Vaporlock ??

[Riggs]

In the last few weeks I have been having trouble with my 13 HP Honda engine on my Norwood dying in mid cut. At first I thought that I had got some trash or water in my fuel. I removed the tank, cleaned it out and I am now double straining any gas I put in. Saturday was more of the same, It would run fine, then start acting like it was starving for gas, then die. Once when it started I thought it may be close to running out so I took the gas cap off to check with the engine running, or trying to. As soon as I took the cap off, it cleared right up and ran fine. The next time it started to sputter, I did it again, again it cleared right up. I finally  just started loosening the cap after every couple of passes, and had no more issues.


I am a long ways from being a decent mechanic, but is this vaporlock? If not what could be causing this? What can I do to keep from having to constantly having to loosen the cap?


Thanks for any input.

[Al_Smith]

You don't have actual vapor lock .What it sounds more  like is a blocked vent in the cap or where ever else the tank vents to .

Actual vapor lock is where for example the fuel line leading to carb runs in such a way the gas becomes vaporized within the line and thus no gasoline in it's liquid form can get to the carb .

Examples of same where quite a problem on the old Ford Y block series such as the 272,292 and 312 engines where the cross over pipe for the exhaust manifolds ran right next to the steel fuel line .The heat blown back on the engine from the fan would heat the line up .

The old shade tree mechanic cure was attaching about a dozen clip type clothes pins to the line which acted like heat sinks absorbing the heat away from the line .Sounds silly but it worked .Another is covering the line with layers of aluminum foil .--junk yard dog trivia 101 ---

[Chuck White]

I would bet that the vent in the gas cap is plugged or otherwise closed as Al said previously.

Been there, done that, forgot to open the vent.  :

[Riggs]

I can blow through the vent on the gas cap, could it be sealing itself once it is screwed on?

[Al_Smith]

 :D It used to be an old trick on the Briggs engines that had a little hole in the cap for a vent .You pull the gasket out and jam the hole full of chewing gum blocking the vent ,put the gasket back .Usually the trick was played on your buddy with a mini bike .Ornery kids from the 60's . :D

[shelbycharger400]

could be vaporlock.  I switched back to "good" gas on all my small engines.
Most of the ghost issues dissapeared

[Tree Killer]

My John Deere did that to me this summer, I Googled it lol and found that the lil hole in the gas cap was plugged. Cleaned it out & it was fixed.  good luck

[Magicman]

My Honda generator did it to me during hurricane Isaac, or maybe I did it to myself.  I forgot to open the vent on the gas cap.  It will not run with it closed, not for long anyway.