Force 5 hp outboard

kieron riley · 27 Mar 2024

i have a force 5 hp outboard with a probable carb fault it starts and runs for a very short time then fuel comes out of the air in side of the carb and it cuts out. The float and the and the small pin that cuts off the fuel seem to be in good condition and i can se no reason why they shouldn't work so ,any other ideas(new carb not an option as they are no longer made) Thanks for looking.Kieron

VicS · 27 Mar 2024

kieron riley said:
i have a force 5 hp outboard with a probable carb fault it starts and runs for a very short time then fuel comes out of the air in side of the carb and it cuts out. The float and the and the small pin that cuts off the fuel seem to be in good condition and i can se no reason why they shouldn't work so ,any other ideas(new carb not an option as they are no longer made) Thanks for looking.Kieron

But if it is flooding either the float or the valve is defective. It may be a bit of dirt on the seat or a worn needle.
Unlikely to be a defective float but not impossible.
New needle may be needed . Off hand I don't know if the seat is replaceable.

kieron riley · 27 Mar 2024

thank very much, i did think that i had inspected them well enough ,but your thoughts are exactly the same as mine,so i will delve in once more

thinwater · 27 Mar 2024

^^ Yup, had the same problem. Worn needle in my case. Previously, different motor, I had a float that got heavy over time.

greeny · 27 Mar 2024

While you're in there check the float hasn't got a hole in it and filling up then sinking.
Sorry Vic, just seen you mentioned the float.

mabbs · 1 Apr 2024

As well as the float valve pin, and throughly cleaning carb, the fuel pump diaphragms can go weak and should be replaced. Had similar problem on a small 4 stroke and that was the cause.

kieron riley · 17 Apr 2024

I still haven’t managed to fix this problem , however during my search of the internet I found a sheet containing a breakdown picture of the carburettor that had a footnote under the float valve , saying . Warning do not remove the float valve holder , well I have , and I’m sure it will have been removed before ? Does anyone have any idea why this might be. There was I what looked like a very small copper washer at the seat of the small brass valve holder, I’m wondering could it be that the holder didn’t reseat properly after its initial fitting .

kieron riley · 17 Apr 2024

sorry it actually says "DO NOT REMOVE INLET SEAT"

VicS · 17 Apr 2024

If you are saying that the needle valve holder screws down onto a copper washer. Anneal the washer if reusing. Heat to cherry red and allow to cool. Quenching is not necessary.

I assume by "inlet seat" it means the actual valve seat ie where the pointy end of the needle sits

kieron riley · 17 Apr 2024

Hi Vic and thanks again , I think that’s correct as the warning is written below the description of item 17 in the spares list and item 17 is the needle valve.

kieron riley · 18 Apr 2024

sorry me again i have the carb off again and the copper washer at the base of the valve seat has definitely been overtightened at some time there is an indent in it all round the mid area of the washer face and on the outer face a very small ridge that doesn't go all the way around the outer edge of the washer. i have annealed it twice and it is exactly the same after that . This is probably why the warning is there as it will never go back on exactly as it came off. now im sure that i can get one of these little washers somewhere ,but how many am going to have to buy to get the one i want. Thanks and sorry for my continued questions on what may appear to be a boring subject

VicS · 19 Apr 2024

kieron riley said:
sorry me again i have the carb off again and the copper washer at the base of the valve seat has definitely been overtightened at some time there is an indent in it all round the mid area of the washer face and on the outer face a very small ridge that doesn't go all the way around the outer edge of the washer. i have annealed it twice and it is exactly the same after that . This is probably why the warning is there as it will never go back on exactly as it came off. now im sure that i can get one of these little washers somewhere ,but how many am going to have to buy to get the one i want. Thanks and sorry for my continued questions on what may appear to be a boring subject

I sounds as though you will need to replace this washer.
Maybe a Dowty bonded seal would be an alternative to a copper washer but it would have to be compatible with petrol containing ethanol. I think that means a seal made of hydrogenated nitrile rubber (HBNR).

At present the assumption is that the copper washer is the cause of the flooding and that the needle valve is OK but until the copper washer is sorted out we don't know for sure that the needle valve is OK

Force 5 hp outboard

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