Prop choice

[Ianfs]

I think these are the things to check out first, I learned a lot form Ed when he helped me strip my carb and you know, once you've done it, it is dead easy. If you check your engine number on the Keypart website and this link you may find this kit will work for you at not a lot of pennies!

http://www.keypart.com/stock/18-7095

For me, once you know the carb is ok, if the engine is then ok you've cracked it, but if not at least you have eliminated it from your list.

[shibbs]

Carb kit ordered.. Will get on with that next week when it arrives.
Went down today and fitted the new coil and gave it another run, no change, at least that's the coil out of the equation.

[Doc Oakley]

This may be completely off the wall, but you never know: I had a similar problem with a Mariner outboard a few years back - would not idle without some throttle and was also getting thirsty. Did all of the spark/ignition checks and ultimately it turned out to be the fuel pump diaphragm - one of the cylinders was simply not getting enough fuel...now, the cylinder layout on that old engine is very different to what you have, but might just be worth a look at the fuel pump!

Simon.

[Ianfs]

That's a very good call Doc, fuel pumps on inboards can be expensive and cannot be repaired so you have to replace the unit. The way of telling they are faulty is by checking the clear pipe running from the pump to the carb, if its got fuel in it, it's faulty! I think Shibbs pipe is clear!

It's certainly a point to think about if all the other options fail!

[mlines]

There is a lot of discussion on the American forums about Ethanol supplemented fuels limiting the life of carbs, fuel pumps etc. They reckon it reduces life to only a few years. Diaphrams etc. fail.

[shibbs]

Thanks to all for all the suggestions.
I had been considering the fuel and pump. The fuel has been in for about 2 months but does have additive in it, but i hadn't considered the effects long term of the Ethonol. As for the pump, i will service the carb and then go from there. I even removed the fuel tap today and checked it just to eliminate it.
Martin, i think i read last night that you stripped your carb on your last boat, was it easy enough?
Oh, and i checked the choke today when cold and warm - closed when cold then opened up when warm so assuming that is working correctly.
Hopefully i'm zeroing in on the problem,, then i can ask about props again..

[_Ed_]

2mth old fuel will be fine. Ethanol in uk fuel is very small >10% not known that to cause a problem for anyone I know, or any of the engines I work on.

[mlines]

Carb rebuild was straight forward, some of the screws were tight so be careful.

check your carb rebuild kit comes with all the parts you need. My kit did not have the carb to manifold gasket which I guess is because is not part of the carb but any work on the carb requires it to be changed.

[shibbs]

Hooray!!!
The carb rebuild seems to have done the trick. Finally got out today for a run after refitting it. It now idles correctly at 700 rpm and ran nicely up to just over 4000 rpm. It's amazing how much difference a slight blockage that i couldn't even see can make.
I also took the exhaust elbows off today for a look as i had one slightly hotter than the other and confirmed that my elbows and manifolds are in good condition - another worry gone
Found the cause of that, i was possibly expecting some sort of blockage somewhere but found slight wear to the thermostat housing where the balls seal the flow to the elbows - a new one required at some point but not major.
As a finishing note on this, i'd just like to say a huge thank you to all of you knowledgeable people who have taken the time to help me figure this one out, would have been a long expensive route otherwise.
Whenever we all get together a cold one on me!

[Ianfs]

Good news Stu, glad I could help.

This might sound a bit picky but did you change the gaskets when you had a look at the risers?