stymied?

I have a similar problem to "just ain't right". Mine however has me stumped. The problem started with what I thought was a dirty fuel filter. The motor would run fine and then cut out,sputter and then catch again. I installed a filter before the pump a couple of years ago because I have an old tank(another story). It was dirty and I thought problem solved. Right after that though problem got worse. It now runs along fine and then all of sudden it starts cutting out,popping, sputtering backfiring through the carb., and then bingo runs great again. Changed filter from pump to carb., inspected the filter and screen in the carb. Have done warm water tune(sprayed in carb). Nothing helps. Basically acts like bad gas but all of the family rigs get gas from the same place and none others affected. My other thought is that somehow goes out of timing and then goes back in or maybe something in carb. Any suggestions appreciated.

 

sounds like you have gas varnish loose in the carb and is clogging the jets.

 

i had the same problem, i have a 390cfm holly 4bbl. a cheap rebuild kit and an hour or so later and i never had the problem again. HTH

 

carb was just rebuilt 2 summers ago. Maybe stuff in jets. what about a fuel pump?

 

I was going to mention the fuel pump could be going bad.

 

diagnosing a problem like this can be frustrating.
appears to be fuel, but could also be electrical !
resist the urge to "shotgun" by throwing parts at it
I would disconect fuel lines/filter and blow thru them.
I would test fuel pump volume and flow; hose into a coke bottle works for me.
Rremove the top of the carb and take a looksey; clean/blow out if necc.
If all above check okay, then start looking at ignition possibilites; wiring connections, ballast resistor, coil wire, rotor, etc.
I think a good sit down/head scratchin will solve this problem.

 

I had the same problem and finally traced it to the fact that my underseat tank was for a four banger. I knew that when I installed it but figured it would not be a problem. When I swapped in a later CJ5 15 gallon tank on the rear, the problem went away. Check to see that you have the right tank for the engine. The four banger fuel outlet was 1/16" smaller than the one for the V6. It led to fuel starvation, and would recover after the engine quit and the fuel pressure equalized. Good Luck.

JK

 

Made sure all lines clear, checked fuel pump for volume-seemed ok. Cleaned carb with carb cleaner(just thru air intake). Noticed I have very little gas in my filter between tank and pump and seems to bubble some air in. Output filter fills ok but small air bubbles come in to it. I have had problems with tank before so I gues it is time to drop the tank and replace all the fuel lines(the supply line has been patched a few time it looks like). Next question- I have hard black plastic supply lines underneath the jeep Is this stock? Also I have what seems to be a shut-off valve or tank switch in the middle of the supply line but my factory manual shows nothing. Is this sock or PO thing. It is 71 and is supposed to have tank in back. The switch to me looks like my old 58 that had tanks under both front seats but with a key turn and not a handle turn. I have not ruled out fuel pump because I have had 2 already go bad because of crap in tank-might be pushing ok just not sucking very well(grammar?). Anyway going to drop tank,clean it replace old supply and return lines. While there I am also going to put in new poly body mounts I have been putting off for over a year.