Suzuki 40 fires up but wont provide the grunt

[Red Fox]

suzuki 40 starts ok but wont pull away strongly or go over 20 mph. Serviced at Christmas and only just run today. Any ideas please.
Max revs 4500 and the last 1000 are missing!! Should max out at 5800...where are they?

[Nos4r2]

How old is the fuel? Stale petrol will do that.

[Biggles]

Could be allsorts of fuel related problems. We really need some more info. Have you really not used the boat since xmas.

[Biggles]

and 4500 revs only gives 20 mph. What did it give before the service.

[Red Fox]

will try new fuel today. should do 32mph at 5800revs. yes not used since christmas! sorry!! thanks for your thoughts on this.

[codprawn]

Could be blocked vents on the fuel tank - remove the filler cap and see if you can get the missing revs back. Also a kinked fuel line can do the same - great way of saving fuel though!!!

[Red Fox]

Yipee, 6000rpm and 35mph are back! All sorted guys, it must have been the winteriser and stale fuel in the pipes but it took two hours to burn it all off. Much relieved as rib raid on Sunday would not be such fun without the power. We go 10 miles out into Irish sea and intercept the big ribs coming over to Portpatrick. Their wake makes a 10 mile rollercoaster back into port for our small rib but it is one hell of a blast. Cheers all