CJ 258 runs good then immediately dies...

[LaSwampDawg]

I need some help exorcising a gremlin. We recently acquired an all original 1980 CJ7 Renegade , AMC 258 i6 / 4.2l w/ Carter 2BBl. We have half a dozen other CJs and have restored most of them so we are somewhat knowledgeable, but this one has us stumped....It cranks easy, ran beautifully the first day, approx. 75 miles, then all of the sudden stalled, cranked easily again, stalled again...cranked again and was able to make it the 3-4 mile back home. Since that time it has cranked easily, run and revved beautifully in the shop but wont make it a mile or two , before the stalling starts, it seems to be getting worse. Usually cranks right back up with a couple of taps of the accelerator. We cannot isolate the problem.....in the process, we have-
new fuel filter
new fuel pump
dropped and drained tank, new sending unit
new ICM
changed coil
swapped carbs
new cap , rotor
done the CJ "wire jiggle test"

I cant for the life of me figure it out. It will run crank easy, run smooth and then all of the sudden die....??

bought a fuel pressure gauge and regulator tonight and plan to install that and see if that tells us anything. And have plans on swapping distributors this weekend as well.
any suggestions or experiences would be appreciated....if these two don't work , we're going to Marie Laveux with it..

 

[Torxhead]

I think you should determine if it is running out of gas or there is an ignition issue. When you did the fuel tank work, did you replace the fuel lines? as a crack can cause issues like you describe when air enters the system, this would also include the rubber line that enters the fuel pump or even the hard line. Even a fuel tank vent problem can cause similar symptoms. A bad distributor pick up coil and carb can cause problems also.

 

[LaSwampDawg]

Im hoping we'll be able to determine if its a fuel issue with the Pressure Gauge. I have not replaced any lines yet, but inspected them and they appeared ok. if we are losing pressure, I guess we'll have to drop the tank again and start from the back....thanks

 

[Hedgehog]

I'm sorry, but I need your definition of the word "crank". Everybody seems to use the word in different ways.

Does "crank" mean:
... The engine turns over
...The Engine starts and runs
...Does cranking = running?

Is there any water in the radiator?
Just for grins, what does the compression look like?
Have you replaced your spark plug wires, especially the coil wire.
At first thought it seems like you've got a heat related problem.

 

[hole]

Welcome Is the fuel pump mech or electric? I had a stalling issue years ago that took some time before it was found. Electric pumps dont like to suck fuel but rather push it. I ended up discovering a pin hole in the steel line just before the elec pump causing airlock. Found it by carefully filling the tank with air with an air chuck at the tank. It helps greatly to have another person underneath watching and listening

 

[Hedgehog]

It would help some to know how the engine is shutting off .... yes I know that is the center element of the post .... Your observation of exactly how the engine shuts down would help. A sputtering death could be either fuel or electric. A lull in power then a shut don leads me to think "fuel". The engine just cutting off, like flicking a switch, seems electrical to me.

 

[LaSwampDawg2]

sorry for the delayed response. the site wouldn't let me sign back in and the request for password reset emails were never received. From what I've read appears to be a common problem....sad. I had to set up another profile with a different email address. If it happens again, I'm out of email addresses , you may never hear from me again...lol

ok..the answers...

- crank means starts and runs. turn the key, slight rotation and it fires right up and runs. revv's good thru the power band.

- radiator is full of coolant , engine warms to 180 degrees and stays there

- have not checked compression, ...but it does not smoke or burn oil, and runs very strong, when it wants to....

- have not replaced wires , they appear somewhat recent. I can do that.

- stock mechanical fuel pump

- it definitely doesn't sputter. its more abrupt. its a four speed and often happens in the power band, so the pedal goes soft and it just is dead. Sometimes you can push the clutch in a rev it back to life.


I'm leaning towards fuel , just because of the way it dies, and how it runs when it refires. Going to install, fuel pressure gauge, maybe try and run it off of a remote tank, ......if no luck , will probably replace fuel line from tank to pump...

thanks for the ideas

 

[Hedgehog]

Lets hope the site sign in problems are repaired some day soon. It certainly is frustrating for you new guys.

For some jeeps the start power circuit is different from the running circuit. Hit the starter and all power is turned off to all circuits except for the starter and the ignition. When the vehicle is running the key is set in the run position and that circuit gets power. At least that is how it works with some vehicles.

You probably don't need to replace your spark plug wires, just make sure they, especially the coil wire is seated well. I say that because your engine will run with a few spark plug wire removed, it won't run well, but it will run. With a coil wire problem nothing gets spark. Also, pull your distributor cap and spray WD-40 in the cap and the ignition itself. You could have some stray moisture in there that gets hot, turns to steam, condensates and scrambles the spark signal.

