89 XJ 4.0 WONT START :-(

Yesturday it was running like crap, like it was outa fuel. So today after taking the GF to work, then getting back home, i go to start it to go to home depot and it wont light up :-(

I just bought a new coil, and still no spark...

Im new to the Jeep sceen and dont know that much about the 4.0l.

Two days ago it over heated and spewed hot water all over the engine, could this be a culperate?


thanx!

First thing I would check is the stupid CPS sensor and it's wiring harness. It's located on the driver's side bellhousing and you'll see the connector up by the fuel rail. Mine wouldn't start, I'd mess with the plug and it would be fine for awhile...finally just hacked off the plug and hardwired it.

sounds like the ever-classic crank position sensor

gawd dam that thing is a PITA to get to... we'll see... i hope thats it!!!

AH, THIS BOARD ROCKS! THE WHOLE PIRATE UBB ROCKS!

THANX GUYS!!!



Still intermittant stutters and sputters, could the sensor be dirty?

I unplugged it, tugged on the cable to see if it was the cable i was searching for, it was, and i pluged it back together and then giddy up it started!

still sputters :(

prob dirty from my over leakaged 4.0 valve cover, leakn like a byach

Change the CPS and if that don'e work check out the Fuel pump.

I just recently had to replace mine.

ok, so i cleaned the CPS, was covered in oil, no difference, still no spark... what prevents it from igniting? besides the nonoperation of the cps?


thanx!

PS Fuel pump works good! and i have pressure

On an '89 XJ (Renix) they used a 2 wire CPS. This is an analog sensor and can be checked with a DVOM. Unplug the sensor and attach the DVOM to the 2 wires on the sensor. Set the DVOM to VAC. Crank the engine and you should have at least .450 VAC. The minimum required for spark is .350 VAC. If this voltage is not to spec, I would recommend replacing the sensor. Before you replace the sensor, adjust your old one. Take a long bar and place it on the sensor bracket and smack it with a hammer, and re-check your voltage. This will bend the bracket closer to the flywheel. If you smack it too hard, the sensor will rub the flywheel and make a grinding noise. This adjustment procedure is to learn how to adjust your new sensor, and not a fix for your old one! You cannot get the voltage too high. The higher the better. Usually I get them around .800 VAC. during crank.

When you buy a new sensor from the dealer, tell them you want the updated kit with harness. This is cheaper than a sensor by itself. It also includes directions for by-passing the original harness and wires it directly to the pcm.

You might also want to check your MAP sensor and the vacuum hoses going to it. Mine went out at about the same time as my CPS and caused all sorts of problems. As soon as I got mine started, it just kept sputtering and then would die. It ran, but just barely. Sounds similar to your situation.

Anyway, the lower vacuum hose passes right over the CPS and the bellhousing, and it is not uncommon for both the harness on the CPS and the MAP vacuum hose to melt up against the host bellhousing. Good luck.

NEW CPS WORKS GREAT!

THANX YALL!!!