Mariner 100hp

[Lavy]

Hi all, just wondering if anyone can help. A mate of mine has a 100hp 4 stroke mariner that was running fine until last week.
Now it will only go for about 3 miles and then cuts out. If you leave it for a couple of minutes it will run for another 3 miles and so on.
He has had it checked out by a local mechanic who cant find anything wrong with it. They have cleaned the entire fuel system , it is not overheating or over reving and there are no alarms. Has anyone ever experienced anything similar?
Got to try and sort him out cos he is getting despondent and talking about selling the lot and giving up fishing and i cant let him do that.

Rich.

[olly]

3 mile seems a long way for it to be fuel.id go for water sensers, tell tale flow, water jacket.
you say its not over heating but it might be at the senser limmit and killing the engine so it wont over heat and blow the block
im no expert but iv just had loads of faults with my outboard but its all sorted now.it took me 3 weeks but i no all about the engine now

has ya m8 tested it at slow speed say 5kts to see how far it gets before shut down
is it ok on tick over?
im not sure but i was told the alarm will only go off when the fault hits the highest limit

id be looking at the water cooling side of things first

good luck
olly