We have had a few customers call and tell us about a few vapor locking issues that are occuring so we thought we would put an alert out to explain what is going on and what can be done to keep this from happening. Keep in mind, this is not just a Supra/Moomba thing. All boat manufacturers are fighting this problem.
Just this year, gas with ethanol is being introduced into our area gas stations. Unfortunately this is causing some problems in some instances with a problem called vapor locking. Most instances where we see this is if the engine (most of the time it is the 340 hp ETX/CAT engine) has been running hard for a good while and then is turned off for 30-45 minutes. When the boat is cranked again it will sometimes not crank or start, then run rough and die. This happens because when you introduce ethanol in gas, it lowers the boiling point of gas quite a bit. When the engine is turned off, all of the heat from the engine is kept confined in the engine compartment. This essentially boils the gas in the fuel lines and fuel filter. When the boat tries to re-start, fumes are fed through the engine and it will not start at first.
All boat and engine manufacturers are working together with the National Marine Manufacturers Association (to stay under NMMA regulations) to find a remedy to this problem. In the meantime, there are a few things that you as a boater can do to keep vapor lock from occuring. First, keep your fuel filter changed. Indmar and Skiers Choice recommends changing the filter every 50 hours now, not 100 as stated in the owners manual. Second, run your blower more often. Many times we will run the blower the entire time that the boat is on the water. This will keep the air circulating in the engine compartment and bilge area. Third, if you have been running your boat and decide to stop and swim for a bit, open the engine compartment to let the engine compartment cool off.
If vapor locking happens to occur it is not the end of the world and normally will not require a service. First, open your engine hatch to let your engine cool off. After 15-20 minutes the engine should be cool enough to start and run fine. If you do not have time to let the engine cool there are a few more things you can try. First, open the engine hatch. Grab a towel and get it wet or get a cup of water. Put the towel against the fuel pump or pour a little water on the fuel pump so that it will cool down. Turn the key on and off to the run position a few times and then try to start. If this does not work the first time, repeat and try again.
We will keep you upadated as a fix for this problem should be in the works. Until then, just a few simple changes in your boating habits will keep you happy on the water.