stumptownxj

Hey guys,

I've got a '95 XJ sport and I recently went to hop in it and the engine won't start. It is turning over but then nothing more happens.

Do you all know some good places to begin looking or some common starting issues with the 4.0L 6cyl engine?

Any help is much appreciated.

-stumptownxj

ZINGGG

Battery, Crankshaft Position Sensor, fuel pump, spark plugs, ignition coil, etc etc. The list goes on.

You should do some testing before throwing parts at it. You need fuel, spark and air.

One of the most common causes of a no start in the Jeep 4.0 is the crankshaft position sensor though.

tjwalker

Job #1 for any no start is to determine what part of the equation you're missing. We'll assume it has been running recently so let's leave compression out of that equation. That leaves spark and fuel.

Remove a spark plug. Keep it attached to the plug wire. Place the electrode of the plug near a good engine ground. Have a buddy crank the engine while you watch. You need a strong, BLUE, snapping spark. Yellow/orange/white indicates a weak spark which may not be strong enough to start the engine. #1 suspect for weak spark is the ignition coil. For no spark, the primary suspects are the crankshaft position sensor and the ignition coil, in that order.

If spark is good (and ONLY if), then verify fuel pressure. For a 95, you will need approximately 31 psi to fire it up. Use a fuel pressure gauge. Or try a shot of starting fluid or a very small amount of gas into the intake. If the engine starts and runs for a few seconds with this technique, then you have verified a FUEL DELIVERY problem.

Good luck, use a testing based strategy to figure out what the root cause is. Keep us updated!

stumptownxj

Thanks Guys,

A friend and i went to look at it and i was about to start testing the plugs when it just started up.

I'm not sure what happened or why it started but i didn't even have to bust out my wrenches, I am going to have my mechanic take a look and see if there is a problem that will come back to haunt me in the future, but for now i have my jeep back!

Thanks again,
stumptownxj

stumptownxj

Surprise suprise... No start

This time I did bust out some wrenches and found there is no spark coming from the ignition coil, so we tested it and the coil checks out.
There is also fuel getting to the injectors, and since the problem was intermittent, we figured electrical.

My next step is to switch out the cps, but I don't know of it is an OBD II or I. On my 95 sport, which would it be?

bighouts5591

I just had this problem with my 95, it ended up being my o2 sensor wires were burned through and laying on the exhaust manifold. The short blew the fuse, which also happens to have the fuel pump and injectors on it. Fixed the wires and put in a new fuse and she runs like a champ

Radi

95 should be OBD I. II's have a diagnostic port under the driver's side knee panel and the ECU mounted on an aluminum heatsink.
Get the OEM part from a Jeep/Chrysler dealer. A fair number of the aftermarket parts are either DOA upon installation, or at some point shortly thereafter.
If you absolutely HAVE to go aftermarket, get the NAPA sensor.

F1Addict

Radi is referring to the CPS.

stumptownxj

I Replaced the crankshaft position sensor (after a considerable amount of stretching and squirming to get the bolts off) and she started right up!

Thanks do much for the help. I'm stoked it was only $80 and I didn't have to tow her.

Radi

Yes. Thank you for clarifying, I should've specified.

Stumptown- awesome! Glad you got 'er running!

Sara Lou

It's the Factory security system