Roscoe91XJ

ok, so I fuel gauge isn't the most accurate so when the light came on I drove for about 4 more days. Then on my way home from work the engine started to sputter and loose power. I thought that I was just running out of fuel. Then I put some gas in it when I got home moved it and then the next morning it started up and then stalled and now it will not restart. I can here the fuel pump and have fuel pressure(no number it squirts out pretty good). I believe it is a spark issue. It almost sounded like it was missing but I checked the cap and rotor and it is clean. Haven't check plugs yet but I am leaning towards a cps. Any help would be great Thanks!!

tjwalker

Don't guess. Check your spark.

Remove a plug, keep it attached to the plug wire, place the plug electrode near a good engine ground. Have a buddy crank the engine while you watch. You are looking for a strong, blue, snapping spark. Yellow/orange/white indicates a weak spark, which may not be strong enough to start the engine.

If spark checks out, you must confirm actual fuel pressure at the fuel rail with a gauge. If you aren't at approximately 31, it isn't going to start. It is not impossible that running it nearly out of fuel either damaged the pump (fuel is what cools it) or you picked up "crap" from the bottom of the tank.

And if fuel pressure is good, confirm that the injectors are firing. A "noid light" is good for that. Pick one up at the parts store.

Good luck and let us know what you find. If you have NO spark, the #1 suspect is the crankshaft position sensor and the #2 suspect is the ignition coil.

Roscoe91XJ

Thanks a lot. I'll go check it out

Roscoe91XJ

ok so glad I checked has spark but not blue. So is it the coil? going to be checking fuel pressure shortly

cherokeeadam95

try sea foam? i had same problem tried sea foam... didnt fix anything let me know if it works for you

Roscoe91XJ

ok replaced coil and still nothing. haven't rechecked spark to see a color change yet.

Roscoe91XJ

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Roscoe91XJ

update: fuel pressure 41 and have spark but no starting still. Sounds like it wants to kind of jumps and then back to just cranking. So far replaced the coil and that's it. could it be the cps still or no?

Roscoe91XJ

also the spark is white still but is snappy. Just replaced the coil after it would not start because of the color of the spark. Am I looking at plugs wires and cap and rotor or is it something else.

Roscoe91XJ

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cherokeeadam95

i would start doing them one at a time, instead of all at once maybe its something like old, crappy wires or something. well..... is it possible to have great spark with a new coil, wires, rotor. but have a bad assembly causing it to reak havoc and not start?

Roscoe91XJ

FIXED!!!! After changing the ignition coil because of weak spark and no change in spark I then changed my aim to the CPS. No start after changing the CPS I then looked at the plugs again, they looked terrible so I change them out and what do you know after a few cranks it started right up and runs nicely again. So I think the root cause was the CPS which caused the jeep to miss fire and foul the plugs.

cherokeeadam95

congrats... i just cut my distributor hub nub off so i could fine tune the timing after it starts got it to run nicely also my coil is cracked in 2 places but still runs.... i poured water all over it and then tried to start it it was fine,, really got to check after its really hot after nice drive and if it has trouble hot starting it probably would be coil fyi so hope you didnt throw your coil away maybe u got a spare now . how is she running now?

Xjguy01newbie

Definitely a CPS. the cps controls the magnetic field to relay the starting of the engine.

Dave51

Actually, it's used by the PCM to determine injector sequence and ignition timing.