I believe I have a vacuum leak in my 400, as when the choke disengages it stalls.

So I have taken a propane torch unlit along the vacuum lines and saw no change in rpms, plan on doing the same around the intake and carb tomorrow, choke disengaged so I figured I'd look at it tomorrow.

Any other suggestions for places to look?

 

sounds to me like you are not getting enough fuel when the choke opens and to much air

 

That's exactly what I think is happening and was told that it's called a vacuum leak, unless there is another cause for that.

I have been testing it with the air cleaner on and everything else buttoned up, so I don't know what else it could be.

 

do you have a way to see what your fuel pressure is at the carb , what carb do you have on it and is all clean ? what about your fuel filter also, just a few things i would check

 

Challenger, I did buy a fuel filter so I can change it, but forgot until you just mentioned it. What would I need to be able to check the fuel pressure? I sprayed some carb cleaner in it and the back two barrels have no change when I sprayed into it, but the front two would cause the engine to change rpms when I sprayed into them.

Doc, with the choke on full I don't think so, but I do not know how much noise a vacuum leak makes, or what it sounds like, so maybe I can and have been hearing it.

 

Is that just if its leaking through the hoses, or anywhere. Will try to listen for that when I run it next.

 

Ok thanks Doc, the engine won't even idle as soon as the choke disengages the engine sputters and stalls.

 

I could drive it as long as I don't touch the accelerator which disengages the choke. Not sure how fast.

 

commando it seems to me that your carb is not set right even with alittle vacuum leak it should still run, can you still be giving it gas when the choke is off and still runs or doed it just shut down completly , is the power booster line off or it could be your booster is bad i would also check that .... dont really remember to much about the 400's but does yours have the box mess on the air breather maybe some one might know what its called but those gave alot of problems back in the days , if you have the breather off and stomp on it do you hear alot of vacuum in the carb ?

 

No the lean burn is long gone, I have an Edelbrock carb on there now, that had been running for awhile, but the car sat for a few months, then started having this problem. I treated the gas and sprayed carb cleaner in there on Saturday. Will be changing the fuel filter when I get a chance.

I can keep the engine running, but I have to push down a good amount on the accelerator.

I do not know what the power booster is, maybe if I saw it I would know it. But all the lines are connected.

Haven't pulled the breather off and tried that, but I will.

 

Chally, do you mean the thing the master cylinder hooks up to?

 

If that's it would I see a problem with the brakes? As after the choke disengages and I have my right foot on the accelerator, my left foot is on the brake so I don't go through the wall when I put the car back in the garage.

Could it just be the valve?

 

Ok, I think I figured it out, a friend of mine said I could determine if it was the booster or not by blocking the line, no change, so I crimped the line from the PCV valve and think that unclogged it or something as it now idles. I cleaned it out with some cleaner and am going to grab a backup tomorrow and see if it runs better.

Chally, I appreciate you suggesting the booster as I would not have found it, and I found a master cylinder lying around in my friend's store, so I will be replacing the rusty thing in there now, with a nice clean one. He didn't have a power brake booster, which is fine as I would have bought one and not needed it, but did get a good deal on the MC.

 

Hey commando i hope you found the problem and i guess i should of told you to make sure your pvc was clean and rattles but bad me hehehehe hope all is good

 

All should be good now, as I thought I was having cooling issues as well, but that's from running the engine at full choke while I was looking for the leak.