We have replaced all the spark plugs in our 1991 jeep cherokee but dont have the diagram of what plug wire goes where. Can you help me?

Just follow the pattern as it is under the hood. If you have to, draw a diagram to help you along the way.

Turn the engine to TDC, so the line on the crankshaft balancer lines up with the zero. (Number one cylinder all the way up, and it should be blowing air with your finger in the spark plug hole on it's way up. This is TDC) Note, make sure you turn it the same direction as when it is running!!!! (Turn it with a socket on the end of the crankshaft, clockwise facing the front of the vehicle) Now with the distributor cap off, the rotor should be pointed at where the number one spark plug wire goes into the cap.

spark is triggered by the crank sensor and the cam sensor inside the distributor. but the actual signal to the coil comes from the computer. If I remember correctly the hot side of the coil runs to the back of the alternator. I am sending along a complete wiring diagram for your vehicle but I suggest you get a haynes or chiltons manual for test procedures. Don't follow their wiring diagrams or you will get side tracked to death trying to figure them out (inaccurate is a mild word)
http://www.scribd.com/doc/18999822/Jeep-Wiring-2
Since I can't do the testing from here, I;m trying to give you the best possible means and chance to figure this out. Any questions just ask!!

Review the Jeep ZJ Repair Manual in the Firing Order (page 10 and 11) for 4.0L 6-cyl and 5.2L 8-cyl.

I really hope hepled with this (remember rated this help) Good luck.

what year and make of vehicle and what size engine?

I got 96 and more then half the time its always the pumps on jeeps

Review this information:
- ZJ-Secc-14-Fuel-System
- ZJ-Secc-8W-Wiring-Diagrams

Good luck... and dont forgetted rate me!!!

Ill send you a diagram. What engine do you Have?

For a 4 the firing order is 1234 front to back and the distributor fires clockwise. Find one and run wires from there.

For a 6 its 123456 front to back and is also clockwise.

Joel

the spark plug at the front of the engine (nearest the grill) is #1 on both the 4cylinder and 4.0 in line six cylinder.