I've got an 89 Cherokee Limited and I've been trying to get it running for the past 4 weeks or so.I've replace the crankshaft position sensorI've replaced the fuel pump replaced filter the oil pressure switch battery cables and starter spark plugs everything that I can think of and it still won't start I'm at a loss just trying to see if there's any other ideas

 

You need 4 things for it to run; fuel, spark, air and timing. If one of those doesn't happen, you know where to start.

 

Fuel pressure when cranking is about 39-38 and holds steady when not cranking. It has spark and air cause every now and then it'll run for bout 20 seconds then die. I've even replaced the distributor cap and rotor.

 

Shouldn't fuel pressure be in the mid 40's or better?

 

32 when running

 

When cranking itll be higher

 

it didn't get into the 40s until 94

 

Check to see if your fuel pump ballast resistor has power at both sides when running for that 20 seconds. Okay to bypass it also.

I would also perform my Tips 1,3,4, and 5 before losing too much hair over this.

 

If i could get to it in the time frame when it does start. Right now the starter turns over but not the engine which means something else is wrong.

 

Any other helpful ideas?

 

Starter cranks but engine doesn't? Like the starter isn't engaging anything?

 

Sounds like it but every now and again it cranks

 

That sounds like bad solenoid on the starter.

 

Or chewed up teeth on the flywheel. But that's much more doubtful. I know you said you just replaced the starter but I've put in "new" starters from autozone, etc, and they've been faulty out of the box.

 

It was a refurbished starter from oriellys. Lol