View Full Version : Vapor lock
08-01-2010, 09:24 PM
Got bit by vapor lock today.Ran boat for about 30 minutes, parked on beach, It was realy hot today, tried firing boat up would not fire. I opened engine cover to let engine cool. I had heard of other people having this problem so Iknew exactly what it was. Let boat sit for aboout 15 minutes, still would not start. I pushed boat back into boathouse, it sat inside for 10 minutes in shade and stareted back up. Ran boat several more hours starting and stopping no problems. I have had this boat for four years, THIS IS THE ONLY HICCUP.Boat has almost 300 hours on it and still love it. HERE IS QUESTION, I heard people pour water on something when they get vapor lock,what and where do you pour water on? Keep in mind when i open up engine cover I am cluless. Boat is 2006 lsv 325 fuel injected assault engine,
08-01-2010, 09:58 PM
My understanding is people pour water on the fuel pump. From what I understand the fuel pump gets hot and when the fuel gets to the pump it vaporizes. So pouring water on the pump cools it down faster.
The fuel pump is located mounted to the motor closet to the drivers seat. It is a cylinder shaped item about the size of a coke can. Basically it has two metal lines coming out of the top of it and has a two wires coming out of it.
Indmar changed to two fuel pumps in 2008 because many owners have had problems with vaporlocking in 2007 and older models. You can contact Indmar and they will get you going to add the second fuel pump.
I have also heard that if you dont run the correct octane level (89 is recommended) this can make it happen more often. Some others also add a fuel additive which seems to help. Best bet is to get the second pump installed, from what I hear it not to difficult of a job.
Jim, I have an 06 OBV with the 325 motor that also had the same vapor lock issues. I am guessing that mine was from almost 5 years of E85 gas. Any way, I replaced the inline fuel filter with a new one and now run the blower anytime that I am under way or idling. After the fix I haven't had one problem regardless of whether I am surfing/ boarding or tubing the kids. The original fuel filter from SC was a CarQuest filter. I replaced it with a NAPA filter #3299 @ $13.00 from NAPA. There is only one filter on the '06/325s inline before and below the fuel pump on the bulk head. About a 5 min job with a nut driver. Took the old filter apart and it appeared to have some flake like sediment that looked too small to clog it, but who knows?
08-02-2010, 01:50 PM
The original fuel filter from SC was a CarQuest filter. I replaced it with a NAPA filter #3299 @ $13.00 from NAPA. There is only one filter on the '06/325s inline before and below the fuel pump on the bulk head. About a 5 min job with a nut driver. Took the old filter apart and it appeared to have some flake like sediment that looked too small to clog it, but who knows?
This just worked for me last weekend. After 300 hours, the OP's boat is overdue for a filter replacement, even if vapour-lock is the immediate problem.
08-16-2010, 09:01 PM
I have a 2007 LSV with the 325 Assault motor and the frequency of the vapor lock has increased to about 50% of the time on the water. I spoke to Indmar and they do have the secondary pump available but it is almost $300 just for the parts! I love my boat but would like to avoid spending the money on something that seems to be isolated to the Moomba's. My friend with a Malibu Sunsetter of the same vintage has no problems with his ever.
I note that for 2011 Moomba is advertised as having an "in the fuel tank pump" so they must be aware of the problem. Does anyone know of any fix or service bulletin from Moomba regarding this problem?
Indmar said something about installing an insulating spacer between the pump mount and the engine block so that the retained heat of the block does not heat up the fuel pump. Has anybody tried this?
08-17-2010, 07:44 AM
I also got bit for the 1st time in my 05 LSV 325 FI this weekend. Very hot, humid day. Boat ran fine till we pulled in the covered dock for a break. Then it would start and die. Didn't hear the fuel pump run when turnning the key on. Took a cold bottle of water out of the cooler and poured it over the fuel pump, turned the key on and heard fuel moving. Ran fine the rest of the day but I kept the blower running.
08-17-2010, 10:49 AM
On hot days, I keep the blower running all the time the engine is running and for a few minute after we shut down. If convenient I will also open the engine cover for a few minutes as soon as we stop to let the hot air escape. I have not been bit yet. Of course, here in the NW we don't get that many really hot days.
08-17-2010, 12:13 PM
if you keep your blower running on hot days, or on warm days and you run the engine at high rpm's vapor lock will not happen. octane doesn't matter, it's all based on ethanol in the gas. if you can get non-ethanol gas, issue will go away, or if you run an additive like star-tron. if you do get stranded, the quick fix is to dump a bottle of water on top of the fuel pump, as someone said right next to the engine. that will cool it down enough to allow the fuel to return to a liquid and flow again. ethanol-blended fuel has a much lower boiling point than regular gas. it's also a good idea to keep your fuel filter changed regularly as ethanol has a habit of picking up sediment and water and pulling it along for the ride..
you can spend the $300 for the added fuel pump, but if you just run your blower all the time on hot days or when running the engine hard, the issue should not materialize again...
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