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Engine cuts out while driving at speed

RandyLL

1 Long CJ
City
Highland
State
IL
At highway speeds, my engine seems to cut out completely then comes back. Intermittantly and some days worse than others. It has newer fuel tank, new fuel lines, filter, etc. I've swapped ignition module, coil, wires, cap, rotor, starter relay (I had one short out internally), etc. I know I've got some carb issues, because it also dies (sometimes) when I come to a stop. My question is, could there be an issue with the ignition switch (key). Does the igni.mod/coil power actually run through the switch? I was thinking I could run some sort of bypass wire to check this theory.
I do plan on rebuilding the carb and I am also considering an HEI system.
 

walkerhoundvm

Just trying to stay upright
Lifetime Member
City
Cave Creek
State
AZ
Sounds like you've already tried most of the things I would've. How are your vacuum lines, namely the vacuum advance and PCV/canister lines? How's your timing? Hmm...fuel pump? Carb rebuild/tune would be next on the list, you're right, but that cutting out and coming back sounds sorta like electrical.
 

RandyLL

1 Long CJ
City
Highland
State
IL
The fuel pump has been replaced. It accelerates fine at lower speeds. I mostly notice it at highway speeds above 55 (5th gear, RPMs around 2k). In other gears, at lower speeds, I have to really get on it for it to cut out. Probably not hitting the higher RPMs at long intervals like when I'm on the highway.
 

surfjeepzx

CJ-8 Member
Gold Member
Member
City
Wilbur by the Sea
State
FL
The next thing I would go for is the ignition switch. Not the key assembly. The key is a lock assembly that rotates and push/pulls a switch that's attached along the column just past the dash panel. It's mounted on the top of the column. They are not expensive so buy a new one instead of messing with used electrical parts.
 

mysunnshine

Legacy Registered User
City
Phoenix
State
AZ
Tape a timing light on the hood and go for a drive. When it starts to die, have somebody watch to see if the timing light stops flashing. That way at least you can narrow it down to either fuel or spark. I'd put a fuel pressure guage on it too just to watch the pressures too.
 
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