tapping the deuce's fuel tank for a generator

[OPCOM]

making use of the deuce fuel tank to also run a generator would seem simple, but I could use some confirmation.

deuce fuel tank:
1. has a diesel fuel outlet
2. has a vent tube
3. has a fuel return tube

generator set:
1. has lift pump that can suck the fuel from the M35's tank outlet (whether or not the M35 centrifugal pump is running does not matter)
2. has a return line that has to go back to the fuel tank.

Do I just put a tee on the deuce's fuel tank outlet and return, and plumb the generator to those places?

Is regular fuel line (hose) OK for this? Seems it should be OK.

I would like to use a metal cased fuel filter (for durability) like used for gasoline on a car. Is this OK?

 

[WillWagner]

RE: tapping the deuce

Go thru the bottom, into the drain. Make a compression fitting, extend the pipe4 or5 inches up into the tank..so you don't suck debris and, most importantly, use all of the fuel in the tank and strand yourself. Look at the Mfg . intsallation instructions. Sometimes the returns need to be below the fuel level. If not, do the "T" into the engine return.

 

[Armada]

RE: tapping the deuce

I'd like to do the same thing one of these days. The fuel feed to your genset will be no pressure so rubber hose will work as long as it is rated for fuel. Use a heavy walled, reinforced fuel hose to prevent collapsing at any bends in the hose routing. Definately use an inline filter.
I've thought about putting a fuel pick-up in the tank and mounting an electric pump inline with a valve that I could use for filling jerry cans for refueling gensets, other vehicles, etc.

 

[Recovry4x4]

RE: tapping the deuce

Look into the multifuel arctic heaters. There are provisions for drawing/pumping fuel from the duece tank but I forget how. It can be done without disturbing the drain.

 

[cranetruck]

Like Kenny says, the winterization kits use fuel from main tank(s). This is from the 209-20, but no instructions. Note how the return is modified.

 

[OPCOM]

The electric fuel pump for fuel transfer seems like a good idea.. seeing I am lazy it would beat holding the can and pouring.. I have a holley electric fuel pump made for a hot rod. I suppose it would not care if the fuel were diesel. Going throught the drain plug would keep the generator's fuel line primed and free of air. Since I use the truck alot, I don't have to drain the fuel tank. The genset in any case has a manual priming lever on the pump and it works well. I like the winterization kit setup also. This removes some issues since it seems to re-use the return line fitting by adding the appropriate fittings. I see my answer to the question in another forum is answered by the picture here. the plug in the top of the tank is where they put the pickup.

The generator does not need the return line to be in liquid. It just dumps it into the top of the tank.

On this subject, you can turn those fittings round and round.. obviously it has to point the right direction. How do you know when it is tight enough and you don't want to go another turn?

 

[cranetruck]

....
On this subject, you can turn those fittings round and round.. obviously it has to point the right direction. How do you know when it is tight enough and you don't want to go another turn?

Just don't overtighten, add sealing tape (teflon) if it doesn't come out right the first time.

 

[rmgill]

Usually you can get the feel for it when you're tightening it up. There's also the plug on the top of the fuel pump on the deuce, 1/4" I think. You could tap from there for your generator set possibly.

 

[Westech]

If that is a flare fitting please don't add sealing tape. The threads is not what seals the line, its the flare. Doing that is just a bandage and it will leak someday. I see that done all the time at my shop by customers. Do it right now or do it twice later, that's what I say

 

[cranetruck]

Correct, but the "nipple" Patrick is referring to has pipe threads. The regular fuel lines have inverted flare fittings and do not get any sealer of any kind.

 

[Westech]

Super! I was about to say.... I like to use the "pipe dope" in a can. it really coats the nipple well (take it ez guys) and does not "oversize" the nipple. I have seen people use too much tape and really mess things up. With the "dope in a can" it just seals what it has to.

 

[jwaller]

Usually you can get the feel for it when you're tightening it up. There's also the plug on the top of the fuel pump on the deuce, 1/4" I think. You could tap from there for your generator set possibly.

this is what I was thinking. simply pull the plug and install fitting.

I have a pressure gauge in mine so I can check the operation of the lift pump.

 

[devilman96]

Patrick you can plumb the tank with one line and save a lot of trouble...

Install your fuel pump up by the gen set, tee the return line into the line before the pump... Use the 1/4 pipe outlet on top of the deuce's tank with a 90 degree fitting, drill the fitting and insert a piece of 1/4 hard line for a pick up tube, flux, solder and install...

This is what I have set up for my slave fitting in the back of my truck...

