Yes, Another No start.

1988, straight 6,

Ok this is what i got,
Fuel is good, at the right PSI and holds pressure.
New red top.
New spark plugs and wires, cap, rotor.
New coil.

about two weeks ago i could start the jeep with a little spary of starter fluid and she would run great. If i shut it down i could start it right away but if i waited 30 minutes i would have to spray more starter fluid to get it going. Just crank and crank and crank and no go.

I think my problem is the ICM. Using my meter i can touch the positive side and the light will light up. When i do the reverse on the negative side the light does not come on showing the the circuit is good. I have done the same on the plugs(that plug into the ICM) and they test good. when i try to start it and ground one of the spark plugs i get no spark.

any thoughts?
Hasta

Fuel pump power modes:

1. Key to ON, B Latch relay powers pump for 3 seconds. Power provided is a full 12 volts bypassing the ballast resistor. After the 3 seconds the ECU will cut the power if it hasn't received a signal from the CPS/CKP.

2. Key to START, engine cranking, power to the pump is through the starter relay. Power provided is a full 12 volts bypassing the ballast resistor.

3. Key to RUN, engine running from idle up to just short of WOT, power is supplied to the pump through the fuel pump relay, through the ballast resistor, where it is reduced approximately 6 volts.

4. Key to RUN, engine at WOT, power to the pump is supplied through the oxygen heater relay, power is a full 12 volts bypassing the ballast resistor.

Sounds like you aren't getting power to the pump when the key is in the ON or START positions, or both.

:link1:

First off, Thank you that is the first thing i troubleshooted.
the fuel pump is fine, and gets power. It and the tank were replaced 6 months ago, old one was rusted. I even removed the gauge and let it spray fuel while i cranked it to make sure, shot clear across the drive way, 8 to 9 feet. Oh and i have bypassed the ballast
is there a condition where the pump could cause a no spark?

I don't think so.

Look. If you have a no spark condition you could spray ether into the intake until the second coming, but it won't start.

If your spark is very weak, maybe the ether is helping, but then you can start it shortly after a shut down without the ether, so that probably isn't your problem.

Get it to the crank/no start condition and confirm the presence or absence of spark.

I can confirm the no spark, and have a ICM coming. It is possible that i have two problems with both fire and fuel. time will tell and I will post up.
Then i will work on the XJ BBQ....:repair:

To confirm. The engine currently does NOT start no matter what you do and has no spark?

1. For a no-spark condition, the crankshaft position sensor is still in play. With a faulty one, you will not have spark and you will not have fuel going TO the injectors. The crank sensor is located on the bellhousing and can be tested for resistance.

2. Haven't seen any mention of the "ignition control module", part of the coil assembly on the 87-90 4.0. It can be serviced separately. Doesn't seem to fail as often as the coil itself but should be tested for ANY ignition problems where the cause isn't obvious.

3. Keep in mind that new parts can and do fail. Testing of your ignition coil for primary and secondary resistances is not a bad idea.

birchlakeXJ said:

To confirm. The engine currently does NOT start no matter what you do and has no spark?

1. For a no-spark condition, the crankshaft position sensor is still in play. With a faulty one, you will not have spark and you will not have fuel going TO the injectors. The crank sensor is located on the bellhousing and can be tested for resistance.

2. Haven't seen any mention of the "ignition control module", part of the coil assembly on the 87-90 4.0. It can be serviced separately. Doesn't seem to fail as often as the coil itself but should be tested for ANY ignition problems where the cause isn't obvious.

3. Keep in mind that new parts can and do fail. Testing of your ignition coil for primary and secondary resistances is not a bad idea.

Click to expand...

Well i swapped out the ICM and tested both for resistance and they check out fine.


oh and still no spark and start.... Time to check the CPS.

Well after 30 minutes looking for the right tools, 10 minutes getting dirt out of my eyes, and about 15 minutes working the jeep is back running. The CPS was bad.

AFTER ACTION REPORT
had fuel pressure, but upon further inspection no gas in the cylinders.
No spark but the coil and ICM were all working.

The CPS had good wires but the magnet was very corroded.

Now the new question, there is a cable that runs to a small lever on the transmission. the cable is attached by a plastic clip. the lever is small and towards the front of the tranny (automatic). I broke that clip, what is it called?

87-90 Parts Catalog just shows the cable, bolt, and an o-ring.

Looks like a new cable is required, unless you can fab something.