still having trouble with my 88 xj

[Cherokee Freak]

It totally sounds like either the fuel pump and or the ascender which are in the tank have crapped out on you. Both of which will quit suddenly without notice. When you click the key one notch, can you hear the fuel pump engaging? In the engine compartment, when you hit the valve on the fuel rail, do you get a small squirt of gas?

 

[88 Wagonman]

all of those where installed yesterday with brand new parts all wires the cap and rotor aswell as new plugs. If i messed up the install of the distrib could the timing me so far out that it would stop the plugs from sparking ?

No, it would still spark. Where did you check for power on the coil? While cranking check the green wire to see if you have any voltage.

 

[jolly_rogger]

k i spent some time on it today again and it still won't start. I turned the key and heard a noise from the gas tank area kinda like a click and the buzzer in the dash goes on when you fist turn the key. I tried reinstalling the distrib as i may have done it wrong the last time and thought what the hell i might aswell. Put a spark plug in the line going from the coil to the distrib and had my wife turn it over ... and guess what nothing happend. i thought that as my bat was pretty much drained today i would try this again after hooking it up to my wifes xj while hers was running to try and boost the power, but after waiting awhile i tried the test again and to no surprise there was no spark. i am at my wits end with this thing.

Is it poss to install the crank position sensor wrong ?

If i installed the distrib wrong i would still get a spark from the coil wouldn't I ?

 

[88 Wagonman]

The distributor could be sitting on the floor and you would still have spark at the coil. As far as installing the CPS wrong you would have to really try hard to make that happen.

 

[jolly_rogger]

then why am i not getting spark ? what am i missing ? could the ECU stop it from sparking ?

 

[88 Wagonman]

Yes, the ECU can stop it from sparking. Have you checked to see if you are getting voltage at the green wire going to the coil while cranking?

 

[jolly_rogger]

no i have not tried that again as my bat needs to be recharged. i will try that tomorrow though. if there is or isn't voltage at that wire what would this mean and what would i be looking at replacing ? thanks again for the help. i have never had so much trouble with a jeep.

 

[88 Wagonman]

It would mean that you are not getting a pulse signal from the ECU, now that doesn't necessarily mean that the ECU is bad, because if the ECU is not getting a signal, it can't send one, but if you are getting a pulse signal, you can pretty much rule out the CPS and ECU, at least that part of the circuit. Tomorrow I will try to check my 88 for some reference voltages so you know what kind of numbers to expect. Right now the wife drives it. It may sound funny, but she drives it because it gets better gas mileage than what I am driving, and she drives more.

 

[jolly_rogger]

thank you verry much

 

[jolly_rogger]

i guess i could always test my wifes xj for the same results as yours as she has a 90. but i would still like to know what you get for voltage. thanks

 

[5-90]

Dumb idea - but try "jumping" the chassis ground to the battery negative post, and see what happens. That stupid little "ground strap" between the cylinder head and the firewall is the only ground path for the chassis, and that going silly will screw with the ground reference for the ECU. This can cause all sorts of trouble...

 

[88 Wagonman]

Dumb idea - but try "jumping" the chassis ground to the battery negative post, and see what happens. That stupid little "ground strap" between the cylinder head and the firewall is the only ground path for the chassis, and that going silly will screw with the ground reference for the ECU. This can cause all sorts of trouble...

Your right, dumb idea, I realized that today when I went to test my 88. I realized that I had it confused with another ignition system that I had worked with in the past. Sorry for the mix up.

 

[jolly_rogger]

so should i or shouldn't i try that ?

 

[xjtrailrider]

so should i or shouldn't i try that ?

It can't hurt anything. You are just adding another ground or a ground at all if there is none. I have a OPTIMA red top in my 90 and I used the extra ground side post for an added chassis ground and immediatly noticed my lights, etc were brighter, things worked better. If you trace the ground curcuit on a XJ it goes from battery-engine-chassis. If the strap at the rear of the head/firewall is not making good connection then you have little or no ground at the ECU. There are 3 other ground connections at the dipstick tube holddown bolt. Take them loose and clean them good and re-tighten.

