85 CJ7 weber help with rough idle

[amc75matador]

yes, this is my first post, I've been looking for help on troubleshooting this Weber for a couple of days, and it's led me here, I have searched posts here and all over the internet, I figured I'd ask the question and post some links to vids of the thing running, see what you guys have to offer, I just picked this up and all I know it the BBD was bad, leaking at throttle shaft, imagine that!, and PO replaced with weber 32/36, in the process of trying to get it running a ign coil, fuel pump and fuel filter were added, after failed attemps it sat for a while til I grabbed it, with a makeshift fuel bottle plumbed to the fuel pump and a couple squirts of carb cleaner, it fired right up, now once it's idling it stays running and will drive down the road and I can get into all gears (5spd) and shows plenty of pep, just has that DAMNED rough idle that I'd like to cure, I will try to post links to videos i just uploaded to youtube but I am not great at this,
85 CJ7 AMC 258 i6 / 4.2l , 5speed, manual brakes and no power steering
cold start attempt 1 - YouTube
cold start attempt 2 and 3 - YouTube
idle cold start - YouTube
idle at tach - YouTube
rough idle after 5 minutes - YouTube
weber rough idle close-up - YouTube
weber rough accel decel - YouTube
weber accel decel shutdown and restart - YouTube

 

[rlitavecz]

Check the fuel pressure. Weber carb can handle a max of 3.5 PSI. Most fuel pumps exceed this! Run a holley red regulator ahead of the carb.

 

[mrspacemonkey]

I have seen lots of people install a fuel pressure gauge along with a fuel regulator. If the regulator is pre set, do you need a pressure gauge? Wonder if this is personal preference or good practice to monitor pressure?

 

[amc75matador]

Check the fuel pressure. Weber carb can handle a max of 3.5 PSI. Most fuel pumps exceed this! Run a holley red regulator ahead of the carb.

I havent checked the actual pressure, but there was a restrictor (installed backwards no less) inside the fuel return line going back to tank which I removed, I ran the return hose back to the rigged fuel can underhood and I notice that there is a steady flow, I dont think there is much pressure now but I have not put a gauge on it, also removing the restrictor did not make any difference in the way it runs.

I noticed something else today while doing a vacuum check, I get 22 inches of vacuum while idling, however when I unplugged the gauge to cap the fitting the idle kicked up quite a bit, as if the engine is running too rich. Later I discovered a broken vacuum line going to distributor advance and upon fixing that the engine stalled. i am guessing it is running way rich and needs all the air it can get???

 

[rlitavecz]

I havent checked the actual pressure, but there was a restrictor (installed backwards no less) inside the fuel return line going back to tank which I removed, I ran the return hose back to the rigged fuel can underhood and I notice that there is a steady flow, I dont think there is much pressure now but I have not put a gauge on it, also removing the restrictor did not make any difference in the way it runs.

I noticed something else today while doing a vacuum check, I get 22 inches of vacuum while idling, however when I unplugged the gauge to cap the fitting the idle kicked up quite a bit, as if the engine is running too rich. Later I discovered a broken vacuum line going to distributor advance and upon fixing that the engine stalled. i am guessing it is running way rich and needs all the air it can get???

Your fuel pump can put out 9-10 PSI and will overpressure the float valve on the carb causing a rich condition. I would check the fuel pressure.

 

[amc75matador]

Ok guys, thanks for the help, I had some time to play with the jeep and got it running great, it turned out to be a combination of things, idle mixture too rich, timing off, no choke operation, vacuum leaks, idle screw cranked way up, here are some clips, everyone loves clips
85 jeep cj7 weber smooth idle tuned - YouTube85 cj7 weber running rough - YouTube85 jeep cj7 idling at tach - YouTube