Scenario:

Replaced "bad" carb, the one that I couldn't get to idle... with supposedly "good" carb. Starts and idles fine now with good fuel flow, choke is working correctly, all wires hooked up where they're supposed to be, vac lines plugged up, etc.

Problem: Fuel just cuts off suddenly after about 5 mins. of normal driving and the engine dies. Pumping the gas doesn't help, it just makes a sucking sound. Won't start again unless it sits for a few minutes. Drives OK for another few minutes and dies again, same thing.

Took it to a local shop and they basically told me I needed a new carb, as "we don't rebuild 'em anymore." (Okay, thanks a bunch.)

Anyway... It's NOT the fuel filter or lines (they're new), and the pump is working ok. The idle speed and mixture screws are adjusted properly AFAIK.

Any notions as to what this could be? I thought it might be the fuel cutoff solenoid... Something could be screwed up with it or it's getting power when it's not supposed to? Any way I can test it? Maybe a float or jet problem?

It's gotta be something simple... I hope. Any suggestions or ideas would help.

Thanx....... MM

 

sounds like when a BVSV is opening it's causing a vacuum leak from somewhere, once it cools down it "closes" therefore no vacuum leak. that sucking sound you hear somewhat backs up a vacuum leak.

Also make sure you have the vacuum lines hooked correctly and not backwards on the distributor as well.

BTW as long as the ignition switch is on the idle shutoff solenoid is supposed to have power. I don't know why so many people have this confused with something that gets intermittent power based on engine temp. Power keeps the solenoid open so fuel can flow through it. The purpose of this solenoid is so the engine does not get residual fuel pressure into the engine when the ignition is turned off causing it to diesel. Which is why it closes when no power is applied to it.

 

Maybe some old fuel line that collapses under suction? Had this problem on a 67 LeMans I owned. Would idle all day long, but try to do any driving and the fuel line would collapse cutting off fuel to the carb and kill the engine. I know you said you checked the fuel line, but on my LeMans the fuel line that was collapsing was brand new, so it's still a possibility.

 

Ok, so I played around with the fuel lines... no changes.

Also found the BVSV vacuum & sensor thing on the coolant line. Anyone know how to properly bypass this BVSV thing? I just tried removing and plugging up the lines, and I'm still getting the same result... Idling OK, you can rev it up a few times, and then it dies as if it's losing fuel.

???

 

Can you see the fuel level in the carb at idle? maybe the float is sticking or is not adjusted properly. You 100% sure you have the fuel lines hooked up correctly and not backwards on 1 or 2 of them?

did you check and make sure you have the distributor lines hooked up correctly on both ends of the vacuum rail for the distributor?

 

Success!

Replaced the fuel input line from the pump to the carb with a clear line so I could tell for sure if the gas was getting there or getting cut off. It wasn't.

So, after spending nearly all day removing and re-arranging wires and vacuum lines, restarting, revving, and seeing what happened.... It turned out to be the BVSV thing, it's bad, I guess. I tried bypassing it by plugging the switch off and running the two vac lines from the rail to some unused constant-vac ports. I'm not sure what those two lines went to, but, hey, it works.

It stays running now - it was cutting out after maybe 30/40 seconds of running at any higher rpm than idle.

God, what a frustrating ordeal. I need a Weber. And a beer.

Thanx for the help... MM