Spark Issue

[jpolen]

Is there any way to check to see if you have a faulty Crank Shaft Position Sensor? I had sank my XJ into a water hole last year and was having problems getting it to turn over found out I had to clean the NSS got that cleaned and now I got it to turn over but it doesn't seen to want to fire all the time, what I mean is it will fire once and a great while. The cap and rotor look ok and I seem to have weak spark at the coil thinking it could be my CSPS or my coil but am trying to find ways to test everything before I just start replacing parts. Would really like to test CSPS and the coil before just replacing them. Any help would be great thanks in advance.

[4.3LXJ]

Justin, the CPS does not affect the spark. It tells the computer when it can fire the injectors. So I am a little confused as to whether you have a fuel or spark issue here.

[jpolen]

It is a spark issue I am pretty sure the spark at the coil seems week. I am just getting to the point of not knowing what to do considering there is a run in 3 weeks and this is the only weekend I really have to work on it. I thought there was a sensor that told the coil when to fire I could be very wrong. It's like it has to turn over 2 or 3 times before it will fire and sometimes it still doesn't fire. I guess I am just looking for ways to test everything before I just start throwing new parts at it.

[4.3LXJ]

Is it turning over slow?

The sensor you are talking about is a cam position sensor and is located in your distributor. But you might also have a starting voltage issue. Check your connections and if it still turns over weak, then hook up some jumpers to it and use another vehicle to charge the battery fully and try to start it using the jumpers too. You might have a weak battery and may need to change it out. If you can check the voltage, do so. A fully charged battery is 12.6V

[jpolen]

Its not that the motor turns over weak it. I got it to fire, but its like its not getting spark all the time. To tell you the whole story on what happened last fall I was out wheeling and went to go through a mud hole and drop the drivers side front corner down in the hole and it died aka ran out of fuel. So we pulled it out and put 10 gallons in it and tried to start it all we could get it to do was fire so I pulled it back to the house. After getting it back to the house and finding time to work on it, it would fire outside but that was it. So we pulled it into the shop and had nothing. The NSS was dirty. I finally had time to start working on it again this weekend and jumped the NSS for the time being meaning I have it sitting on the bench to get cleaned. So today when I went to fire it up all I can get it to do is turn over and fire once and a while. I know I am getting fuel but the spark seems weak so I pulled the cap and rotor off and cleaned them up with some emery cloth. Reinstalled the cap and rotor and still wouldn't fire the way it should. So I pulled the plugs and wires to clean the plugs and make sure the wires where correct. Put it all back together and still feel like I am at point one with nothing but a fire once and a great while. While doing all this I had pulled the ignition switch out and the plugs fell apart so I now have 8 wires hanging down. The wires are as followed. I have 2 reds a yellow an orange a purple a blue a black with a white strip, and a purple with a yellow strip. I know the 2 reds are hot and the yellow is the start wire and the blue runs the inside chime. But for the rest I have no idea.

[4.3LXJ]

I see. I will have to wait for my wife to get back with mine so I can look at the colors on the wires. But If I remember correctly, yellow is a run wire off the igintion. Check to see if you have power to the coil with ignition on, aka wires tied together.

[jpolen]

If i hook my red and yellow wire together the jeep turns over and when i hook the blue wire its just as if you turned the key to the on position. Its the other wires that i don't know what they do and what there for.

[4.3LXJ]

At least two of them go to the fuse block. One is also accessories. Turn all the stuff on and see what runs and what doesn't

[jpolen]

Well I went out and bought a new coil, cap, and rotor for it, but it still wont fire. I know i am getting fuel due to the fact of we have tested fuel pressure on the truck. What am I missing or what am I doing wrong? I really don't have anymore money to throw at this thing and need it running in 3 weeks. By the way figured out what all the wires do that hook up to the ignition switch.

[4.3LXJ]

Get yourself a test light or something and verify power to the coil.

[jpolen]

Well I have come to the conclusion that my timing must have jumped. I have spark and fuel but it wont fire or back fire unless you put the distributor 180 off. So I have started pulling everything off to get to the timing cover, but ran into the problem of no pulley puller to remove the harmonic balancer so everything is on hold till tomorrow. Thanks for all the advice Steve. I do greatly appreciate it.

[4.3LXJ]

Justin

Before you disassemble half of the Jeep do a small check that won't cost you anything. Take out #1 spark plug and crank the engine over slowly. Air will come out the spark plug hole and when the air finishes coming out the timing mark should be in the ball park for top dead center. If that is the case, then it is probably good. There is an article here posted my Mudderoy on timing the distributor.

[cantab27]

how wet did it get

[jpolen]

Well it died in the mud hole and was pretty darn wet. Ok I will take a look at the thread and see if maybe the distributor is off, but I did have a Chysler mechanic look at it and reset the distributor. Doesn't mean its right we might be off a tooth or two.