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Ask Dominick Your Own Question
Dominick, Marine Mechanic
Category: Boat
Satisfied Customers: 1009
Experience:  25 Years Experience as Mechanic, 20 Yrs Boat Yard Owner/Mechanic, Factory Certified
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Jason, I have the same issue as a question you answered 4

Customer Question

I have the same issue as a question you answered 4 years ago.2010 yamaha 4 stroke will not start after running awhile(getting hot).I believe it would run until I ran out of gas if I let it.There is no indication anything is wrong until I shut it off.I have been running it with the motor cover off and it starts everytime without issue.It's been going on for about 3 years now.I have replaced the stator with no luck.When it's cranking and will not start it also is dumping some fuel.I was givin some advise it may have something to do with the fuel cooler.I finally checked that out.Nothing seemed to be blocked but the hose off the out end was off the cooler AAha I thought I had found the problem.Put that back on tried it yesterday and same thing after it really warmed up it would not start 10 minutes after shutting down.Took off the cover,waited 15-20 minutes started right up and continued to start as long as I left the cover off.The joint to exhaust guide was the hose that came off .Could something on the back end of the exhaust guide have caused that to pop off that is still preventing water circulation ?
Submitted: 11 months ago.
Category: Boat
Expert:  Jason replied 11 months ago.
Hello my name is ***** ***** am I speaking with/ What is the model number on this engine?
Customer: replied 11 months ago.
Hello,My name is ***** *****'t have the exact model number at present .It's a yamaha F40
Expert:  Jason replied 11 months ago.
Hi Joe, If the engine is not starting it is missing either spark or fuel. It's is common for ignition components to work when cold, fail when hot, and work when cold again. Fuel injection engines do not usually get vapor lock, but it is not unheard of them to get vapor lock. Where you need to start is by duplicating the problem, and then when it will not start check for spark output with a timing light, and then check for fuel pressure with a fuel pressure gauge. Is that something you can do?
Customer: replied 11 months ago.
Unfortunately,there is no guarantee when it will fix itself.By the time I get a fuel pressure gauge hooked up or even a timing light it may fix itself (so to speak) and I would be getting an inacurate reading.I believe that troubleshooting would only positively work if would break and stay broken
Expert:  Jason replied 11 months ago.
You wrote "will not start after running awhile(getting hot)." How long exactly does it take before it will restart? Within a minute or two? 1/2 and hour? Hours? Overnight?
Customer: replied 11 months ago.
It seems it depends on ambient temperature ,yesterday was not to hot so it took about 10 minutes ,couple years ago it was a hot day it took around an hour.It seems obvious to me that some component is malfunctioning due to heat build up.I did a spark plug arc test,it was hard to see in bright sunlight .Thought I was not getting spark so I replaced the stator.There weas a recall on a fuel pump update which was done 8/13.What would cause a problem with fuel or spark related to heat?
Expert:  Jason replied 11 months ago.
Does this happen every single time you use the engine, or is it intermittent?
Customer: replied 11 months ago.
Like I said before I have been running without the cover to avoid the starting issue,so I would say it is pretty much guaranteed if I run it until the target temperature is reached it will not start every time.
Expert:  Jason replied 11 months ago.
If you are going to try and DIY this you will need to run the engine with the cover on, duplicate the problem, and when it will not start as quickly as you can pull the cover off and at least check for spark. If it has spark then we know it's a fuel pressure, flooding, or vapor lock issue. If there is no spark then the engine needs further diagnoses to figure out why. Is that something you can or want to do?
Customer: replied 11 months ago.
You never answered my question on what would cause fuel or spark problem related to heat sensitivity besides stator which had been replaced or fuel pump issue which had been addressed.I think I will take it from here.Thanks but I I was looking for a silver bullet(exact fix to an exact problem you may have encountered before).Your reply will end this conversation leaving me not really knowing anymore than when it started.
Expert:  Jason replied 11 months ago.
Sorry, but there are no tricks or shortcuts here. If you hired me in person to work on your engine you would be paying me to go out and do the tests that need to be done. No magic 8 balls, no tricks, no shortcuts, It all comes down to duplicating the problem troubleshooting and troubleshooting the issue. If you had different expectations here then you would need to take this into the dealer.

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