Idle problem

[Rodney Bullock]

What would make a car not want to idle in drive? When I first built the stude it idled great as time goes on it will not idle in drive. Today I wanted to go to a cruz in and the car acted up so bad I had to take it back home. I have checked for a leak at the manifold and the carb base. It will run fine for a while than at a stop light or sign it will act like it want s to cut off. I wonder if the fuel pump is going bad would this cause such a problem? I looked at the fuel bowl when the car cut off and it was empty.

[JerseyHarold]

If the automatic trans has a vacuum modulator that could be leaking and causing your problem.

[Rodney Bullock]

Those Borg/warner flight-o-matics did not have a modulator. I think my problem is spark plugs, I pulled one this morning and it was sooted badly. I think they are washed. I cleaned all of them and the car ran great for a while then went back torunning bad after an hour. I think I had this problem long ago in a mopar v8 I had. The car ran great for the first few weeks however the idle quality got worst and worst until it would not run well at all.

[Phil Martin]

If the fuel bowl was empty it has to be a fuel system problem.

[RFleetwood]

a quick way to check for vacuum leaks.

spray carb cleaner on the suspected area whether this be hose attatchment or manifold seal with the car running.

If the idle increases this is youre vacuum leak.

that is were I would start.

[JerseyHarold]

Soot= rich mixture

A vacuum leak would allow excess air, making it run too lean.

You may want to tap on the carb while the engine is running to see if it helps. If it runs smoother, it could be a sticking float keeping the needle valve open and allowing too much gas.