98 TJ won't start

888rt · Post by **888rt** » Fri Jul 01, 2016 2:25 pm

About a week ago my tj stopped working. One day it started and the next day nothing. There was no fuel pressure in the rail so we bypassed the relay and found that the fuel pump still works fine and the relay is fine. After testing all the fuses and diagnosing we tracked it down to the ignition pickup sensor and/or the crankshaft position sensor. Yesterday I replaced the ignition pickup sensor and it didn't work so today I replaced the crankshaft position sensor. The car started up, and then immediately shut off. One thing that did change is that now the fuel gauge turns on but it still cranks, doesn't start and still has no fuel pressure. Any idea of where to go from here? Any help is appreciated. Thanks.

243 · Post by **243** » Fri Jul 01, 2016 2:56 pm

'888

This forum is full of smart folks but mostly FSJ owners, I would suggest registering with Jeepforum, they have a very active TJ forum.

Nikkormat · Post by **Nikkormat** » Fri Jul 01, 2016 3:01 pm

I've been helping fix this one. Also worth mentioning that his obd port is dead. Haven't backprobed to see if it has power yet.

He's on a few other forums but hasn't gotten any replies to his post. He knows how active members of this form can be and thought he'd pick your brains.

243 · Post by **243** » Fri Jul 01, 2016 7:13 pm

I am not saying go away, wish I could help but my knowledge stops with CJ/YJ''s.

Curly · Post by **Curly** » Fri Jul 01, 2016 7:21 pm

If the check engine light doesn't come on with the key, the pcm is not awake. Fuses, wiring should be checked, but it sounds like a problem in the 5 volts reference circuit. That includes the tps, map, ect, oil psi, ckp, cmp. Try unplugging each sensor 1 at a time to see if the check engine light comes back on. If it does, that sensor is shorted. Common with the ckp.

Curly

Nikkormat · Post by **Nikkormat** » Sat Jul 02, 2016 8:04 am

His distributor pickup was shorted so that would make sense.

csuengr · Post by **csuengr** » Sat Jul 02, 2016 12:52 pm

Also make sure there is 12V battery power on pin 16 of the OBD plug.

Go top the fuse center and check the PCM fuse AND relay. Pull the relays out and plug them back in.

888rt · Post by **888rt** » Sun Jul 03, 2016 2:40 pm

After tearing apart the ECU to try and see if the capacitors were dead and then reassembling it, the OBD started working again yet there are still no error codes.

Curly · Post by **Curly** » Sun Jul 03, 2016 5:11 pm

Is the check engine light coming on with the key? If not, the jeep will not start. See my post above.

Nikkormat · Post by **Nikkormat** » Sun Jul 03, 2016 6:09 pm

Sweet the OBD Works!

We'll check the 5v rail on Tuesday.

888rt · Post by **888rt** » Tue Jul 05, 2016 6:28 pm

Thanks to everyone for their suggestions. I checked the 5v reference circuit and everything checked out fine. The issue was the fuel pump fuse. When we were originally diagnosing the problem, we checked all the fuses first and then while diagnosing with the multi meter the battery sparked and at the time I thought nothing of it. We then found the issue was the camshaft position sensor and I replaced it. We also had managed to kill the fuel pump fuse so rechecking the fuses today allowed us to fix our problem.

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98 TJ won't start

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