Engine stalling under power

[lukewhiting]

I saw a thread not long ago about the same problem but cant find it now.

I've got a 115hp yamaha V4 that runs absolutely perfect! However sometimes (never when cold) powering up the engine stuggles at about 1/4 throttle and then will either die or cough and be fine again.

ive also worked out that to overcome the problem when the engine struggles flick the electric choke on and it will suddenly pick up revs and be fine.

The engine runs perfect at WOT & tick over and once cruising its fine. its just the powering up stage getting the boat onto the plane & again it doesnt do it all the time.

Seems to me like fuel starvation? or dirty feul? anyone with any other ideas?

[Roflhat]

9/10 times it's a fuel problem, make sure everything is clean first, carbs as well

[1eyedjim]

My zapcat was doing this the weekend and the pilot screws were seized in. Cleaned and freed them and rest them and all is good now

[lukewhiting]

I'll have a fiddle and see what I can do

[Nightfisher]

Dirty choke lever (sticking). Choke out of adjustment at running temp.

[lukewhiting]

Weirdly was absolutely fine the other evening so we will see how it goes!

As for dirty fuel had a look in the tank
& noticed one of the previous owners cock ups! There's a oil bottle cap & seal floating around in there!!