Generator installation - fuel lines

[Pumphrey]

I'm installing a generator and need advice on fuel lines.

I am nervous of drilling the main fuel tank so am exploring using a three way valve in the engine supply line on the basis that I do not anticipate ever using the generator at the same time as the main engine.

If this idea is workable could I use a simple tee piece for the return line. The lines after the tee piece are at least two metres before they reach the engines.

All the generator installation manuals suggest this set up is a no no but I cannot work out why.

Thanks for any help

 

[boatmike]

I'm installing a generator and need advice on fuel lines.

I am nervous of drilling the main fuel tank so am exploring using a three way valve in the engine supply line on the basis that I do not anticipate ever using the generator at the same time as the main engine.

If this idea is workable could I use a simple tee piece for the return line. The lines after the tee piece are at least two metres before they reach the engines.

All the generator installation manuals suggest this set up is a no no but I cannot work out why.

Thanks for any help

The main problem is that if you forget to switch over the valve before starting your main engine you could suck air down the line to the genny rather than fuel. This, in the wrong circumstances, could stop your main engine just when you need it and you won't re-start it without bleeding the whole system. Not a good idea to introduce anything into your system that could go wrong if you forget something..... The return line should not be a problem as you are dealing with positive pressure rather than negative (blowing rather than sucking!)

 

[Chris_Robb]

The main problem is that if you forget to switch over the valve before starting your main engine you could suck air down the line to the genny rather than fuel. This, in the wrong circumstances, could stop your main engine just when you need it and you won't re-start it without bleeding the whole system. Not a good idea to introduce anything into your system that could go wrong if you forget something..... The return line should not be a problem as you are dealing with positive pressure rather than negative (blowing rather than sucking!)

+1 Absolutely essential not to introduce a mistake factor here. I remember once I had turned off the main deisel tank tap to the main engine, I had forgotten I had done this. The engine started fine on idle, but as soon as we were out in the channel - any load gave no increase in revs. I soon realized my mistake. It was lucky there was no tide or anything to hit.

Drill a new hole for an exclusive supply. It does not need to be at the bottom of the tank. If you are that low on fuel, then the generator running out of fuel might be a good thing! Do put a good filter in line. Most gensets seem to rely on a small inline filter with no water separator.

 

[chrisb]

fuel lines

I have this arrangement.The take off is after the fuel filter-a tee piece.The genset is in a cockpit locker and higher than the engine.We have an inline booster pump to the genset.My set up is volvo 55hp engine with Paguro 3kw genset.I can if necesary run both together although seldom do so as we choose to travel under sail

 

[chrisb]

fuel return

as far as I recall the return is via another t-piece.can't look at it now for you as boat is in Trinidad

 

[Marsupial]

Investigate your fuel tank, it may have two or three blanks in the TOP for extra fuel take offs, in which case you just need a dip tube. In any event drilling holes at or near the bottom of the tank is not a good idea, a dip tube in the top is the way to go, the assembly will also have a pipe on it for the return fuel so you don't introduce any possibility of strange fuel supply related faults caused by messing with the main engine fuel supply.

As a general rule with engines its one pipe one job, combining fuel pipes can have unexpected results, like all of a sudden all you get is air and no fuel or every time you switch off the system air locks (so where does the air come from) - the other engine usually by some "backdoor" vent in a lift pump so then you go round fitting non return valves everywhere but things don't improve. Yes I know some times you can "get away with it" but its not good design. If I had a boat like it even if it worked it would be a priority job to change it.

Its such a well-known vulnerability that the rule is one pipe one job.

Its worth doing it properly.

 

[Jamesuk]

I'm installing a generator and need advice on fuel lines.

I am nervous of drilling the main fuel tank so am exploring using a three way valve in the engine supply line on the basis that I do not anticipate ever using the generator at the same time as the main engine.

Thanks for any help

Dont be worried about drilling into the tank, Open the inspection hatch get a hoover and a friend holding some sort of net below. Get drilling! I just put two fuel pipes in the main tank. Its not the end of the world if the steel drops into the fuel tank. You can always recover it later or leave it like Osm..... )

Better follow the instructions it will just give you grief later on. Or alternatively have a separate tank for the genset and a fuel transfer pump. I also think you might present air in the system although without looking....