running poorly - F-head

The problem happened suddenly - the Jeep was running great - lotsa power, good throttle response - it was AWESOME!!
Then it died after idling in the driveway for 15 minutes - so far, nothing I have done has changed the way it is running.....I could have sworn it was fuel related, but carb, filter, plugs, distributor cap, and fuel pump replacement have had absolutely no effect - good or bad.
Anyone know a good psychic? or an Exorcist?

 

replaced the plugs in an attempt to solve this problem - same time as I swapped the carb and fuel filter - Jeep started slightly quicker, but still has no power.

 

Have the coil, have not had time in the garage to install it yet - the spark plugs I took out are NGK's the number crosses directly to the J8C. Temperature seemed normal, but I have not run it very long since it died in the driveway.

 

Just for the hell of it check the carb. to see if the float's needle seat has backed out. IF your runnin the carter carb. Two weeks after a rebuild, I had the float valve needle seat loosen on mine and effectively lower the fuel level in the bowl progressively to the point where it would not even idle, but acted exactly like your describing. Don't care if the carb is new, it can happen.

Just a hail mary but.........

 

Installed the coil - NO CHANGE -
I'm ready to put a bullet in this thing.

 

That's the next step - yank the distributor and swap back to points - but I'm gonna probably just let it sit for a week or so - I'm still mad at it and I don't want to break anything.....

 

Good plan. Take a breather and come back when you are fresh.

Any chance it could have "jumped timing" on the cam gears?

Time to call an exorcist?

Pete

 

Have been actively watching this thread because I have simular issues with a CJ6 jeep. Gave up on it about 6 months ago and just assumed that the engine would require a rebuild. (smokes a little but not really that bad..)

Some of my obversations/replaced items:
1) new solex carb/fuel pump/fuel presure regulator
2) Did notice that if I cliped a timing light over the various wires as it was running that the spark was very erratic on some cyls. (changed points, condenser, coil, plugs/wires same result..) Was going to order a new distributor but I quit at that point.

(Do you have a timming light that you can clip on the various wires quickly to see if you have erratic spark on some cyls??)

3) Jeep would start when it was cold and as the engine warmed up it lost all power.
4) compression was good across all 4 cly (if i remember correctly about 120 across all cyls).

Understand and feel your pain/fustration will continue to monitor.

Howard

 

How long back was your 12v conversion?
could the balast resistor have gone bad?

That is one little Item I know nothing about, and would be interested to know if that would cause the problem.

:hurrican: Also, just went out and tried to start my old beasty, and it fired and ran for about 45 seconds then died. I cranked a while then started checking things like fuel spurting when the accelerator is pressed and like that. Nope! Checked the little see-through fuel filter I have installed before the pump and it was dry, checked the tank and it was dry also. Could a sworn I had a quarter tank yesterday when I took it out, but could be wrong. Gallon and a half and she fired right up.R)

Knew a guy around here that went out and kicked and kicked and kicked on his kick start motorcycle. He KNEW he had gas! Turned out his wife was going out and riding it when he wasn't home and didn't fill it up again when she was done.

Could be?

 

Threw 3 gallons of gas in it before I started swapping parts.
All in all, it has been running for maybe 25 minutes total since this problem started.
After swapping in the pertronix coil, it started fine, but will not rev up well. If I open the throttle to accelerate, the engine bogs and kinda chokes and then just stalls.
If I hold the throttle at 1/4 or more, the engine will not stay running - the rpm's do increase, but it will not maintain anything faster than just above idle.
Haven't been back out to it yet, still mad.

 

That still sounds a lot like a vacuum leak...

Pete

 

17" of vacuum at idle - steady as a rock.