Hi All, hoping someone can help me.. I have a 93 Jeep Grand Cherokee 4.0 (automatic). I have the infamous problem of the engine cranking, but does not start. After doing some research, last-night I ended up changing out the Crank Shaft Position sensor, Jeep still didn’t start. I verified I have fuel pressure in the rail ( 40psi) ( not sure if this is low)? I also have spark at my spark plugs. There is no engine codes, already checked. Shows #12 and #55
The battery in the Jeep was replaced last year, but I checked the voltage last night as I was packing up and it was 11v (battery a little depleted after me trying to start Jeep after 2-3 days).. Guess I need to charge it up.. I also tested the power input to the ignition coil and that was 10.5v…

So here’s my plan of attack, maybe someone has a better approach..

-Charge the battery
-Verify ignition coil is operating between 6,000 to 30,000 ohms and input power to coil is 12v
-Spray some starter fluid into the throttle body to see if the engine fires

Thanks for any help you can offer!

 

I think a little bit of starting fluid may tell you something. I would take out a couple or all of the plugs and clean and dry them good. Then put them in crank the engine a bit and check them to see if they are wet with fuel. They could be dry and that would lead to the injectors. Forty psi for fuel sounds about right IIRC.

Check your air filter make sure it is clean. Air is not usually a problem but you do need it for ignition.

 

good point about the spark plugs, they maybe wet.. I will preform these tasks and report back tomorrow.. thanks!

 

If you have no spark, check for a pulsing ground at the primary side of the coil. If you do not have a pulsing ground, you need a pick up coil/cam sensor. It is located under the distributor cap and just pops out.

 

So on my way home last night, I decided to just replace the ignition coil, even though I was getting 'spark' at the spark plugs.. It turned out that was the problem, once I replaced the coil, she started up just fine. I inspected the old coil, it has some cracks on the hard plastic\silicone body, not sure if I was loosing some power there.. Thanks for your help