 

[OPCOM]

Thanks to the great advice so far, I think I figured this out so that I can:
1. tap the fuel tank at a level above the pump so as not to run the tank dry
2. provide a fuel return for the genset
3. avoid using the truck's pump outlet (concerns with it forcing fuel into the generator when the genset is off)
4. not drill holes in the truck fuel tank
5. do it cheaply

I will use the fuel return port on the tank by adding a tee and letting the truck and generator both return the fuel there as shown in the picture by Bjorn. I will use the fitting in the center of the tank to draw the fuel from the tank to the generator which has its own positive displacement diaphram type lift pump. To make up a rig for this, I will take a regular 1/4" compression fitting and drill it out so that the 1/4" copper line will pass all the way through it instead of butting up to the flange inside it. (already tried fitting it up it, works great!) This line will extend deep into the tank and stop about 4" from the bottom. It will be held in place vertically by the compressed ferrule.

The picture shows the tank and fittings and also the compression fitting before (lower left) and after(upper left assembly including nipple, tank, and fuel level).

 

[rmgill]

what's the fuel system on the genset? Because you could end up with back flow up the return from the main engine's fuel return line.

 

[OPCOM]

Patrick you can plumb the tank with one line and save a lot of trouble...

Install your fuel pump up by the gen set, tee the return line into the line before the pump... Use the 1/4 pipe outlet on top of the deuce's tank with a 90 degree fitting, drill the fitting and insert a piece of 1/4 hard line for a pick up tube, flux, solder and install...

This is what I have set up for my slave fitting in the back of my truck...

That would work for me if there was somewhere any trapped air in the line could go. With the genset having no slave connection or automatic slave fuel pump, it cannot expel the air if it is hooked up that way. So, I have to use a return.

 

[OPCOM]

what's the fuel system on the genset? Because you could end up with back flow up the return from the main engine's fuel return line.

The generator fuel system originally is a tank going by gravity to a diaphram type pump then to a filter then to the injection pump and to the injector. Bypass between the diaphram pump and the injection pump as well as bypass of the injector like on the deuce both go to a tee and back to the unit's tank. I do not think there is going to be a problem since the straight shot on the (added) tee from the truck's fuel return will go straight down into the tank where there is no back pressure and the generator's return is the 90 degree shot into the tee.

There is a pressure measurement on the truck IP somewhere maybe the return where there should be 6psi? but that is at the engine and this is right at the tank at the 'free' end of the truck's return line. I have not tried to measure any fuel pressure at the tee, I suppose I could temporarily attach a guage and see but I don't see how there would be much with only that little piece of "T" pipe there.

What I mean is that if the truck return line is for example 10FT long and has 6PSI at one end (pump bypass) and zero at the other(tank) end, then there would be a pressure gradient along the line of 6lbs/120inches (0.05psi/inch), or, at the top of the 2" tee assembly, (2/120)*6 psi, or 0.1 psi.

I realize this does not take into account the resistance to flow caused by the turbulence in the 90 degree fitting through which the fuel flow in the return line currently goes nor that inside the proposed tee, but I think these are minor enough to ignore -at least the issue with the 90 because that is before the tee.

My assumptions are based on the deuce return line dumping straight into the tank space, that is, no line inside the tank at the reurn inlet.

I am certainly no expert in fluid dynamics and welcome more comments.

 

[OPCOM]

did it.. all went smooth except the fuel return elbow fitting was extremely tight into the tank. It broke and I had to replace it. 1/4" copper line was used for the generator fuel supply and return. It's not very pretty now but the lines should be able to be dressed later.

The generator shelf was also made level within 1/4". Used a 5 ton jack under the low side to 'correct' the bent bracket. Later, allthread will probably be used to 'suspend' the outer edges of the generator shelf from the bed so it cannot wiggle. (The fuel tank is prevented from wiggling by its straps which fix the geometry of the brackets to the 90 degree angles of the tank.)

It has not been tested with the generator yet and I ran out of time so I have not checked to see how much if any fuel wants to come out of the genset return line by virtue of the truck's fuel return flow through the Tee fitting. Despite my own thoughts on it, I am concerned about because it was mentioned. I'd appreciate any accounts of this happening with sufficient pressure to cause a problem and what might have been done to eliminate the problem.

lessons learned:
1. do the work on the return line first. The tap placed into the center fitting to draw fuel out for the generator will be in the way of the tools and the generator return line otherwise.

2. For the supply line to the generator, the idea in the picture above with the drilled-out compression fitting works very well with the 1/4" copper line.

3. The quoted/labeled sizes for pipe and fittings are based on a bizzarre system invented by sadists and apparently having only arbitrary relationships to their actual dimensions.

 

[Armada]

Nice work sir! You are in the home stretch. Can't tell in the last photo, you may want to add a grommet in the hole where the lines come through the frame if theres not one already.

 

[cranetruck]

Looking good Patrick, it's amazing how these little projects stretch out in time and it makes one realize the amount of time spent on the original design details.
BTW, which thread sealer are you using? I have found that the yellow teflon (fuel resistant) tape is hard to work with since it's so thick and may go for a different solution.