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Crank but no start

GasguzzlinXJ

NAXJA Forum User
Location
Nampa, Idaho
2000 XJ, 4.0, 5 SPDR, 109k miles... has run very well ever since I bought it, recently replaced the head and ran even better since then, always started right up, never idled high or low, never stuttered or died. Go to start it one night, and it cranks but wont start. Has fuel to it, all fuses are good, have flipped around relays, etc. 5v going to and from CPS. Brand new spark plugs, coil rail seems to be in good shape. Interestingly enough, we gave it a shot of fuel starter in the intake, and it wanted to start just a little. Went to the store to buy some more, got back and tried again, giving plenty of fuel starter to it, then there was NOTHING seems like an intermittent electrical issue... I'm not great with electronics so any help would be appreciated. I'm leaning towards ECM malfunction? My radiator cap had blown off a couple times because of backpressure caused by a clogged reservoir line (resolved), and the ECM is right next to it.... please help!
 
Could be a lot of things at this point. You need to put it on a scanner and see what's happening.
 
ECM failure should only be considered after a complete and in-depth diagnostics and trouble shooting of the more common, more likely, and more logical causes for a no-start.

Test the CPS.
 
Is it getting spark? What about fuel injector pulse? That's my starting point.

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No check engine light. We plugged in an OBII reader and nothing came up. Wiped it clean in case the computer was in a loop. Spark plugs are ngk iridium but I highly doubt it has anything to do with the plugs. I'm gonna check the cps when I get home. I've heard mopar is the best way to go for a new CPS if that is the issue. Confirmation of this? Thanks guys
 
I've heard mopar is the best way to go for a new CPS if that is the issue. Confirmation of this?

Most auto parts stores sell cheap crappy Chinese made parts, some that even come with a "Lifetime Warranty". These parts are poorly manufactured and/or made from inferior materials. They are often out of specification, or even failed, right out of the box. The ones that are not faulty many times will have a short service life before they fail. Always buy top quality replacement parts and genuine Jeep engine sensors. Numerous threads detail long and frustrating searches for a "problem" that ended up being cured simply with genuine Jeep repair parts.

Cheap parts are cheap for a reason.
 
To check injector get a injector niod tester. They're cheap and that will point you in some kind of direction. Fuel,spark, and air make a boom...

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FIXED! So I read on some other forums that even though the CPS dont show signs of going bad, some guys still replace it and it fixes the problem. CPS tested out and everything else was good so I decided to give it a shot, and voila, the jeep fired right up like it hadn't missed a beat. Had the engine light on right afterwards which we cleared and now it's good to go. Thanks for the help guys!
 
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