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Wont start in HOT sun after sitting an hour

PaulAlford

New member
This has happened several times now...
My BF115 HP ran perfectly to get to your fishing spot 20-30 min, sit for an hour or so in the HOT sun and then doesnt want to start? Mine has been doing that. I am wondering if something to do with vapor lock. Two trips ago it did this (sitting in hot sun for an hour after running perfectly) I got another boat to start pulling me in and 2 min into moving I tried it again and it cranked right up. This time (today) I ran it for 20-30 min up and down the river then anchored down for an hour or so and then wouldnt start again. Would turn over and turn over and turn over. I vented the gas tank, pumped the gas bulb, still nothing, I started paddling out 15-20 min trying the motor again here and there and it finally started again and ran perfectly again. I think it has to do with the HOT fuel or something related.
I really dont know if it is electrical or fuel related.

Anyone have some ideas?

 
Well I still learning theses things but my thoughts are electrical. It gets hot then sits and has some temp rise which in turn causes something kick out. I know going out on water to test is concerning but carry a spare spark plug for spark test ans maybe a way to squirt fresh gas into one of the intakes and see if it hits.
 
What year is your outboard? Fuel injected or carburetors?

If you can remove the cover without too much trouble see if it makes a difference. If so, that might be an indication that your thoughts about vapor lock might have merit.
 
Definitely vapour lock, check you water flow to and from the fuel cooler on the side of the vapour separator, see that they are clear and that water is flowing freely.
 
Thanks for the replies folks. I am scared to mess with the water lines since one goes way under the VS (I think that is what that device is) and if I pull the water line off, I will never get it back on. I am a NOVICE and trying to fix this myself. Is there an easy/safe way to check the water lines without tearing things off the motor? It flushes fine when I drop it in a barrel at the house. I do notice the tell tell does flow really well sometimes though..and I can pull the T fitting and clear it out once or twice and it starts flowing better out the tell tell.

When I separate the water line from the T fitting the water flows fine from the line coming from the back to the T (A in pic) ...the other side is nothing (B in pic) (zero flow) but I am guessing that is normal since I disconnected the T. I think the water comes from the back to the front and tube runs back behind the VS (vapor separator) and like I said, I am scared to fiddle with that line (I will never get it back on). Attaching pic showing A side water flow from the back to the T fitting and B runs back behind VS.
5a.jpg
 
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I was also thinking I would cover the fuel lines under the cover with reflective/heat shield tape to reduce the radiant heat to those lines and be sure the hull gas tank compartment has the vent tube clear too. I will run it out next to the house today later in the hot sun and see if I can reproduce it not starting when it sits for a while after running perfectly.
 
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