New fuel tank issue

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Ardenfour

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I have a Volvo MD1, which is gravity-fed from a steel Stuart tank slung up under the stern deck. This is an original 1966 job, and has seen better days, rusty inside, leaky fuel tap etc.
Last boat jumble I acquired a Vetus plastic tank which, though taller, I can squeeze under the side deck. This brings it closer to the engine and frees space in the aft locker. So far so good. But the plastic tank has the fuel outlet from the top of the tank with a pickup pipe inside - old tank had the outlet underneath. Is there likely to be enough suction to syphon the fuel over the top of the tank and then down to the engine? The height drop is around 400mm. Or do I need some kind of pump? Opinions, please, before I start ripping stuff out.
Thanks
 
I'm about to start exploring the same route. One suggestion I had was to fit an outlet low in the sidewall of the tank - the idea was that someone surely must produce a flange type fitting that's leakproof and has a suitable thread.

In my case squeezing a bulb would be a bit of a pain, due to the fact it would all be under the cockpit floor engine hatch.
 
Can't comment on your Volvo and whether the pump is capable of pulling the fuel - but I did exactly the same as you when I replaced an ST with a Yanmar 1GM and installed the Vetus tank. No problem at all with the pick up.
 
The only problem I can see MIGHT arise when first installed and if you ever run the tank dry, and that is whether there's enough suction when bleeding to overcome the air in the pipe. Don't see why there shouldn't be, but logic applied to boat mechanicals doesn't always seem to work.
 
I don't understand some of the answers here (or perhaps the question), surely a tank with a top tube going down to 1cm. above the bottom has a head only 1cm. higher than a tube coming straight out of the bottom with the advantage that it is much less likely to lift water or crud ? It does reduce the usable capacity slightly but the actual head is determined by the level of fuel in the tank no matter where the pipe leaves from?
Or am I missing something? Again.
 
Last edited:
Quandary said:
I don't understand some of the answers here (or perhaps the question), surely a tank with a top tube going down to 1cm. above the bottom has a head only 1cm. higher than a tube coming straight out of the bottom with the advantage that it is much less likely to lift water or crud ? It does reduce the usable capacity slightly but the actual head is determined by the level of fuel in the tank no matter where the pipe leaves from?
Or am I missing something? Again.
Click to expand...

Everything you've said is correct, but only applies once the pipe is filled and the siphon established.

Personally I would just fit a squeeze-bulb, which might be useful for bleeding filters etc too. They are ok to use with diesel, at least mine said so on the packet.

Pete
 
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