Duel Diesel Tanks

[Kim and Ed Kreyling]

Yesterday I bought a 2020 Magnitude BB35. It has duel Diesel Tanks (Front and rear). I have let the rear tank go all the way past 1/4 tank and it never switched to the Front tank. According to the main fuel gauge I have twice the ranges I am getting on the rear tank. Does it switch automatically? At what point? Is there some owner operated control of tank choice? I’ve asked these questions of my techs and salesmen. No one has a clear answer. HELP!

The Chassis is a 2019 Ford F550 XLT Diesel.

[Judge]

I have a 2020 Magnitude SV34 on a 2019 F550 chassis with the dual tanks as well.

It is my understanding that the tank switching is automatic.

I have monitored my tanks and the way mine seems to work when both tanks are full is.....

- Fuel starts being drawn from the front tank.

- After the front tank has drawn down to about 3/4, it switches over the the rear tank.

- When the rear tank gets down to about 1/4, it stays drawing from the front again.

I have not had the main gauge drop below 1/4 tank so far before refilling.



After I wrote this I did a quick search and I came up with this online from a Ford Tech. Based on the description of your situation, you may want to talk or take it to a Ford Commercial Service Center. Sounds like the valve to the rear tank is staying open / stuck open all the time and the rear tank is always draining to the front tank.



Dual Fuel Tanks (If Equipped)

Your vehicle may have a dual fuel tank
delivery system which operates
independently and automatically.

The fuel pump in the front fuel tank delivers fuel to the engine. When the fuel level in the front fuel tank drops below three quarter full, fuel automatically transfers from the rear
fuel tank to the front fuel tank.

Whenever there is fuel in the rear fuel tank, the front fuel tank level remains between half and three quarter full.

Note: If your vehicle runs out of fuel, you must add fuel to the front fuel tank to restart the engine.

[ratherbboatn]

I have a similar question about the 2 diesel tanks. It feels my front tank runs the Onan Diesel Generator and the rear tanks runs the F550 truck. The gauge in the truck gives me levels for both but also averages them in another gauge. I've been considering adding a diesel additive but concerned it wouldn't be good for the generator. I'd love to know exactly how this works. I'll keep investigating and get back to you.

[ratherbboatn]

Actually just talked to Thor Motor Coach customer service. They said both diesel tanks are hooked together and they do auto switch/share fuel. The diesel generator will auto-shut off when that tank gets to 1/4 level. I also asked about adding an additive to both tanks and he recommended doing that. I'm going to try Power Service DIESEL KLEEN +CETANE BOOST.

[EA37TS]

Originally Posted by ratherbboatn

Actually just talked to Thor Motor Coach customer service. They said both diesel tanks are hooked together and they do auto switch/share fuel. The diesel generator will auto-shut off when that tank gets to 1/4 level. I also asked about adding an additive to both tanks and he recommended doing that. I'm going to try Power Service DIESEL KLEEN +CETANE BOOST.

What does the Onan generator manual say about using additives? Screw up the penny and you might be stuck with an expensive repair bill. Thor is not Cummins Onan and Thor does not warranty the generator.

[ducksface]

I'd do a LOT of research before I would follow the advice of a phone clerk at a company which has NOTHING AT ALL Ever to do with a Ford diesel engine. You truly, truly, might as well be calling a clerk at Walmart to ask the same question.
Nothing against Thor, but you might have well have asked surgical advice.

An additive won't hurt anything but potentially your warranty.
I'd read up on that.
And
Why the additive?
And
Divide additive cost by miles.
It might negate the supposed monetary savings of diesel.

[ratherbboatn]

Thanks for the great questions and follow up! I did go to each of the specific manufacturers on each. Cummins Onan said it wouldn't be a problem w/ the generator just use a good brand and follow the instructions. I then investigated the Ford manual and it does say an additive shouldn't be necessary, however if you suspect low levels of cetane at the pump then you should use Motorcraft cetane booster or an equivalent cetane booster alternative.

Hard to know what you are getting at the pump. Will keep a little on hand but might try to go w/o for now.

[Travelin' Texans]

Most diesel additives have a bacteriacide along with anti gel agents which would be good for any large amounts diesel fuel such as dual tanks. The additives also add extra lubricity which is necessary when using ULSD nowadays. Some have cetane boost which if you think it helps use it, but doubt you'll notice any performance or mileage differences.
Power Kleen, Howe, & Lucas are all good choices & should have no effect on your warranties for truck or generator.

[powerboatr]

Originally Posted by ducksface

I'd do a LOT of research before I would follow the advice of a phone clerk at a company which has NOTHING AT ALL Ever to do with a Ford diesel engine. You truly, truly, might as well be calling a clerk at Walmart to ask the same question.
Nothing against Thor, but you might have well have asked surgical advice.

An additive won't hurt anything but potentially your warranty.
I'd read up on that.
And
Why the additive?
And
Divide additive cost by miles.
It might negate the supposed monetary savings of diesel.

yes because we can safely bet thor did NOT mess with the factory fuel flow or supply system. today's systems have to meet safety rules and thor is not about to redesign a system



i find the ford system pretty interesting to use fuel to one level then transfer fuel forward to keep front tank mostly full, is there a light or indication that the rear tank is now empty and cannot transfer fuel forward?