help with stalling sometime and diesel ing at deceleration (1 Viewer)

[rfwj]

I have a 60 de smog ed. aftermarket foreign stock carb. It Runs and idles ok 700 rpm when i start it. no choke. then drive a bit and come to a stop and it stalls to zero rpm. Like it is getting no gas or vacuum leak. I pull choke and start and then runs ok and i push the choke in. it runs for a mile or so. then it happens again at next stop light. Like and intermittent vacuum leak or it is not getting gas? I do think the manifold gasket is old and might leak a bit. Also when coasting in gear with foot off gas running at 2000 rmp it seems to diesel or back fire slightly.

things i have done:
new fuel filter
new plugs and wires
cap and rotor
new fuel pump

So i believe I am getting gas to the carb and getting a spark fine.

I do not understand how it can idle ok with no choke. then all the sudden after driving I need the choke to keep idle. then go back to normal at the next stop light?

Thoughts? new manifold gasket. carb clogged. float? but why would it work sometimes at idle?

It is a good OME Carb. Not the cheap replacements. City Racer made in japan

thanks and sorry for the long post.

rich

 

[OSS]

Connect a vacuum tube to the manifold and run it back to the cab so you can see it all the time while driving.
You’ll then be able to spot if the problem iis some weird vacuum leak when the engine stalls.

Remember- when the engine is warm, the choke knob no longer acts as a choke. It’s simply a throttle positioner. No different than pressing down on the gas pedal a little.

 

[rfwj]

good point on the choke while running. it is like it looses idle or no gas at one stop light. then gains it back at the next stop light. I do think it is something in the carb? it was supposed to a be a good Japan made one. worked great until now.

 

[Pighead]

When was the last thorough tune-up?

 

[Spike Strip]

Sounds like you may have schumtz in the idle circuit or a malfunctioning Idle control valve or circuit.