I have a 96 cherokee 4.0 h.o. It currently will not start. Ive changed the crankshaft position sensor and the ignition coil. I have also checked all fuses and relays. It will crank but wont start. The fuel pump relay and asd do not switch on unless i take a wire from the negative battery and connect it to the dark blue/yellow wire on the relays themselves under neath the pdc. Any thoughts on what could be causing this? Also the is no power to the ignition coil unless i have that wire hooked up.

 

Sounds like an issue in the ignition switch to me...

 

None of those things get power unless the engine is cranking or running. The relays are controlled by the computer which shuts off the fuel pump if it does not detect that the engine is spinning. This keeps the fuel from pumping all over the ground after you crash. To actually test that you need someone to crank the engine while you check voltages. I believe the coil is similar in that the computer will shut it of unless the engine is actually cranking.

 

Have you checked to see if the spark plugs are sparking? Do you know for a fact whether it is getting fuel?

 

It only gets fuel when i hook the wire up. Other than that the pump doesnt run. And last i checked there was no spark.

 

Also what do you mean when you say something is wrong with the ignition switch?

 

Ok so i changed the ignition switch and still nothing. Any other thoughts? Still no fuel and no spark. Need to get this running soon.

 

Check out that the distributor is in good shape?

 

Seems to be, but im getting no spark even before the distributor.

 

Is your ASD relay clicking on when you try to start the motor?

 

No the asd doesnt click on when i try to start it

 

Hmm. The ECU grounds the ASD so the engine can start and run. Next thing i'd check is whether the ECU has power and ground. Plugging a scanner in and seeing if it responds might be a useful check.

 

Well i tried putting a obd 2 on it and it wont link. Is that what you were talking about?

 

Yup. There is a ECU (PCM, JTEC, whatever they called it in 96, lol) problem then, perhaps no power, bad ground, blown fuse, dirty/corroded connectors?

 

Ive checked all of the fuses those are good. I know that theres a bolt.missing to hold it onto the inner fender. But how would i check the grounds on it?