The beast is dead.....

[CRASH]

......hopefully temporarily!

I was headed down FH road when all of a sudden......it shuts down with not a hint of warning. Shiznit, I thought, the CPS took a dump. Checked it, hardwired it, nothing. After about a half hour, it coughs, coughs, and restarts. Headed for home, and after a mile, it shuts down again.

Long story short, got a tow home.

Got home, changed the CPS, nothing. Checked the fuel pump relay, negative. Pulled thefuel pump, and this is where it gets interesting.

The pump runs when the key is in start mode, when it's getting the run signal from the starter, as soon as I release the key, the pump shuts down. This is why the rig will start temporarily and then die, it gets full pressure for just a couple of seconds.

Checked all the fuses, and everything is intact.

Anyone ever seen this condition? I did smell something electrical as i was coasting to a stop the first time, so something must have shorted somewhere. It was outside in the rain for a while, maybe something got wet (the old bitch leaks like a sieve)? I just don't know where to check next.....

Advice, cheers and jeers gladly accepted.

CRASH

 

[Jes]

Well, that sucks.
May I suggest you go over to that forum you probably have never seen, it's called "OEM-tech" on . :wink:
This sounds like something that Eagle or 5-90 might be able to diagnose.
Good luck my friend.


Jes

 

[Bryan C.]

Check for a burned fuselink, look by the battery near the solenoid bolted to the fenderwell for the melted link. If you had a burning smell then that is most likely the problem. The pump gets power from a different source when turning the key on than when it is running. Now you still need to find out why the fuselink burned. Check for any shorts in the fuel pump circuit. It usually takes a few tries to find the root cause of the short circuit.

 

[Stoney]

I KNOW I KNOW I KNOW!!!!!!!!!!!!!!!!!! remember the reason bryan's wasn't working? well anyways there is a little white box on the fender well that has two wires pluging into it. it controls the fuel after the key is let go. it might have gone bad (?) or maybe just a loose wire!!!!!! if u don't know what i mean call me i'll tell you!!(916) 223-5795. hope that helps!!!!!!!!! whoo hooo i might be right for once!!!!!



kent

 

[scrappydak2]

hey have you tried switching the relays around to see if it is a bad realy?????

 

[CRASH]

Checked the relays, they are fine. In fact, the fuel pump on the old rig runs without the relays in.

I thought about the ballast resistor, Stoney. I looked at it, and thought: how could that go bad? I'll check it as soon as the rain lets up a bit. I'll swap the one from the hoopty Jeep.

Bryan, I didn't realize there were fuses over there? I have an '88. I'll dig around a bit.

Thanks for the help, y'all.

CRASH

 

[FarmerMatt]

My suggestion would be to give it the proper burial it deserves . Get your butt in gear & get the new one up & going since your wussing out on JV. If you want I can trace the circuit in my FSM if you don't have one. Also keep in mind that the fuel pump will only run when it needs to via a pressure switch so after you turn the key on it will pressure up, but than wait until it see's a need for pressure. At least this is how my sub works.

 

[norcalxj]

i would have to say it is the ballast resistor.

 

[Goatman]

Any luck yet , Andy?

Sounds a little like what happened to me in Moab. It died on me when I climbed at Last Chance Canyon two weeks before leaving for Moab, and we found a crack in the vacuum line leading to the MAP sensor, fixed it and it ran fine. Then it started dying on me when I stepped on the gas as I was leaving Bakersfield, and I picked up a TPS as I was leaving town. Ran fine as far as St George and then it started dying intermittently on the freeway. We stopped and replaced the TPS, and it wouldn't stay running as we pulled out of the parking lot. We put in a new MAP sensor (I carry a spare) and it ran fine all the way to Moab. Pulled up to the first waterfall on Lower Proving Grounds and it would die as soon as I started up, over and over......bummer! In camp we cleaned the contacts on all the relays, then it started dying right away when it started up. Put a jumper across the leads to the ballast resisitor and it ran, pulled the jumper off and it died....over and over. Put connecters on the wires and bypassed the resistor and it ran fine, but it burned the fusible link to the ignition while I was rolling up the windows, without the engine running. NOW WHAT!! Twisted the wires together on the fusible link and it ran, so went to the parts store and got some spare fusible links in the morning and headed out to Cliffhanger behind the group. Pulled up to the first climb and it burned the fusible link and died AGAIN! This happened repeatedly as we pulled out different combinations of fuses, but now at least we knew that there was a short somewhere in the ignition circut because the fusible link would smoke every time it died. We wire tied the harness under the dash and it ran on up the trail and we met the group coming down. We went down a ledge and it died and burned the fusible link again, and then did it over and over until Mike Rollins finally found the short. The ignition wire in the front harness had rubbed through and was shorting out in the left front corner where the harness goes through that triangular brace that the horns are mounted to. Fixed the short and it has run fine since. This probably has nothing to do with what your is doing, but I feel your pain. :?

Have you replaced the ignition module (coil)? This is the most common cause of the engine just quitting and not running again. I also carry one of those......

Richard G

 

[CRASH]

Still dead!

Facts:

The pump is running only when the starter is cranking.

In the spare Jeep, the pump will run in the key = ON position withthe computer, and the fuel pump solenoid pulled. This seems odd, but there it is.

Traded the ballast resistors from rig to rig with no effect.

Next Step:

Pull apart the wire looms and look for shorts and check for continuity.

CRASH

 

[Gary E]

Can you hardwire the pump just to verify thats the problem? perhaps its running just when you turn the key on to build up pressure and thats all it needs for awhile?

Hunting down the circuits is fun break out that ohm meter and check your continuity between points and grounds, but you allready know that

Maybe she is just bucking cause she knows you are going to dump her?

 

[CRASH]

yup, I hardwired the pump, and it runs continuously with no problem, and makes almost 40 pounds of pressure.

I hate dealing with electrical issues.....I have no patience.

CRASH

 

[Gary E]

Considering that jeep has a life expectancy of what? 2-3 months I would be sorely tempted to tap into the wire somewhere near the front and wire it to a switch or to the accessory side of the ignition switch, like a car stereo. I probably would throw an inline fuse in though.

maybe the installation of a switch would be more fun so you could call it an anti theft upgrade :wink:

 

[CRASH]

Now you're thinking like me! I thought about this pretty hard on Saturday, but thought it might be a little too booty-fab.

Hmmmmmmmmm...................

CRASH

 

[Stoney]

Bryan said to try your computer. when his was doing the same thing he changed his computer and it made it run.