Dual fuel tanks

[Gunzy]

I'm curious what is involved to put another fuel tank on a M923 on the right side where the rear tool box is (directly across from driver side tank).
Do they have pick up pumps in them?
Can I get away with just a switching valve and switch for sender?
Will a left tank mount to frame on right side with out modifying the frame?
If I am missing anything, what?
Thanks for any advice in advance.
Gunzy

 

[wreckerman893]

I'm curious what is involved to put another fuel tank on a M923 on the right side where the rear tool box is (directly across from driver side tank).

Do they have pick up pumps in them? No, the Injector pump pulls the fuel.

Can I get away with just a switching valve and switch for sender? If you are doing an addition I'd use the second tank as storage and pump the fuel to the primary tank when you need it. Some of the M818 tractors had such a system. If you want to pump out of the extra tank you will have to plumb the return line to it or you will over fill the primary and suck the fuel out of the secondary quick. The switching valve setup can have issues if the orings dry out. It will cause the system to suck air and cause a lot of headaches.

Will a left tank mount to frame on right side with out modifying the frame? Yes...you will need a set of mounting brackets. You might be able to use the tool box brackets but you will need to put something non-metal between the tank and bracket to prevent rubbing a hole in the tank.

If I am missing anything, what? You will need to either add another fuel gauge or wire the single one to monitor both tanks.

 

[jagman]

Would it be possible to borrow the idea that Ford used to use on their 94-97 powerstrokes? There is a dual tank setup and with a switch in the cab you can go from tank to tank. Maybe you can retrofit that system in place?

 

[cranetruck]

The 1969 5-ton xm757 came with a dual tank system. There were selector valves and a relay for the fuel gauge to indicate level in the tank that was selected..

 

[jesusgatos]

How does the dual tank setup in the M931/2 trucks work? Looks like the tank on the right is smaller? is that just because of the hydraulic reservoir on the winch trucks? If that's not in the way, couldn't you just add a second main tank?

 

[Gunzy]

I picked up a M932A2 and it has dual tanks. There is an electrical switch for the gauge and a mechanical lever/valve for the fuel lines that switches both the feed and return lines. I plan on using this system in my M923 to add a second 55 gal tank to the pass side where the rear tool box is. If it works in the M932 it should be fine in the M923.

 

[TacticalDoc]

I plan on doing 2 tanks on a M923. I'm going to make it simple by using an inline pump and in line filter from the spare tank to the primary tank.

 

[jesusgatos]

I want to keep the tanks and return lines separate so I can have on dedicated diesel tank and one slut-tank for oils and whatever I can get my hands on.

 

[TacticalDoc]

I want to keep the tanks and return lines separate so I can have on dedicated diesel tank and one slut-tank for oils and whatever I can get my hands on.

why would you want one for oil? I didn't think the 900 trucks were multi fuel.

 

[quickfarms]

On commercial trucks one tank is the primary, suction and return, and the second tank is an auxiliary. There is a valve on the front or back of each tank and a combination of hose and hard lines connects the tanks. This is a very simple setup that does not have the issues associated with a selector valve.

The 250 is not a multifuel engine.

 

[jesusgatos]

Dunno much about the 8.3 in my A2 yet, but the 12V 6BT Cummins tolerate alternative fuels pretty well, so if they're similar in that regard, then seems to me that the ability to burn gasoline in the multifuel engines is the only fuel option I'm really giving up.

 

[Gunzy]

NHC 250 and the 8.3 cummins should both be able to run about a 25% WMO/WVO mix in the diesel if it's been filtered. I am setting up a couple drums to filter WMO from for my NHC 250 as I can get as much as I want for free. Don't see using a second tank just for oil though when it needs to be mixed anyway. There are at least 3 ways of setting up a second tank that I have found but I figure if I have all the dual tank parts from a M932 I may as well go that way.

 

[jesusgatos]

25% huh, is that it? If that's true, then yeah I agree, hardly worth the trouble to isolate tanks.

 

[73m819]

On commercial trucks one tank is the primary, suction and return, and the second tank is an auxiliary. There is a valve on the front or back of each tank and a combination of hose and hard lines connects the tanks. This is a very simple setup that does not have the issues associated with a selector valve.

The 250 is not a multifuel engine.

This is sorta wrong, on OTR dual tank setups, there is a CROSS OVER hose between the two tanks, the truck drews out of only ONE tank but both tanks are connected so they are at the same fuel level, the shut off valves are there incase there is a tank/cross over leak (wreck, ect.), the leak will NOT drain both tanks.

The 39 series 5ta2 dual tank setup drew out/returned to the LEFT tank and had a transfer pump drawing out of the right tank, pumping to the LEFT, also along with the transfer switch/indicator, there was a fuel gauge L/R selector switch on the dash

 

[TechnoWeenie]

Didn't want to start a new thread when this was so close in topic, albeit older..

Thinking of doing the same thing on my M934...

Why not just run a line at the bottom edge of the tank to the other tank at the bottom edge of the tank?

The fuel level will self adjust, no worries about pumps, or weight distribution, as both tanks will always have the same amount (generally) in them....

Am I missing something?

Seems a simple shutoff valve on each side and a 1/2 or 3/4" line from one tank to another, should be adequate.

 

[Section8]

I was thinking similar. I used to have a Dodge 1 ton that had two tanks with a simple cross over. Fill one tank and the other fills as well and balance out. No need for extra fuel gauge wiring and pumps.
Why would that not work on any other trucks. Unless you have a multifuel and want a dedicated tank for slurry fuel.

 

[DaveP]

I was thinking similar. I used to have a Dodge 1 ton that had two tanks with a simple cross over. Fill one tank and the other fills as well and balance out. No need for extra fuel gauge wiring and pumps.
Why would that not work on any other trucks. Unless you have a multifuel and want a dedicated tank for slurry fuel.

one of the biggest problems with crossover lines is snagging them on something and ripping them off.

 

[ke5eua]

one of the biggest problems with crossover lines is snagging them on something and ripping them off.

The het and the 5 axle pls has dual tanks. Simple cross over line connection.

I'm adding the cross over line to my 818 tanks, going to put something under it to protect it.

 

[98G]

Why run it accross the bottom where it can snag? Run it from the top, with the pickup continuing to the bottom of the tanks. Prime it once, and after that as long as you don't run it dry the siphon effect will lift the fuel and keep the levels equal in both tanks.

 

[tennmogger]

Commercial OTR trucks are always level. Our Mil trucks were made to be tilted during offroading (some as high as 45 degree), and maybe even parked at large angle of tilt. In those cases the lower tank can overflow, and the upper tank starve for fuel. For those reasons the crossover might not be a good idea.