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Unread 11-05-2009, 09:54 AM   #1
sixone
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Join Date: Nov 2009
Location: Bucharest, Romania
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4.0 94 ZJ crank but won't start

tried to start the car today but the engine does not fire at all..
after some check-ups i got to the conclusion that the gas is coming, it has sparks but won't fire..
so what i've tested so far was:
fuel pump - when i turn the key i can hear a noise from the back
fuel pump relay - is sending 12v
i've pressed the fuel gauge on the ramp with a screwdriver (while somebody else was cranking the engine) and gas was flowing out..
i removed all the spark plugs, 3 (2,3,4 cylinders) of 6 were very wet (gas) and the rest of them not as wet as the others (i don't know why)
after i clean them, tried to crank the engine with one spark plug out and got a beautiful spark.. i put them back but no luck..

i'm lost.. i got gas and spark but it won't start.. i've read something about the crank sensor.. but i'm a little bit confused, if i have a good spark, could it be sensor?

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Unread 11-05-2009, 09:59 AM   #2
mhems001
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1993 ZJ 
 
Join Date: Apr 2009
Location: Chesapeake, VA
Posts: 31
have you tried drying them out and crankin again? or have you checked your throttle body and IAC to see if they are clean and working?
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Unread 11-05-2009, 10:19 AM   #3
sixone
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yes, i cleaned the spark plugs with a dry cloth, brush and even with a lighter.. but the car didn't started..
tried this twice, because after i put them back and run some more tests they got wet again..
throttle body looks okay, more than that i sprayed some starting fluid directly on the throttle body, again with no luck..
i don't know where the IAC sensor is, didn't checked that..
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Unread 11-05-2009, 10:29 AM   #4
jeep210
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1997 ZJ 
 
Join Date: Oct 2009
Location: East Texas
Posts: 192
It is not the CPS because you do have a spark. You have a spark plug issue or a fuel issue. Test each plug with its own wire and see what kind of spark you have. If they all look good, then you have to look at fuel.

It sounds like you are getting too much fuel. But, it could be that the plugs are not firing and they get wet.
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Unread 11-05-2009, 10:58 AM   #5
sixone
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well.. cleaned the throttle body and iac valve meanwhile, but as i expected still no result.. i tested 2 plugs (after i clean them) and the spark look good.. the plugs don't look very good, they seem a little bit worn out.
the weird part, what i don't understand, if the plugs are faulty why the sudden problem? until today the car started very good.
i will try to change all the spark plugs tomorrow and see what happens..
too much fuel means high pressure on the injector rail? is there any other way of testing the pressure than using a gauge on that valve?

what i also tried few mins ago: take off the fuse and fuel pump relay and sprayed some of that starting fluid directly on the throttle body with the throttle opened. i'm not sure if this supposed to start the car for a few seconds, but nothing happened..
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Unread 11-05-2009, 11:08 AM   #6
jeep210
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1997 ZJ 
 
Join Date: Oct 2009
Location: East Texas
Posts: 192
Best to use a pressure gauge to see if you have normal pressure. Autozone may provide a free use gauge. You leave a deposit for the gauge and you get it back when you return. Ask about the free rental.

Hopefully, it will be the plugs. If they look worn then they need replacing. They can develop firing problems that are not visible. I have an aircraft bomb testing machine that tests them under pressure. You can then see the problem easily.

From reading some of the threads, spraying into the TB should have let the engine run for a few seconds. I have never used that technique. Sounds more like no spark. Change out those plugs and see what happens.
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Unread 11-05-2009, 11:16 AM   #7
sixone
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Okay, will replace them tomorrow.. and post the result here. Any other things to test before i replace the plugs?
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Unread 11-05-2009, 02:57 PM   #8
sixone
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Because it was too late and all the stores were closed I decided to give it another try and clean the plugs thoroughly. This time i used a blowtorch and some sandpaper, also i adjusted the gap. After all that, they looked like new.. put them back, and .. after a few cranks it started.
Now it runs fine.. i started it couple of times again to be sure and started every time.
Anyway i will replace the plugs by the end of this week, but wanted to let you know what was the problem..
jeep210 was right.
thanks.
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