DF115 2014 LP Fuel pump issue?

[oebb]

Hi!
Got a quite new DF115 with less than 100 hours. When running it at sea for the first time this year after winter, it ran smoothly for like 10 mins - I could rev upp to 4k without problems. Then suddenly the engine started stallin. I suspected water in fuel and had to go to harbour on 2k rev. Switched water separator filter and engine fuelfilter. Still same behaviour. I then had my wife give the primer bulb continuous pumps and then I can rev up to 4k without the engine stalling.
OK, I thought there's some issue with the LP fuel pump. The pump seem to be running fine - if I remove the pressure side and start the engine - the pump squirts gas. I also removed and dissasembled the pump. It looks brand new inside. Diaphragm is fine and the backvents are working.
I also tried running on fresh gas from a separate tank - no change. So before I spend X$ on a new pump - any ideas or comments? Could air in the fuel line play tricks?

Thanks.
/Mikael

 

[alldodge]

Not a Suz gut but will toss my thoughts for some maybe useless info

I see the motor using a VST and with that the tank and float may be the issue. have you tried removing the top to see if its clean inside? Could be the needle seat is hanging in the closed position

 

[99yam40]

4K is low for top RPMS
monitor fuel pressures into and out of the VST to see if both have a problem

yes sucking air can cause fuel starvation if it is bad enough

 

[oebb]

Ok, thanks - will investigate VST. About the 4k rev - it's my cruising rev - it actually revs to like 5,5 with full throttle (when not stalling).
Cheers
/Mikael