start it back up and nothing.

When he turns the key to the ON position he gets dash lights etc but now his fuel gauge stays at E (has fuel in it) and it worked before the build. Also the fuel pump wont kick on.

If you turn the key to START nothing happens. No click nothing. If he dumps gas down the tb and jumps the starter it will start until it runs out of the dumped gas.

He has taken the fuel pump out and jumped it to the battery and it turns on so the pump still works and also checked all the fuses and relays everywhere.

He replaced the ignition switch on the column. The NSS is bypassed and has been for a while before he drove it in but he checked that again and it is fine.

The computer was not unplugged when he was welding but the battery was.

So idk if he is fighting 2 things at once here but it seams that the fuel sending unit/pump is not working.. and it wont start at the key. Does the computer control if the jeep will crank or not? Could the ecm have gone bad making this all the same issue?

Thoughts? Maybe some more steps to take? He is getting power on one of the wires back at the fuel pump. But I dont have a wiring diagram of the fuel pump sending unit etc to have him show me/tell me which one.

I imagine it always has power with the key on and the computer just completes the ground circuit to turn the pump on? But then why would the guage have stopped working also?

Kind of stumped here but this is also my first cherokee/4.0 setup ive worked on so some guidence would be much appreciated!

79JeepinCJ7

Bump... Noone?

79JeepinCJ7

Bump Again, still no luck yet.

DieselD

Is there fuel pressure at the rail at all?

Have you tested the battery?

CoffeeCommando

I would generally say if jumping the starter works then the starter solenoid might need to be replaced, but that's just to start it. You said it cuts off after that and you also said the fuel pump works when jumped as well. Since you jumped both and it started, and the only job the starter does is to START it (which it IS doing) then you need to open up a wiring diagram and investigate the fuel pump.

Also, I think there is a fuel pump cut-off switch somewhere in that circuit. Make sure that wasn't accidentally flipped off some how. I don't know where it is but I'm sure if you google it or look in a book you'll probably find it.

The only time I ever had no sound whatsoever from my XJ when trying to start it was when my starter died after a weekend of offroading out at a beach when it was low tide and we got caught in high-tide before we finally left. The started "tested good" (which is to say it's electrically operating, but not under a heavy load like it is when it's re-installed in your transmission). I bought a new starter and it immediately started after that.

Your friend wasn't going through lots of salty water before he got his lift-on was he?

79JeepinCJ7

You can make the engine turn over by jumping the starter but that does not make the fuel pump work. It only starts by dumping fuel down the throttle body.

There is 0 fuel pressure.. the pump isnt even turning on. No fuel gauges nothing. But if you take the pump out and test it, it turns on.. so besides the computer does anything else control the pump or wouldnt let it turn on? Ignition switch is new also.

The fuel shut off is a relay and we changed them all.

Parsnip

Asd relay? Did the jeep get bumped on real good during install maybe? I know on my buddy's 97 we hit a bump a little too hard and it tripped the relay

Marley'sCherokee

This might help you

http://www.jeepforum.com/forum/f11/c...-relay-993675/

JeepsMyName

I know on my old 89 the oil pressure sending unit went bad and caused the fuel pump not to kick on.. just a thought I know there is alot of years inbetween so they might have changed that

79JeepinCJ7

We checked and changed the ASD relay. However the ASD relay wont stop the jeep from cranking over the engine when you turn the key to the start possition. This has nothing at all when you turn the key to start.

Jeepsmyname, i'll look into that but being an 89 it was a Renix system so it was a completely different animal but thanks!

Parsnip

True it woukdnt stop it from cranking over...but fuel and spark delivery woukdnt be there if it was bad/out...what about the ignition lock cylinder on the column?

CCKen

Here's a layout of the fuses in the '00-'01 PDC.



Here's a layout of the fuses in the JB. Fuse 19 is the starter relay control coil power.

79JeepinCJ7

He changed the ignition switch but not the lock cylinder.. that doesnt actually do anything but allow you to unlock the wheel. The rod that runs along the column and pushes the switch is fine. The radio etc turns on so its getting power to the dash etc.

Thanks! He took a test light and checked every single fuse already and replaced the solenoids/relays.