Recently noticed my 89 Cherokee Laredo with L6 engine is getting hard to start after the engine has warmed up. So far I've managed to get it started with continuous cranking, but it's obvious something is causing the hard startup. I've checked the ignition and the plugs are getting its required high voltage, so I'm guessing the problem is fuel related.

I'm concerned the starter itself could burn out with the excessive cranking. Anyone have any suggestions on what could be the cause of the problem? I'd appreeciate any comments/suggestions.

 

Make sure that you have a good bright blue spark. Also make sure that you have the correct fuel pressure. Your year should have 39psi +or- 5psi. You can rent the pressure gauge needed at just about any parts store. Connect it to the fuel rail to make sure for the proper pressure. This would be the best place to start.

 

I had the same problem on the 94 that I bought 2-3 weeks ago. I cleaned the TB and IAC, put in a new CPS, checked fuel pressure, and nothing helped until I put in a new set of spark plugs and now it runs great and starts every time.

I should have started with the simple do anyways stuff but was stubborn as my son told me to do that when he drove it home for me after I bought it.

 

Begin by clicking on the link in my signature and do tips 1,3,4, and 5 before chasing your tail.

 

hard starts can be lots of things (coils, plugs, plug wires, starter, not enough volts during cranking, sensors, etc.). But as cruiser54 stated, do the things in his signature first.

 

Thanks for the feedback. I did check the spark with a spark tester and it showed a good spark. I assume the CPS is good since (I think) I read somewhere that if it is bad then one doesn't get a spark. My next thought was to check the fuel pressure with a guage I bought some time ago. Knowing what pressure to look for is very helpful.

I'll check Cruiser's link today.

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Just do them. Super critical. There is a test for the CPS also (post 7), but do the basics first.

Plugs (NGK), wires, cap and rotor, should just be replaced.

Throttle body and IAC cleaned (Post 11).

Check and make sure the intake manifolds bolts are not loose and the engine vacuum harnesses are not messed up.

Keep in mind that a Renix Jeep will NEVER light off on the first revolution by design. It's usually a few seconds of turning before the ECU fires the injectors.

 

They do that to make sure to prime the cylinders?

 

No. It gets spark BEFORE fuel or you could have huge backfires if it were the other way around. Don't know why it's that way, but it is.
It can be minimized by doing Tips 1 through 5 in my link below. Post 7 can help also if the CPS voltage output is low.