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Replaced CPS...still no start

9

90xj4x4

NAXJA Forum User
Location
Simi Valley,Ca
Hey guys. Ok I searched but couldnt find what I needed. My XJ died a few weeks ago. Had been driving it all day and shut it down...then it wouldnt start. I parked it and the next day I tried to start it. Same situation, cranks like normal but wont catch, not even a sputter. Today I dove into it. I figured it was the CPS so I replaced it. Still nothing. Have spark, fuel, and compression. I repaced the spark plugs b/c they were wet with fuel. Still nothing. Is there a fuse that could be bad somewhere?? Cap rotor and wires are 15k miles old.

PLEASE HELP!!!!

BTW: 1990 XJ 4.0 AW4 NP231 Stock motor w/ Optima battery
 
Maybe the engine harness crapped out? My '88 limited did the same thing, turned out that the ecu to everything else harness had broken down over the years. I recall a lot of people saying that the Renix harnesses are good for break-downs. And no, the harness from a manual tranny XJ won't work if yours is atuo. It is missing some plugs, and vice-versa.
 
The rig only has 138k miles and has been meticulously cared for. Could the harness have gone out already? I have spark so im guessing that probably isnt the problem??
 
is there any smoke from the exhaust while you try to start it? Did you look at the fuse for the ECM?
 
not sure I think under the hood, give me a min I will run out and look at mine. if there is no smoke there is a major piece of the puzzle missing somewhere. You said the plugs are coated with fuel?....was there so much that it leaked out when the plug was removed?...
 
no not that much fuel. just enough that the plugs were wet and they stunk. I poured a little bit in the throttle body to help start thinking that an injector was clogged. I had been cranking off and on for like an hour so there was alot of fuel in there. there is pressure at the schrader valve on the fuel rail and the injectors were replaced like 40k miles ago.
 
ok, it may sound stupid, but is it automatic or manual? There is a fuse in the fuse box under the hood for the CPS, although It highly unlikely that this is the problem, check it...seems to me if you have some spark and by the sounds plenty of fuel, you should at least hear a popping noise when trying to start..
 
really? what model is yours?..I may have misread your post....if I were you, I would check the timing,... I mean you said you were driving and all of a sudden it stopped running one day... sounds like it jumped time to me, but you should still have some detonation (popping) or at least some exhaust smoke. Be careful from this point on, until you pin point the problem, if it did jump time you could slam a piston or throw a rod.
 
After looking at some of the manuals in the shop I would bet money it jumped time. I replaced the timing chain on one for a customer a few weeks ago and his was stretched wearing thin because of stretching and constantly rubbing the block. How many miles are on it? The chain usually lasts for a long time, but occasionally they do break or the sprocket will shear...
 
It only has 138k miles and has been meticulously taken care of. If it were the chain wouldnt there be some signs of it going bad? like running crappy or smoking. It doesnt catch or sputter or anything. just cranks away. It is a 1990 Limited. Where would the underhood fuse box be located?
 
well to be honest, it seems there would have been a little rough idling, or some popping sounds while idling but to be honest I would put anything past a jeep anymore. Have someone turn it over while you lie under the front and listen near the timing cover? SOMETIMES you can hear a slight rattle or clicking if the chain broke, or charge the batery really good and have someone turn it over while you use a timing light, I don't know if your model has the timing marks on the front of the balancer, you may be able to check it with the distributor, I'll check for you in a sec. The fusebox on mine is on the passenger side under the hood, but mine is a 98. I'm just a redneck mechanic from Georgia (lol), but sounds like a timing problem...be back with you in a sec
 
http://www.sierrajeep.com/timing.htm look there for some timing tips, I don't know if you have ever dealt with timing but heres a simple way to eliminate it as a problem. On the front of the harmonic balancer there are some timing marks and number, there is a little tab on the block (like an arrow) using a ratchet and socket (or your hand if you eat all your wheaties) on the center of the balancer turn it so that the number 0 lines up with the tab (or arrow) on the block, remove the valve cover (very easy) and look at the valves. Piston #1 should be at TDC (Top dead center) if all the valves are open, or all closed or if they are all distorted then you have a timing problem.

I still believe you have a timing issue, just fits all the problems
 
or easier just take the valve cover off and turn the balancer if the valves raise and close your chain is on the gear
 
Have you messed with the distributor or timing chain lately? How much compression are you getting? If there is fuel, compression and adequate spark something should happen! Double check your spark intensity! I've dealt with rigs that sparked with a pinkish color and would not fire at all. The coil or related components could be bad. Good luck!
 
Thats very true, but you said you were getting fire... it should be bluish, sometimes even bright white. if you checked the fuel, then you got juice...if you've got fire on the plugs you've got ass to light it,....the only thing I can imagine is no rotation of the valve train, (timing chain)
 
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