View Full Version : vapor lock again

07-13-2009, 08:30 AM
first time since early last year.
ran somewhat hard for 10 minutes, then shut her down and drifted for around 1.5 hrs. probably should have had the blower on for a while, but didn't.. went to start her up. she sputtered and would not engage in gear without dying. temp was only 90 and humidity was around 15%, so not a real hot day. sun was in/out of clouds all day.

took a bottle of water out of the cooler, poured about 1/2 on the fuel pump and she took of without missing another beat...

think I might add the in-line pump this winter..

07-13-2009, 08:52 AM
Man I feel for ya. I just went through this and luckily it was just the fuel from the end of the last season. It was the winter blend that vaporized too easily. I put in seafoam and 91 octane, and no more problems. I also took out the carpeted board behind the rear seat and leave it open about an inch to get more air flow to the motor compartment. I am thinking about installing another fan at the top of the motor compartment since the blower that is in there is at the bottom and really doesn't pull any heat out, just vapors in the bilge. I have an accessory switch that is unused, so that is where I will wire it too. Good luck.

07-13-2009, 09:33 AM
yikes- that doesn't sound like fun. Can you explain to this newbie why this happens and how to prevent it?

07-13-2009, 10:47 AM
ethanol blended fuel has a lower boiling point than regular gas. when the engine compartment is hot and no fuel is flowing, the gas "vaporizes" and creates gaps in the line. the engine won't get enough fuel to run, just idle poorly. as soon as you put it into gear or add any load, it idles down and usually shuts off.

couple solutions are to add an inline fuel pump right after the tank ahead of the fuel filter. this adds more pressure to the line and pushed the vapor lock out.
pour water over the fuel pump. usually fixes the issue, but hokey.
run the blower more often and longer pulls heat out. good fix mentioned above for an additional fan.
most of the boats that don't have in-tank pumps are experiencing the same issues. I have heard mastercraft, malibu and skiers all have issues with it.

07-13-2009, 06:25 PM
It was/is a poor choice to put the fuel pump right next to the engine. Engine heat will soak into the metal of the pump. Most boats/cars/planes locate the pump away from heat.
After running your boat for a while and you stop, open your engine cover for a few minutes and/or run your blower to circulate cooler air. This will help limit vapor lock.

If the pump fails, however, it is very easy to access. So there is something good about it.