I'd be a bit interested to know what work has been done on this engine previously, first thing is to get the basic timing and carb settings checked, if they are OK then has the engine had any big repairs which would require the cam timing to be disturbed as the symptons sound like the valve timing is out, the fact that it won't rev under load is a pointer.
If the pump diaphragm was split you should see fuel going up the transparent plastic tube from the pump to the carb and see it being dumped into the venturi.
Thanks Spannerman
the plastic tube you are talking about, is it the one that goes to the fire guard thing that sits on the top of the carb?
Also if the timming was out, which incidently has NOT ben checked, would this be the reason why the boat uses loads and I mean loads of fuel and also why you can smell it strongly when it is going in open sea and also when idling on the pontoon?????
Thanks again
Following on from another post regarding Sea Start.... I haven't subscribed to their services so don't actually know the answer to this but wouln't this be a classic case for them to sort out if Daddycool were a member? Are Sea Startlike the AA (Automobile Association not Alcoholics Anonymous!!!) or RAC, whereby you can join even though you know you have a problem?
The boat will us loads of fuel if it isnt getting onto the plane (which at 7 knots it wont be). It is just effectively pushing a wall of water along in front of it. It takes a lot of power to get a boat up over the hump and start planing properly.
It sounds as though you need an engineer to have a good look around her for you and then take her out for a quick spin. Smaller boats like these can be very dependant on weight distribution to get up onto the plane, 2 adults and 3 kids and all the kit that goes along with them may need distributing a little better. Stick a few up front and see if it helps any.
Hi Daddycool,
it sounds like a pretty serious problem if the boat is supposed to do 35 knots and only does 7 or 8. You can discount a dirty bottom or prop problems, the bottom would only account for a few knots and if the props were at fault you would have serious vibration.
Did you get a sea trial before you bought it? And did you buy direct from the owner or through a broker? If a broker was involved he should try to get to the bottom of the problem for you.
Hey guys
thanks for all your inputs, I am really pleased with the response I have had, I am new to boating and to forums and I have found this a very helpful and pleasant experience, I never realised how friendly a forum could be.
Seeing as the problem I have is beyond my capabilities as an engineer ( but not the marine type) I have heeded your advise and employed the services of a local recommended marine engineer to take a look, take the boat out, diagnose the fault and then drop the bomshell of how much it is going to cost me to put her right!!!! ( unless its something I can do myself of course)
I will let you know the result.
Once again a big thank you to you all