dreadd

92 cherokee I6 4.0L Automatic.

For the last 3 weeks or so I experienced intermitten starting issues. I would have to attempt to start jeep 4 times then it would work fine for a week then back to unable to start.

Now its unable to start at all. Just cranks. On occasion it will act as if it is going to fire up but doesn't. Mostly just cranks. Previously, when i first starting having the starting issue it would always act as if it was going to start then die out.

About a week ago i replaced the distributer cap and rotor, all the plugs and plug wires. I had the starting issue before and after this change.

I have replaced the fuel filter.
I removed a spark plug and tested for spark. It's definately sparking!
I replaced the CPS sensor, same results.

If i spray starter fluid into the Throttle body it will start and stay running as long as I provide it starter fluid. Once i stop the vehicle dies.

When i turn the key to the 'on' position I can hear the fuel pump engage

I removed the relay for the fuel pump and tried cranking it (as friend suggested). After cranking for about 8 seconds it went back to acting like it was going to fire up symptom.

Im not sure where to go from here, do I switch out the fuel pump next?

fonman25

It's really easay to borrow a fuel pressure gauge from Autozone or similar, and just test the fuel system. dont spend a bunch of money on a fuel pump if you don't need it. You hear the pump running, and it might be fine, but it is also possible for it to run but not be putting out sufficient pressure to start the engine.. Without a pressure gauge, you won't konw. Another possibility is that the pump is fine, but the injectors may not be firing. You can use a long screwdriver as a "stethescope" with the handle against your ear, and the tip on the body of the injectors to see if you can hear them clicking as the engine is being cranked over by an assistant. If you hear them clicking, then you can be pretty sure the problem is in your fuel pump, or the fuel pressure regulator. Good luck,

Corey

dreadd

Thanks for the reply Corey. Where is a good spot to hook up a pressure guage? And do I test it with car off, cranking or both?

ET JEEP

Yes, don't throw money at it without finding the cause of the problem.

If you stand in front of your engine, you will see a long tube with the injectors. This is the fuel rail. Towards the front you will see a cap on the fuel rail. Remove the cap and you will see a valve similar to a tire valve. Use a rag around the valve and push in on the valve. This will release any pressure in the fuel rail and fuel wil come out. Now attach the pressure gauge to this port.

Normal engine running pressure is about 30-35 PSI. You shoud see some pressure with just cranking engine but not sure how much. As suggested check the injectors. Your engine may have a fuel pressure regulator in the engine area. Not sure, but that should be checked also if it is there.

Since the engine runs with starter fluid, you are just not getting fuel.

dreadd

I haven't tested the fuel pressure yet as mentioned below. Im going to try to get my hands on a fuel pressure guage. I do see the nozzle that the gauge would attach to. If i go and purchase a gauge do i need any sort of attachment to hook it up?

Also, I did not mention that the "security" light on the dash has been on the entire time i have owned the Jeep (about 4 months). Could this be relevant? Thanks!

shoytjr

Had the same problems witrh a 1987 cherokee finally found the electrical connector on the firewall was the issue. Seperated the connectors and found the grease used to protect the connections became like tar. Cleaned the connectors and used new grease, works like new.

RATTLESNAKE

I just had the same problem, the only difference is it wouldn't stay running, I cleaned the connections on the ceramic piece on the firewall with a copper brush and it started right up and remained running.

Siv

I just recently purchased my Cherokee and have the same issue. However I couldnt locate the connector and was wondering if you could possibly take a picture of it. Thanks

freegdr

picture of what the ceramic pc mounted on drivers fender well by air box

cpnwrench

Might be the dumbest thing ever...but.....

the "security" light is something in your system which MAY be preventing the fuel pump relay from engaging, ergo, no fuel pump, ergo no fuel pressure.

now, on a 92, I am not familiar with this feature as I don't have this.

but,,,, once you clear this...... (remove both terminals from battery for at least ten minutes )........leaving all doors unlocked before you do.

if you have the manual, may be something as simple as pulling the fuse that supplies the security feature......dunno... just speculating.

if you figure it out let us know! I for one would like to know what the heck.

cheers!

cpnwrench

cpnwrench

Another thing....REALLY might sound dumb.......


is the fuel filter you replaced in the correct way?

i seen dumber things....

cpnwrench