Help possible vapor lock????
 

I have a 1999 330 SS (7.4MPI'S) and I ran over to Long Island yesterday and the boat ran fine no issues or anything, on the way home the boat started up fine and ran perfect, I got to the end of the no wake zone and it started off fine got going and then the tahc started surging and then I lost power and it would die down to like 800 RPM's....then stall. I would shut it down and then I could get a blast out of both motors for 20 seconds and then it would do the same thing. The other motor ran fine, I then swaped the fuel filter from one motor to the other to see if it would make a difference, then neither motor started, I got in there and cranked the filter tighter and the bad motor that wasn't running before now ran perfect and I couldn't start the good motor. Is this vapor Lock??? Any suggestions would be appreciated. Thanks in advance.

Re: Help possible vapor lock????
 

That sure sounds like vapor lock to me.

Re: Help possible vapor lock????
 

What do I have to do to fix it or will it be fine next time I go to run the boat?

Re: Help possible vapor lock????
 

could also be water in the fuel, empty the fuel filters into a glass container and let it stand for a minute, if it's water you will see it at the bottom.

Re: Help possible vapor lock????
 

That's exactly what I was thinking... happened to me with a merc260 and every time the bow started to rise the water in the filter would cut off the fuel and it would die.

The thing is... if you empty the water/fuel separator or put in a new one... you need to pre-fill it with some fuel or it will take forever to get it started.

Re: Help possible vapor lock????
 

We've had boats in south Texas that have run fine for years. Many all of a sudden started having running problems similar to yours. All mechanics are saying it is the new gov't. required ethanol added to the fuel here. You may want to check to see if the ethanol has been added to your fuel. We're still trying to find a solution. If the marinas don't drain their regular fuel tanks prior to adding the ethanol based fuel, it causes all the water from moisture in their tanks to be mixed throughout their fuel and then their water drain systems are useless.

Re: Help possible vapor lock????
 

Yeah I emptied it but I was out on the water and just put it back on, it wouldn't start but I know that motor ran fine because the problem switched motors. I have a feeling it is Vapor Lock or bad gas because they did put Ethonal in the new gas, for the price we are all paying for gas you think that the last thing it would do would cause issues with the boat!!!!! I will put new water seperators on and fill them with gas, hopefully this will fix it.

Re: Help possible vapor lock????
 

If it was vapor lock, the motor should start and run fine once it had a chance to cool down. It hapened to me about 3 weeks ago and the next day the motor started and ran fine.

Re: Help possible vapor lock????
 

Question - Do you currently have the plastic covers/shrouds/guards around the fuel filter/water separator?

I've seen many boats where the owners or their techs change the fuel filters and never put the covers back on. They are there to keep the fuel in the filter from getting hot causing vapor lock. Many people think they are there to look pretty - but they do serve a purpose.

I've attached a .bmp - #'s 14 and 15 must be in place!!

Re: Help possible vapor lock????
 

Yes the plastic covers are still there, I took them off yesterday only to switch the filter to see if that was the problem. I am assuming that when they both wouldn't start and I let them sit for a little while that is probably why one of the motors started and ran fine. My concern is will this happen again, how do you own a boat that you go away on and have to worry about this happening once again???