New Mercury 600 starting problems when hot
 

I have a brand new 600 in my new boat and it does not want to re-start after it sits for about an hour after a run. Cold start is fine. Mercury is saying it's from the heat and the fuel is boiling in the rails. Outside temp was 105. I tried opening the hatch to cool with no luck. I tried turning the key on and off to cycle fuel with no luck. It still takes about 8 tries to get it to start. Anyone else have this problem?

I had the exact same problem with one of the 525's in my boat. It turned out to be that I had R&R'd that engine and when it was put back in the boat, the main fuel line was too close to the bottom of the engine. I lowered it and it solved the problem. Having said that, your outside temperatures are much higher than mine so it sounds like you could be experiencing a heat soak flood condition and the fuel maybe boiling off. Make sure your fuel cooler is not clogged also.

Heat soak is what they are saying but there are many other guys running the 600 in hotter temps with no issues. You would think a brand new motor would not have this issue. Ugh!!!

It's not always the motor, but the engine compartment that it sits in.

What could be wrong with the engine compartment? Not enough air? I open the hatch after each run and let it cool and still no luck.

Are you running E10 fuel ????

Yes. That's all they have in my area. I did hear that the ethanol separates from the fuel in temps above 100. I wonder if they make something that will stabilize the fuel if that's the problem. My last boat and all the other boats that use the same fuel are not having this issue. I wonder why the 600 is so different. Thanks for the help.

sounds like vapor lock to me

could be check valve in the electric fuel pump

other possibilities could be coolant temp sensor or IAC as well so have engine scanned and fuel pressure checks and fuel vacuum tests

Fuel vacuum test thats are higher than spec can cause huge vapor lock issues among other problems.

E 10 separates when water in the fuel is present. take some fuel samples in a clear jar to look at. water mixed with E10 sinks to the bottom and fuel sits on top.

your engine is new I would have a Merc certified shop and the Merc rep look at it and warranty the issue(s) instead of everyone throwing darts up here about it including me. We all are blind trying to fix a new motor here that's what the warranty is all about as well. Complain about the huge inconvenience you are having. Call Merc is the best advice I can give you.

With the warranty you can take it to any Merc dealer in the world as many times that is needed to get it fixed to your liking.



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forgot could be anti siphon valve on top of the gas tank that the fuel line is connected to that is sticking from heat soak. Sometimes those anti valve valves can be just as much a problem when brand new compared to 20 years old.


Been there with new boats as well that experience problems the anti siphon valve.