Possible vapor lock

twright

New Member
Sep 8, 2015
4
Missouri
Boat Info
2000 230 signature open bow.
Engines
5.7 mercuries
New Sea Ray owner and so happy. I bought a 2000 230 open bow. Took it out this past weekend for the first time. Here is my problem. I ran it for over an hour. Then when we tied up for about 30 to 45 min's. Went to start it and cranks over and over but won't start. Got towed back in and had a mech come look at it the next morning. That morning it fired right up. He thought a good start was to replace fuel filter. He said it was clear and no contaminated. Took it out for the day and when it got hot it did it again. Would not start. Open the throttle body based on mech recommendations. Would not start. After about 1/2 hour with engine cover open it started. Mech thought it might be vapor lock. Any suggestions? Talking to other boaters thought thermostat issue. Boat temp holds at 170 after running for hours and after sitting for a few hours it only dropped to 130. New owner needs help? Thanks
 
Had similar problem w/ merc 4.3. Blamed it on a buddy that put gas station ethanol gas in it. When I finally got about 60 gal of good gas back in it I had no more problems.
 
Ethanol based gas will vapor lock at a lower temperature than non ethanol gas.
some suggestions- idle for a bit at the end of a long run, run the blower for a while after you shut down to cool off the temp in the engine compartment. All else fails, put a low pressure pump in line if you do not already have one.

i am not sure it is vapor lock as that is not really all that common. Could be an ignition issue that cuts out when hot. You should check for spark next time it happens to rule out other issues. As mentioned above, you could spray a little carb cleaner in the throat when it is happening and if it does not try to fire, it is not a fuel issue.
 
If you figure out it is vapor lock, that make a heat shield you can wrap your fuel lines with . Your not saying much about which fuel delivery system you have
 
After rereading your post, you say throttle body. So if it's TBI not MPI, you should be able to see your fuel spray with the flame arrestor off. Verify that
 
Tw,

I had the problem once years ago. I was running along at 3200 rpm and the air temp was near 95 degrees. I shut the engine down and had it took several attempts to start. From that point forward, I have always let the engine run at about 1000 rpm in neutral with the blower on before shutting her down after a long run. Also, try a search under CliffA in the engine section or better yet send him a PM. He had a similar issue with his previous boat powered by a 5.7. FYI my 5.7 has run about a needle's width over 170 degrees since new.
 
If it is indeed tbi, look to see if fuel is spraying out the injectors (already mentioned) as it turns over.if it is, unplug the plastic clips to both injectors (takes 2 seconds) to stop the fuel flow and try starting it. If it fires, you have the same problem I did, which is that it was dumping to much fuel on the initial crank stage. I'm not sure if you mean In your original post that you left the throttle open as your stating it. But as a habit, after I park, and shut the engine down (no post idle needed). I reopen the throttle body to allow unburned vapours to escape. This way it gets a clean dry start when I'm ready to leave, be it 2 minutes or several hours. At least with the injectors unplugged, if it restarts temporarily, you can narrow it down to a fuel issue and not electrical.
imagejpeg
 
Yes the fuel is spraying in nicely. I will try your suggestion. Thank you so much
 

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