Crank Dammit!

I have a 90' XJ that isn't getting fire to the engine. I thought it was the ignition coil but I was wrong. All it will do is turn the starter. what would be my next guess? I know it's hard to diagnose on the internet but what would you check next?

Check and clean your all eletrical connections AND grounds under the hood . I would say it is most likely to be the CPS or the wiring harness that connects to the CPS .

tap on the starter relay with something.. its under the relay cover on the passenger side of the engine. and of course check the crank position sensor at the back drivers side. the connector can be bad sometimes, and the sensor too. also, check for fuel pressure. press the valve core in on the fuel rail to see if any fuel sprays out under pressure. and check for spark....

ok, here is the easy way to troubleshoot. get a can of starter fluid or brake cleaner. have someone crank the engine and at the same time spray some into the intake. if she fires up, then you have a fuel problem. if she doesn't then you have an ignition problem. ignition= check starter relay, cps, coil, etc....
fuel=check pump operation, fuel filter, etc....

Back probe the crank sensor and the cam sensor to see if it is reading them. That was the problem on mine i did everything but check those 2 sensors and it was the crank then a week later the cam. There are three wires on each sensor, a ground, voltage, and reference. Your looking for about a 3 volt pulse on the reference wire if you have the means to test them. I got my colors from alldata but don't remember them.

oh man this is so close to the problem im having on my 89 xj. but now i also got me a dead new battery to boot!! im takin the battery back (replacement). & the new MAP censor too (that way i can afford a new cps).

Sounds like the crankshaft position sensor(CPS) to me. Unplug the sensor and clean it and replug it back in and see if you can get it to crank. Are you getting fire out of the coil? If not, I am willing to bet it is the CPS.

reloader said:

I have a 90' XJ that isn't getting fire to the engine. I thought it was the ignition coil but I was wrong. All it will do is turn the starter. what would be my next guess? I know it's hard to diagnose on the internet but what would you check next?

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You said all it will do is turn the starter? So the engine is spinning over? or the starter spins and it wont engage the flywheel? If the engine is spinning but wont start, check for spark. Pull a plug wire off and put a screwdriver or something in the boot and hold it about 1/2 an inch or so from the block. It should jump a blue spark to the block. Don't get knocked on your ass. If it sparks pull a plug and see if its wet or dry. If it wont spark at the plug pull the coil wire off the distributor and hold it near the block and crank it over. It should be throwing blue lightning even faster. If the plugs are dry and it has spark at the plug, hit it with very little starting fluid or a little gas in the throttle body. Like a thimble full. Your just trying to prove if it is getting fuel or not.

Hey, thanks to everybody. I'm gonna check the CPS, I feel kinda stupid cause I didn't check for a spark. I just saw it wasn't gonna crank so I started throwin' parts at it.

UUUUMMM, I'm not being a jackass, but you keep confusing me. You say it wasn't gonna crank. I take that to mean that the starter, battery or related parts would not spin the engine over. To not fire would mean that its cranking over but not starting. Again I'm not picking on you. I'm trying to make it easy for you to tell folks whats happening with your stuff. Plenty of good people in here to help you out.

reloader, if yours is doin the same as mine is. you have spark, fuel & compression. but it just isnt "catching" to run/start. right? are you getting the "popping" noise when you're cranking it? sounds like its trying to catch & start?


let us know how you're doing with it.

Hey, yeah I do mean that it is cranking over but not starting. I pulled my distributer wire off and I'm not getting a spark. I'm gonna try to check the CPS today, but I gotta wait for it to warm up a little.:shiver: I'll try to keep everybody posted on my progress so maybe it will help somebody who is having the same problem. I bought this thing for $250. the guy I bought it from had never cranked it and the guy he got it from was an idiot because there is all kind of stupid shit done to it. I'm kinda worried that it could be a computer problem because the dash is off and somebody has been messin with it.