Because of the way your engine stalls, its an instant whole engine shut down, no partial problem that leaves cylinders sputtering, not even for a second. I'm leaning toward an electrical problem. You've done a lot and replaced a lot of parts, so what's left ... SP wires, your dist. body and one important thing your grounding wires, especially the grounding strap to your engine. It's got to be something like that. ..... Do the lights stutter or blink when the engine stalls? Your coil resister wire or circuit could be going bad. It gets hot, electricity stops flowing.

Many years ago my shop teacher said that one of the most difficult things to diagnose is whether it's a fuel problem or a spark problem. Both act in very similar ways. Over the years I've found that to be one of the most valuable pieces of mechanical advice he ever gave me.

 

[CJim7]

My money is on the Carb. My 84 was originally equipped with a Carter on a 4-banger and it used to do the exact same thing. It would run great and then acted like the fuel was abruptly cut off.

It's been over 20 years now so I cant remember what the exact problem was other than it was the carb....and probably something to do with it's interaction with the smog equipment.

 

[Hedgehog]

Okay Jim, what else should he replace? He's worked or replaces most of the fuel system other than the complete fuel line and the problem is actually worse.

Usually if its a fuel problem the engine won't instantly start right up. If it's electrical with an intermittent short or poor contact as soon as the contact is reestablished it will start right up and die when the contact is lost. I really am leaning toward a loose or corroded ground strap.

 

[jzak]

I agree with the others that a new Carb sounds like the best option. I had simular problems with my TBI unit. Changed just about every part of the fuel system, but the only thing that made any real difference was installing a rebuilt TBI unit.

 

[Lumpy Grits]

WELCOME
Is the smaller return line of the fuel filter at the 12 o'clock position. It MUST be positioned like that to maintain fuel flow/psi to the carb.
Are you still using the 'horseshoe' connector on the coil? They are well known for contact issues. I would have you switch to a ring terminal type coil and convert to ring terminals on the harness.
Is there fuel in the carb's bowel? When it dies-If you remove the top of the air-cleaner and look down inside the carb, work the throttle linkage. Do you see fuel squirting down the carb?
The other issue it could be is inside the IGN switch.
Clean/tighten the battery GND to the engine connection.
After you have check'd the other items I spoke of. Do this--
Run a jumper wire from the POS(+)side of the battery to the POS(+)side of the coil. Start it up and run for no more than 5-6 minutes(you'll 'fry' the coil). Does it keep run'n?
Post up what you learn.
LG

 

[Hedgehog]

:ww: Sorry, I jumped right into the question without welcoming you to the board.

 

[CJim7]

Okay Jim, what else should he replace? He's worked or replaces most of the fuel system other than the complete fuel line and the problem is actually worse.

Usually if its a fuel problem the engine won't instantly start right up. If it's electrical with an intermittent short or poor contact as soon as the contact is reestablished it will start right up and die when the contact is lost. I really am leaning toward a loose or corroded ground strap.

swapping carbs doesn't necessarily mean much...especially where Carters are concerned. If I recall, the power valve can be problematic with the BBD. If the carb runs out of fuel, the engine dies....sometimes pretty abruptly.

 

[Hedgehog]

Okay - multiple carbs reacting the very same way........... I hate to see a guy replace everything in a fuel system multiple times with no change in the original problem, without considering that it might be something else.

 

[CJim7]

Okay - multiple carbs reacting the very same way........... I hate to see a guy replace everything in a fuel system multiple times with no change in the original problem, without considering that it might be something else.

I agree. How much smog is on an 80 CJ? My carb failure was directly linked to all the smog garbage I had on my 84. It would just die.

 

[Lumpy Grits]

Well, I have to run all the SMOG here in PRK. Hasn't hurt the performance of my Carter at all.
Sounds like you had some sensor issues that gave the wrong info to your carb.
LG

 

[jdcaples]

Well, I have to run all the SMOG here in PRK. Hasn't hurt the performance of my Carter at all.
Sounds like you had some sensor issues that gave the wrong info to your carb.
LG

Is the ignition control module part of the emissions system? I only ask because I have a 1980 CJ7 Renegade and my ICM was (and remains) MIA when I took the title, as well as the smog pump, the carter carb and I forget what else came from the factory and is now probably in some land fill.
-Jon

 

[Hedgehog]

Yeah, the local guy I bought my CJ from was mighty proud of stripping all the emissions parts from the CJ until he found out that he had to put the stuff back on to register the CJ in Tucson. Oh man did he ever pull one over on "The Man."

 

[jdcaples]

Yeah, the local guy I bought my CJ from was mighty proud of stripping all the emissions parts from the CJ until he found out that he had to put the stuff back on to register the CJ in Tucson. Oh man did he ever pull one over on "The Man."

I'm fortunate that Washington State does not require emissions testing or inspections on vehicles over 25 years of age. I wouldn't know how to begin retrofitting that gear, esp the ICM if that's part of it.


-Jon