2012 115 four stroke runs fine then dies

skijunk

Seaman
Joined
Jul 18, 2016
Messages
55
This is an ongoing problem and with my limited knowledge I have done what I could. My brother bought a 2012 Berkshire pontoon with a 2021 merc 115 four stroke. It will cold crank and idle fine. We can even lower it on the lift, tied to the dock and under load at 3500 rpm it runs fine. Today we let it run like that for about 10 minutes and it ran great. We are not getting any signal warnings. He has already taken it to a boat shop and the tech said he pump
Water from the tank, cleaned the spin on filter and checked other filters. Aside from that they say it runs fine but it doesn’t.
Fuel filters are clear
Hoses are not collapsed
I have blown through the tank pick up and it seems clear

So after I worked on it today his son takes off across the lake and about 8 miles out it dies but luckily in front of my parents house and I happened to be over there. I went out and it will not crank or hit a lick so we had to leave it tied to the dock.

What next ?
 

skijunk

Seaman
Joined
Jul 18, 2016
Messages
55
Troubleshoot the starting/electrical systems

Aside from dying randomly what other poor running symptoms does the motor have?
There are no other signs or warnings. It will run fine for a few mikes then start sputtering and die. Then it will not crank until it sits for several hours.
 
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