emergency clean fuel supply

[pcatterall]

We have mucked out the port tank and will shortly do the same to the starboard ( working ) tank. Fuel supply failure remains a concern though in that we have no fall back except changing filters/bleeding etc in a difficult engine compartment and no doubt in horrible conditions.
We are trying to consider the biggest causes of breakdowns, how to avoid them and how to get round them if our avoidence measures fail!!
I have considered a small emergency gravity tank.
The only way I can see to fit it is direct to the second filter bypassing the water bowl, the coarse filter and the pump. There is no spare inlet on this filter so I thought we could just remove the existing inlet from the pump and fit the emergency one in its place ( we would have to blank the existing pipe to avoid fuel being pumped)
I suppose that if I could find a Tee which could be switched to supply from normal to emergency then this would simplify the switch over.
The tank would be up to 5 gallons and kept full of clean fresh diesel.
Advice appreciated.

 

[rob2]

Some old school installations use a day tank mounted higher than the engine. Fuel is pumped through a filter from the main tank(s) to the day tank and then gravity fed to the engine. The advantages are that a partially blocked filter will only slow the refilling of the tank and the day's fuel supply is a known filtered supply, even if it's infected with bug. Also, fresh fuel from the garage can be added direct to the day tank if needs be. The engiune will continue to run even if the lift pump should fail.

Your proposal might well suit the way you use your boat, but also consider where the return is fed to. Many engines pump twice the required fuel and so your 5 gals will only yield 2.5 gals - the rest being returned to the failed main tank. When using a day tank, the return is always fed to the day tank...

Rob.

 

[fisherman]

The engiune will continue to run even if the lift pump should fail.

Will it? Mine needs pressure equal to a 16ft head. I would carry an outboard tank for the emergency spare: easily refilled, and the added bonus of a squeezy bulb for priming.

 

[Dockhead]

Sounds like a great idea. I have often thought about it myself.

For the return, I always thought that the return line should also be diverted to the emergency tank.

If the emergency tank can be rigged as a day tank with gravity feed, so much the better -- also an emergency work-around to the lift pump.

For the dog's b*lll*cks of fuel systems, which solves this and many other fuel system challenges, read and drool:

http://www.sv-jedi.org/sv_jedi/2006/11/a_new_fuel_syst.html

Wow! We can dream, can't we?

 

[A1Sailor]

Your proposal might well suit the way you use your boat, but also consider where the return is fed to. Many engines pump twice the required fuel and so your 5 gals will only yield 2.5 gals - the rest being returned to the failed main tank. When using a day tank, the return is always fed to the day tank...

Rob.

Sage advice! The tank on the Moody336 I used to own was full of bug, and the 35HP Betamarine wouldn't run. As an emergency "get me home" from Rhu to Largs (20miles?) I used a 20litre can of diesel with a rubber hose. Perfect!
At least it was until the can virtually emptied by the time we reached Kip after 10-15miles
"Get me home" involved a bit of sailing! You live and learn...

 

[prv]

Instead of an emergency tank, how about a modified second cap for your jerrycan of spare fuel? This cap would have a hose fitted to it, and the other end can connect to a suitable point on the engine (either with a pre-prepared fitting or, more flexible but more fiddly, just a jubilee clip ready on the hose). The jerrycan can then sit in the cockpit and gravity-feed to the engine. Takes up minimal extra space (assuming you already carry a can of fuel) and could also be used to help bleed filters, diagnose blockages, etc.

Pete

 

[pcatterall]

Thanks guys.
I had not realised that so much fuel is returned so 5 gallons would be the size I would go for, and then in the knowledge that I would have only a couple of hours fuel.
Thanks PRV, I used tank in a fairly loose manner, certainly gravity feed was a key element of the plan. We carry a total of 100 gallons with both tanks full so extra spare fuel has not been an issue but spare 'known to be clean' fuel could be a comfort!
Thanks again

 

[rob2]

Just revisiting the idea. I've also heard of a day tank with a float switch system to control the transfer pump, which means that you don't have to transfer the return to the day tank and the system offers the benefit that twice the amount of fuel is filtered during the transfer. Should the filter on the transfer line block, you still have a tankfull of fuel to keep you going whilst you change it and no need to bleed it afterwards.

Rob.