I have here some nice new boat 27 gallons poly fuel tanks, suited gas or diesel. They have inlet, 2 outlets and sending unit.
It would be nice to be able to buy extra fuel where it's cheaper (eg Montana is $ 4.50, Seattle $ 5.09)

If I connect it to main fuel line will pump draw from both ? Or should I add a switch valve ?

 

buy a gravity feed line and all you need to do is mount it and fill it

 

I have considered the simplicity and cost advantage of gravity flow, but I am pretty sure that to make it DOT legal it must draw from the top via a pump and not be gravity flow, for safety reasons in event of a wreck, so it does not continue to flow if a line is severed.

 

Yeah be careful and make sure you read your states DOT laws some states will not let you use poly tanks.

 

it's your truck, don't worry about DOT or any body else unless you are a commercial Carrier

 

I suggest if you run gravity flow that you carry at least a $2,000,000 umbrella insurance policy "just in case" the diesel pouring from a gravity flow tank contributes to a fire in a wreck and things go from bad to worse.

I realize disel is slower burning than gas, but it is still a flammable petroleum product...

Just my 2 cents worse.

 

OK, that stops everything, I am a commercial carrier.

It was a good thought though. Thanks everybody.

 

Don't let it stop everything.........top draw from that one you have (as long as the tank has a certification number), run a hose, mount an inline filter / two way solenoid valve / pump all under the box to pump into a "T" in your vent line to fill the OE tank, and you're good. Kind of like this:

 

The secret to gravity feed in most states is "where" does the fuel go when it leaves the tank. OTR trucks use gravity feed all the time between their saddle tanks. You cannot feed directly to the fuel pump. If you feed into your main tank, in most states you are fine. Kinda beats me why a poly tank is a no no when it is in the bed - - what is the tank under the truck????

Take a peak at this write up I put together on installing a gravity fed tank. No electric wires to run, no pumps, no electric switchover valves to stick - - basically nothing to go wrong. And sure a whole bunch cheaper than other installs. Mine has worked flawlessly for many thousands of miles.

https://www.dieseltruckresource.com/...n&onlynewfaq=1

Bob

 

What about just going to a 75 gallon under bed tank (Transferflow) or a DOT approved in bed tank with a pump?

 

Who's paying the $700 difference in price??? OUCH