Help, Spark issue

Today I removed my fuel rail to change the O-Ring seals on the injectors because of ari bubbling and fuel leaking out of a few of them.

Before I removed the fuel rail I was able to get the jeep started. It ran fine but was leaking the fuel from the leaky seals.

I have another cherokee that I have removed the fuel rail many times on, and i know what im doing in that respect.

So, i got the o-rings replaced, injectors in the rail and seated the rail into position. I bolted down the 4 bolts, reconnected the injector wires, and then reattached the throttle cable bracket, and everything was good to go.

I went to start the cherokee a and nothing, it sound like its turning over fine, i checked and it is getting fuel. So i removed all the spark plugs and cleaned them. All 6 were wet.

So i put the spark plugs back in and it still wont start. So i took one spark plug out and tried turning over the motor to see if the plug was getting spark, and well its not.

Im not sure what may have happened. The car started RIGHT UP before I removed the fuel rail, but now it wont start and the spark plugs are not getting spark.

Anyone have any advice, could I have pinched a wire on the intake side of the motor. I checked to make sure all the plug wires were connected to the dis. cap and the coil pack wire is tight.

I just dont get it, starts one min then not the next. HELPPPP!!!!

If i pinched the one of the wires for the Crank Position Sensor would that cause NO spark to go to the spark plugs? I know the CPS wire is attached to the far bolt on the fuel rail.

no signal from the CPS would cause no spark...

If the plugs got real wet with fuel it could have fouled them. Are you getting signal to the coil to fire. Check the negative side as you role the motor over and see if the coil trips.

An unplugged MAP sensor or disturbed vacuum lines to the MAP sensor can cause it to run pig-rich and not start.

McQue said:

no signal from the CPS would cause no spark...

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Agreed. You have to find the root cause of the no-spark.

If you had spark before this fuel injector job, and you have verified NO SPARK after doing the work, gotta look at cause and effect.

You didn't mess with anything else, so you should concentrate on that crank sensor wiring and connector near the firewall/#6 injector. Did you try unplugging it and plugging it back in? Inspect that wiring?

birchlakeXJ said:

Agreed. You have to find the root cause of the no-spark.

If you had spark before this fuel injector job, and you have verified NO SPARK after doing the work, gotta look at cause and effect.

You didn't mess with anything else, so you should concentrate on that crank sensor wiring and connector near the firewall/#6 injector. Did you try unplugging it and plugging it back in? Inspect that wiring?

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First off for the OP--hand slap for not sharing your BASICS with the rest of the class--year/engine/etc., but you get a "star" for explaining your problem clearly.

BirchlakeXJ wins the cookie.

You have verified no spark--that is the issue to resolve.

Yes, if there is no spark then there are a number of likely suspects: the ignition switch sends 12 volts to the ASD or B Latch relay, and that relay sends 12 volts to the ICM or coil. The ECU or PCM controls the grounds for those relays as well as the ICM or coil for collapsing the primary side and triggering the spark out the secondary side.

Without a signal from the crank sensor the ECU or PCM isn't going to do ANYTHING in the way of triggering the spark, and without the ECU or PCM the ICM or coil isn't doing ANYTHING either.

Test your CPS resistance--can't tell you the correct procedure for your year/engine because we don't know the BASICS.

Good luck.

Ahh, I missed that bit of information.

The vehicle in question is a 1996 Jeep Cherokee Country 4.0 6Cyl Auto (259K on the clock)


Thanks everyone for all the help. I checked the wiring on the Crank Sensor and it seems as if one of the wires was pinched causing the wire to break.

So now the question is, how in the world do you get at the two bolts holding the crankshaft position sensor in. I tried so many ways to get at it with out luck. I can barely get my hand in the space let alone any tools.

From underneath, couple three extensions.

BE CAREFUL and don't drop those bolts into the bellhousing. First, they are a special shouldered bolt to position the crank sensor for the correct air gap to the flexplate. Second, if you do drop one in their you might have to pull the trans to get it out.

Some people put a jack under the transmission, then loosen the crossmember bolts/studs (two bolts and two studs per side) then lower the transmission tail a bit to increase the working room.

Some have reported having a second pair of hands up top helping to guide the socket on helps.

Good luck.

Question: are you pulling the crank sensor? Might be easier to just solder in a section of wire for a repair.

joe_peters said:

Question: are you pulling the crank sensor? Might be easier to just solder in a section of wire for a repair.

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My thoughts exactly. Easier to repair that pinched wire.