89 Cherokee Starting Problems - Help Please
 

I have a 1989 Cherokee 4.0 6-cylinder with 210,000 miles. It will start and acts like it wants to run a couple of seconds, then it dies. It will keep turning over as long as you turn the key but it won't fire up and actually run. It was previously running great until one morning when the present symptoms suddenly appeared.

I've checked and/or replaced the ignition system components, but have noticed the spark from the ignition coil wire is strong for about two seconds and then the spark stops. If you turn back the key to the off position and then re-start, the spark is strong for about two seconds again and is then gone. Shouldn't the spark be going as long as you turn the key in the regular starting sequence?

I have also noticed that gas trickles out of the fuel line at the fuel filter during the starting sequence. I checked and re-tightened the connection. The leaking is on the side closer to the engine as if there is a blockage, but I also checked at the fuel rail and there appears to be good pressure and plenty of gas coming through during the start sequence. Could there be some kind of malfunction with the fuel pump and maybe this is causing the starting problems?

This is very puzzling and any help would be very appreciated.

Thanks,

Joe

Cheek spark at the coil and cheek the wires at the coil. As far as the fuel IDk. Possible Computer issue. Get yourself a repair manual.

89 Cherokee Won't Start
 

Thanks for the comments, however, I do have a repair manual and have studied and checked all the suggested components in the ignition system. Yesterday, I switched out the ECM and the same symptoms continue. I have checked for spark at the coil and distributor; there is spark at both. I'm beginning to think this is a fuel pump problem, however, there does seem to be plenty of gas at the fuel rail. Very puzzling. I've tracked down other occasional problems with this vehicle in past years and fixed them, but this one really has me stumped.

Joe, You fuel pump can still be bad even if it "appears" to have good pressure at the fuel rail. This appearance of good fuel pressure at the rail sent me in the wrong direction as I was troubleshooting my son's 87 XJ. You have to actually connect a fuel pressure gauge to the test port on the fuel rail. Turn the key on even without starting once it is primed, you should have 30 PSI. If it is anything less than 30, your fuel pump is bad. If you have 30 PSI, you then need to disconnect the vacuum line at the fuel pressure regulator (forward most point on the fuel rail). The pressure should jump up to 38-39 PSI. If this doesn't happen, then your fuel pressure regulator is bad. I hope this helps.

When is the last time you did a good tune up plugs,wires,cap button,ignition coil,fuelfilter,air filter,oil,fuel system clean ect.

Response re 89 Cherokee
 

Thanks for the comments about this problem with my 89 Cherokee.

I will get a fuel pressure gauge and test to see if that is the problem. The fuel pump does activate when the key is in the start-up position, but you are right, it is possible it is not working efficiently. Thanks for the advice and I will measure the pressure.

Regarding the suggestions from Gabe about tune-up, cap, etc., yes, those are all newly done and up to specs, etc. I also replaced the coil, wires, plugs, cap, rotor, etc. and there is no change. Thanks for the suggestions.

did you test the cps? it maybe the issue.

Been gone awhile and failed to see this post. Buck has you checking the correct thing. If you have spark and the fuel pressure is up to par then it should at least try to start. Let us know what kind of pressure you get.

hey listen here mr. , no more breaks for you:rofl:

Sry had to go out of town. If it helps it wasn't on a pleasure trip.

Have you hooked an ohm meter to your coil? I wonder if it has a break in the windings that won't allow it to become saturated enough? You said it's new though...weird.

All the above suggestions are great, but I don't think the fuel pressure will have anything to do with a weak/no spark condition. The CPS could, though. You may want to check that out. 7/16" wobble socket on 1/4 drive is the way to go on that one. There's always a tool for the job to cut the stress in half.

Post back with your findings, but the general symptoms DO sound like a fuel supply problem.

I wish someone would elaborate on that little piece of porcelain over on the driver's side fender close to the firewall. It looks like a coil resistor. Isn't it true that it is supposed to "quieten" the fuel pump? Is it correct that you can just splice the two wires together and remove it from the circuit? What's the story here? It can cause a no start condition, correct?

Possibly related....short version: I have a 89' that had low pressure at the rail. I didn't use the vehicle much and wanted to sell it "as-is". Due to the lack of response from potential buyers I dropped the tank today and pulled the pump.

Here is what I found:
http://img.photobucket.com/albums/v1...p/HPIM3096.jpg
http://img.photobucket.com/albums/v1...p/HPIM3098.jpg

The rubber hose connecting the pump to the bulkhead sits in fuel any time the tank is more than 1/2 full. Eventually the fuel will breakdown the rubber and when the pump tries to build pressure the hose will fail. When that happens the pump will recirculate most of the fuel and won't be able to build adequate pressure to start.

Not saying this is your issue, but it is a possibility.

A symptom is you will have fuel at the rail but inadequate pressure. If you turn the pump off the fuel pressure will almost immediately drop to zero. There is a check valve (ball) in the pick up (not in this photo as it was being cleaned). If that check ball was stuck it would act like it was out of fuel too.

Good luck.

Hehe, I know how that looks... Reason I bought a fuel pressure gauge. It would have saved me a LOT of time. And trouble.

Joe,
I had the same prob you are quoting. Thanks to the great info that Blue, Anthony, Gabe and Buck gave me and $250.00 in parts. I finally replaced all I could and decided to drop the Fuel tank to see if it had water in it. When I tried to releive the fuel pressure at the rail there was no pressure. I then decided to pull the pump. I had pretty much the same picture as Quickshoe. I replaced it and after 2weeks of replacing everything else it started right up. Also a 1989 XJ.

The white thing on the fender well is a ballast resistor for the fuel pump. And yes you can "jump" it by cutting off the ends and tying them together.