urgh, need help with motor

ok, heres the scoop, 92 xj, 4.0 HO, got a 8 gal. fuel cell, all fairly new sensors under the hood, runnin the master e2182 fuel pump, never given me problems. ok, so the jeep won't crank, it gets so close to starting, ive never seen a motor get this close to turning over without actually starting. it sounds like its a spark problem, but i checked the spark and the coil is getting it. also, sometimes it will diesel out which is weird. i know that its getting fuel, the pump is wired to a standard on/off switch, and i've checked the lines under the hood at the fuel rail to make sure that its getting fuel. i'm stumped, also, if i leave it for a while, it will fire right up, run for about 100 yds and then just cut out. anybody have ANY suggestions? Eagle, beez, any other gurus out there got somethin for me? its sittin on the side of the road right now until i can borrow my buddys trailer to go and pick it up unless i get it started today or tomorrow.

It might be the CPS, I had the same problem a while back. Just clean the connection and see if it helps. I think lots of people have left for Moab.

First, correct your terminology. If the starter is making the engine revolve, that IS "turning over," and that IS "cranking." What it is not doing is starting.

CPS is by far the likely suspect. You wrote that you have spark at the coil -- did you check to see if you have spark at the spark plugs? How strong is the spark? It should be a good, strong, fat, bright spark, not a wimply little glimmer.

Aha -- I just read your post again. Start and run 100 yards? How's your ballast resistor in the fuel pump circuit? The start circuit bypasses that, so the fuel pump would run when you engage the starter, but as soon as you release the key to the RUN position, power to the fuel pump goes through a ballast resistor. Not sure where that is on a '92 -- on my '88 it's located on the insode of the driver's side front fender, next to the air box.

well i just bypassed the ballast resistor when i put in the new pump and fuel cell. that little thing gave me hell before so i just took it out and connected the two wires. sorry about the terminology, my mind is thinking faster than i can type and things are getting jumbled in my head. i'll check the spark at the plugs tomorrow, what could it be if no spark there?

jeepxjga said:

well i just bypassed the ballast resistor when i put in the new pump and fuel cell. that little thing gave me hell before so i just took it out and connected the two wires. sorry about the terminology, my mind is thinking faster than i can type and things are getting jumbled in my head. i'll check the spark at the plugs tomorrow, what could it be if no spark there?

Click to expand...

Okay, you connected the two wires, but that's still a different circuit than the start circuit. Check the connection where you made that bypass.

If you have spark at the coil but not at the plugs, it could mean a bad distributor rotor, a cracked distributor cap, or bad plug wires. Or even bad spark plugs.

Also check your fuel flow. You may be getting enough flow to provide you enough pressure at start up, but the pump can't keep up and keep the engine running. This can come from a cloged fuel pick up, inlet filter or a faulty pump. I would first check all of the connections like Eagle suggested though.

alrighty well, since its sitting on the side of the road i'll check the obvious stuff today and see what i can figure out, if not i'll just get it towed back home and fiddle with it here in the apt parking lot