Jeep Wrangler Forum banner

Turning over but no spark

2K views 4 replies 5 participants last post by  CMike357 
#1 ·
Here is my problem: Daughter was driving, when turning after being stop at traffic light jeep died. I went to check on it and when I hit the key I just got hard clunk. Starter was engaging flywheel but not turning engine over. This was late at night so I towed it 3 miles home with my 86 jeep. Waited until the next morning and tried the starter again same result. I assume something is frozen in engine so I removed the spark plugs and manually turned the crank with wrench ....good news it was turning freely. I then also turned it over with key no issue. Reinstalled spark plugs and tried to start it but now it is turning over but doesn't seem to be get any spark. I checked spark with a device that connects between the plug wire and the plug. No spark......any ideas?
 
#2 ·
Lots of ideas, none of them good.
First thing that comes to mind is a jumped tooth on the timing chain.
Hopefully it is only a dead coil.
Basic diagnostics should get you headed in the right direction.
Pull plugs and determine compression stroke of #1 cylinder. Pull distributor cap and see if rotor is pointing to #1 spark plug wire.
While you have spark plugs out, do a compression test to check for a bent valve. I have heard that a 4.2 is a "non-interference engine" but you don't state what engine you have.
If your rotor is pointed at #1 plug wire post for further suggestions.
Good Luck, L.M.
 
#3 ·
Hi, even if it did jump time it will still fire just not at the right time, so this should not be what is wrong. I would think it is the ICM or a bad coil or in the distributor pick ups, you just have to test them all.
 
#4 ·
With a 95 YJ the 1st thing I would check is the CPS (crank position sensor) If it doesn't send a signal to the ECM then the ECM doesn't send a signal to the coil to send spark.

The CPS is located on the drivers side top portion of the bell housing. You can test it with a simple test light. Turn the key on and find which of the wires has power in it, then move test light to the other wire and turn key to start, if the test light flashes as motor is rolling, the CPS is good if it doesn't the CPS is easily replaceable.

If it isn't the CPS, the next in line would be to replace the coil.

As far as what caused the "clunk" and refusal to roll over that night...Possibly the motor was vapor locked when it stalled, from trying to start out in too high of a gear? and when you took out all of the plugs, you released the vapor. It is possible that it jumped time, but unlikely since you said that it was rolling freely by hand.
 
#5 ·
Well, since no one has suggested it, have you checked to see if it is throwing any codes? Might help you track down the cause. Let us know what you find.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top