How does everything else work, are the lights bright, etc.?

 

[jolly_rogger]

well i didn't get a chance to check those today but i did manage to try a volt test with my dig multi from the coil wire that goes to the distrib and i found that i had about 12.53 volts when the key was turned on and about a 2 volt drop under cranking. not sure if this helps. I thought it was supposed to jump to around 40,000 volts which may fry my multi but at this point i don't care i just want this thing to run. I would love to get out on the trails. This sat i will be going through all the wires and if it isn't running by then i'll lighter up it and pee on the ashes.

 

[jolly_rogger]

okay i spent all day on the damn thing yesterday an it is still not starting or getting spark. i don't know what to do...should i just light it on fire or put up a sign "5 dollars a swing" ? i'm starting to hate this thing. Yesterday I replaced the map sensor, all grounds,ecu, oil sending unit, o2 sensor, a number of conectors and reinstalled the crank sensor. WTF am i missing ?

 

[Ecomike]

I am reading this thread for the first time. So here are my thoughts as I read each post.

First, while the renix will start with out the CTS connected (I know as I have done it), I also know that if the IAT (Intake Air Temperature, or also called an MAT) sensor is posting bad data to the ECU it can cause a no start problem by feeding gas too lean or too rich, and I therefore suspect that a bad CTS could do the same thing. I had a no start when cold issue that drove me nuts for weeks that turned out to be a biased IAT sensor telling the engine ECU it was hot when it was in fact cold. Started fine once it was hot.

You might try disconnecting the IAT (also called a MAT) and CTS to see if the ECU start up table data will start the engine with no live temperature data. Or do the smart thing and test those two sensors while disconnected from the harness to see if they have the right resistance readings.

Post # 16, fuel filter new, ? was it installed backwards, or did the inside of the fuel filter hose colapse?

Post #20. Yes, if the engine was at the wrong stroke of TDC on cyl #1 it would try to spark at the exhaust stroke instead of sparking at the intake stroke. It is also also easy to install the dizzy off by one gear which messes with the acceleration and power (timing) but does not cause a no start issue. But neither would casue no spark.

Sounds like your problem is with the HV coil or the ignition control module that sits under the High Voltage coil. Try swaping the HV coil from your good XJ first. If that does not work then try swapping the HV coil and the ICM (Ignition control Modual) from the good XJ (or try both first, then try them one at a time if both solve the problem to see which one is bad, or if both are fried). If that works you know which part(s) are bad. If that does not work then you may have a wiring problem between the ECU and the ICM, which we can help with, but try the HV coil and ICM from your good jeep first. Also, the HV coil input from the ICM is a pair of brass clips that can get old dirty and loose, check them for good contact before you write off the old parts!!!

 

[Ecomike]

Also, you have most likely flooded the engine with gas by now. Check the oil for gas odor. If it smells like gas change the oil immediately.

Also, until you get a known spark and get it started, hold the gas peddle to the floor while cranking during tests, as this will tell the ECU to shut off the fuel supply and keep it from flooding. That will also dry out the spark plugs and cylinders when they get flooded from a no spark problem. Once you get spark and have a dry engine let off the gas peddle so it can get gas and start.

 

[jolly_rogger]

it's not flooded as the plugs seem dry. and i don't smell gas in the oil. i have swaped coils completly from my wifes 90 xj which is the same and still no spark.

 

[78/xj88]

My 88 does the same but always starts back up after cranking and going CRAZY on the side of the road. I will toss parts at it and it will go and then right back on the stall no start path i love the stress!!!! But it has NEVER left me stranded ! Any how i am Sea Foaming it as soon as it gets dark. Dont know if that will help but it likes the time i spend with it it always runs good after a long night of some good ole 1 on 1 .lol it strange but oh so true...........:confused1