VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1929-1932 Vapor lock...?

I think I might have encountered my first experience with vapor lock. I took the '32 out for an errand cruise with my 11 year old son this Saturday, which was a pretty warm day here in upstate NY. We stopped at the hardware store, and when I tried to start it up, nothing would catch, even with a couple of spritzes with a can of instant start. It would crank and crank, but nary a spark. Well, we had to walk home the two miles, so we did some character building and good exercise. I got a ride back to the car in about an hour, and I was able to fire her right back up again, as if she said "What starting problem?"

I took a look into a restoration book that I've referenced in the past about avoiding vapor lock. One of the tips was to put in an electric fuel pump underneath the rear fender, which I did a few years back when I was rebuilding everything. The advice said that the pump will help for faster cold starts after a long period of sitting, and help "overcome" vapor lock. I've since switched the electric pump on before starting, and it does seem to help. Tonight I also put an insulation gasket below the carb to help avoid the problem. (I had it hanging around, but I didn't think I really was going to need it... ...)

My question is, then, does this little incident seem to be the tell tale sign of vapor lock? And if so, is there any tip or trick about any quick curbside diagnosis and/or fix if I run into this again? For example, I wonder if running the electric fuel pump for about 10~15 seconds before starting helps to push out this vaporized gasoline.

If you did not have any spark then it was not vapor lock. I would suspect condensor or coil or ignition switch in that order. Could also be moisture in distributor, crack in cap or several other ignition related problems. Lack of spark does not have anything to do with the fuel system.

You know, you're right, and I should be careful with terms. I was getting "spark" from the ignition - I meant I couldn't get any semblance of the engine firing up. The entire ignition system is 3 years old with about 78 miles on it. Every subsequent start I've had since then is quick and easy.

You indicate the entire ignition system is "3 years old and has 78 miles on it", if I read that right you are driving about 25 miles a year and one of the problems could easily be a combination of heat and old gasoline.

The fact that starting fluid did not get the engine started suggests over fueling or flooding and not vapor lock. Vapor lock is an under fueling that should have been overcome by the use of starting fluid.

Do you have the original '32 carburetor or a later replacement? If the original, it has a tendency to flood the manifold with gas when shut-off. Hot weather will accelerate the syphoning of gas from the fuel bowl past the low speed jet into the manifold. If that is the case, when shut-off it will take 15-30 minutes to clear the extra gas so a proper mixture is taken into the cylinders. Other W-1 carbs also have a tendency to flood but not nearly as much as the '32s and '33s. Lowering the float level will reduce the problem in all W-1 carbs.

Chipper -

Gee, that's a great diagnosis. It happened again last night, and it really does feel like a fuel problem. The carb is a W-1 rebuilt by the expert hands of the ol' Junkyard Dog.

Glyn, not to bypass your thoughts - yeah, it's been a modest amount of neighborhood putt-putting around. I do try to run down the gas tank to a small amount before winter, and I dump a can of winter fuel stabilizer in when she's retired for the winter. I'll agree that it doesn't help to have "matured" gas in the tank (it doesn't improve in age like wine or whiskey).

In particular to the float suggestion...as I mentioned, I've experimented this weekend with running the electric fuel pump before starting. Last night that seemed to be the trick to get it started. Am I just making a false connection, or could there be something to the increased pressure pushing the float closed and getting the manifold to clear?

Now, if I take off the carb and pull open the top to get to the float, is it just a matter of pushing the float stop slightly higher, like 1 mm or 1/32""?

I've topped off my radiator for whatever incremental cooling that will contribute towards the problem, and I'll change out the fuel filter just as another doublecheck.

How much should I tweak the float?

Ed Smyth,
I would suggest filling the gas tank and adding fuel stabilizer for winter storage. If the tank is full you will have less chance of condensation forming and rusting your tank.
Dan.

Good point. I do pour in fuel stabilizer in the winter, but the condensation issue is a good one to consider as well.

Skipper sent me a private note, and after a couple of exchanges he felt that the two fuel filters I had on my system was one too many. Sooo, this morning I went underneath and pulled off the fuel filter mounted behind the electric fuel pump. Between that and the insulation gasket for the carb I think I shaved off some level of risk on a repeat performance. Tomorrow morning looks good for another test run.