Does vapor lock really happen?

[DaveM]

Sorry for this being a bit wordy. But I always thought that vapor lock was something tossed out when there was seemingly no easy explanation for an engine to stall. Perhaps it is real?

Here's what happened...

Launch the boat and cruise 35 minutes (or so) across the lake loaded with stuff to spend the weekend. Unload, set up the tents (took about an hour), then head back out to join others on the lake. By this time the outside temp has climbed to 111 in the shade. We sit for at least an hour enjoying everyone's company, then push off to do some skiing. I only went about 200 feet out before the engine suddenly dies and refused to start.

And what I did...

Could see something squirting in the carb, presumed it was gas. Pulled the #1 spark plug and saw spark. I get towed in and let the boat sit until the next day and try again when everything has cooled down. But still no go. The engine cranked, but does not fire at all. I removed the fuel filter and notice it is half full. I did not try starting it until I could get a second opinion. He can see/smell gas squirting into the carburetor. I again try cranking it over and it fires right up and runs like a champ.

Boat specifics...
1994 Wellcraft Excel, Volvo Penta 4.3L V6 2 bbl carb
replaced: anti-siphon valve (2002) fuel pump (2004) coil (2005) filters (every season)

Questions?
1. How common is vapor lock?
2. Why only me and not the other boaters I was with?
3. Could this have been prevented?
4. Is there a quick fix once this happens?

 

[Fun Times]

Re: Does vapor lock really happen?

Sorry for this being a bit wordy. But I always thought that vapor lock was something tossed out when there was seemingly no easy explanation for an engine to stall. Perhaps it is real?

Here's what happened...

Launch the boat and cruise 35 minutes (or so) across the lake loaded with stuff to spend the weekend. Unload, set up the tents (took about an hour), then head back out to join others on the lake. By this time the outside temp has climbed to 111 in the shade. We sit for at least an hour enjoying everyone's company, then push off to do some skiing. I only went about 200 feet out before the engine suddenly dies and refused to start.

And what I did...

Could see something squirting in the carb, presumed it was gas. Pulled the #1 spark plug and saw spark. I get towed in and let the boat sit until the next day and try again when everything has cooled down. But still no go. The engine cranked, but does not fire at all. I removed the fuel filter and notice it is half full. I did not try starting it until I could get a second opinion. He can see/smell gas squirting into the carburetor. I again try cranking it over and it fires right up and runs like a champ.

Boat specifics...
1994 Wellcraft Excel, Volvo Penta 4.3L V6 2 bbl carb
replaced: anti-siphon valve (2002) fuel pump (2004) coil (2005) filters (every season)

Questions?
1. How common is vapor lock?
2. Why only me and not the other boaters I was with?
3. Could this have been prevented?
4. Is there a quick fix once this happens?

Because the engine sat for a long time [the next day] and it still did not start, It sounds more like the engine was flooded with fuel then vapor lock. Try pulling a few spark plugs to see if they look rich at all. You might have a blown power valve, Or the needle and seat may have got stuck and flooded the engine. The quick try for a fix would be to leave the throttle all the way open for say 10min or so then try to start it with it still open then slowly pull up on the handle while cranking. Then you might need to give it about 1/4 more throttle and fuel to get it started.Try not to pump it a lot. When you found the filter almost empty did YOU refill the filter back up and then it started? or did you leave it low?

 

[DaveM]

Re: Does vapor lock really happen?

Because the engine sat for a long time [the next day] and it still did not start, It sounds more like the engine was flooded with fuel then vapor lock. Try pulling a few spark plugs to see if they look rich at all. You might have a blown power valve, Or the needle and seat may have got stuck and flooded the engine. The quick try for a fix would be to leave the throttle all the way open for say 10min or so then try to start it with it still open then slowly pull up on the handle while cranking. Then you might need to give it about 1/4 more throttle and fuel to get it started.Try not to pump it a lot. When you found the filter almost empty did YOU refill the filter back up and then it started? or did you leave it low?

I pulled only the #1 plug and it looked normal--dry, light gray electrode. I didn't really pump it too much while cranking. I left the fuel filter low and it later started like there was never a problem.

If this really was vapor lock, then the problem fixed itself. But I keep wondering what could be done to keep this from happening again...?