87xjDave

87 4.0 Liter 6cyl.

Yesterday the engine would crank but not start first thing in the morning. After about 9 tries cranking the engine just started normal. Drove the jeep all day starting and shutting off fine, no problems. This morning started fine, while driving felt like it occasionally it would bog down when trying to accelerate, almost like plugged exhaust. Recently had a problem where the catayltic converter was plugged and doing a similar thing but that has been fixed. Now I am not sure what might be causing this issue.
Has anyone had a similar experience with their 4.0 liter?

LizardRunner

test your injectors, that could be the cause of that sort of problem. Other thing to test would be fuel pressure/pump and possibly the filter

tjwalker

I always ask about the condition of tuneup hardware before looking into more complex possibilities. Failure to do so often results in the chasing of ones tail.

Plugs, plug wires, distributor cap, rotor, air filter, fuel filter.

87xjDave

I have replaced all the tuneup parts, cap, rotor, plugs, wires, fuel filter, and ignition coil. Fuel pump is running and there is fuel pressure in the fuel injector rail.
Whats strange now is the engine wont start and there is no spark from the coil & distributor.

tjwalker

For an 87, the #1 and #2 suspects for a no-spark condition are (in this order) a failing crankshaft position sensor and a failing (or bad contacts) on the ignition control module which is directly UNDER your ignition coil.

I would recommend testing of both of these and ensure the contacts aren't corroded on the ignition control module.

87xjDave

Thank you for the information.
I will test the CPS and on the ignition control module connections are you referring to the 2 spring type connections where the coil connects or the actual wire connections to the wiring harness?
When I replaced the coil I cleaned the 2 connectors where the coil connects with some sand paper the best I could.

tjwalker

Here is a link to a good thread that gets into details on testing the crank sensor.

http://www.jeepforum.com/forum/f11/c...ailing-639123/

I was referring to the ICM to coil connections that you already cleaned...........