MEP-802a auxiliary pump: any chance fuel can siphon from 30 gallon drum?

[hammick]

I have seen speculation about diesel siphoning if using the aux fuel pump with an aux fuel tank that is too high. I am planning on using a 30 gallon plastic drum as my aux tank with the military bung adapter as the fuel pickup. Obviously I would thoroughly test this while present but my plan if to have the genset autostart when I am not present to charge my solar batteries.

Has anybody had first hand experience with the aux fuel pump siphoning and filling the main tank to the point that fuel spills on to the ground?

Thanks.

 

[Zed254]

The Aux Pump switch hung on my 802 one time and overfilled the on board tank. I now only do Aux refills with me standing by the machine. Same machine has had 10 or more successful refills since that 1 overfill but I prefer my diesel in the tank.....and I have trust issues.

 

[hammick]

The Aux Pump switch hung on my 802 one time and overfilled the on board tank. I now only do Aux refills with me standing by the machine. Same machine has had 10 or more successful refills since that 1 overfill but I prefer my diesel in the tank.....and I have trust issues.

Yikes. Did it spill out the fill cap or is there an overflow tube?

 

[Zed254]

Yikes. Did it spill out the fill cap or is there an overflow tube?

Where the fill tube attaches to the tank. Fuel seeped out of the bottom of the compartment, into the engine compartment and outside the enclosure. I caught it after a quart or so spilled. That's why I monitor Aux filling.

 

[robson1015]

I have been siphoning from a 55 gallon barrel with no issues....

 

[98G]

I have been siphoning from a 55 gallon barrel with no issues....

Is your barrel higher than the fuel tank?

 

[98G]

I have seen speculation about diesel siphoning if using the aux fuel pump with an aux fuel tank that is too high. I am planning on using a 30 gallon plastic drum as my aux tank with the military bung adapter as the fuel pickup. Obviously I would thoroughly test this while present but my plan if to have the genset autostart when I am not present to charge my solar batteries.

Has anybody had first hand experience with the aux fuel pump siphoning and filling the main tank to the point that fuel spills on to the ground?

Thanks.

Let me emphasize and clarify what I think you're really asking: "when filling with the aux pump and the pump shuts off, is the pump sealed against passive flow of diesel past it?"

Given that your 30 gallon drum is higher than your genset, the aux pump will serve to prime the line and get fuel flowing passively. Unless the aux pump serves as a shut off valve, fuel will continue to siphon even after the aux pump shuts off.

My best guess says the pump will probably allow fuel to flow past it, and having your aux tank higher than your genset is a recipe for a puddle of diesel on the ground. But it's just that, my best guess.

 

[hammick]

My barrel will be on the concrete floor and so will my genset. What is the important height measurement, the pickup tube or the height of fuel line connection to the barrel? Pretty sure my pickup tube will be lower than the genset aux fuel connection but the top of the barrel will be higher.

 

[hammick]

Let me emphasize and clarify what I think you're really asking: "when filling with the aux pump and the pump shuts off, is the pump sealed against passive flow of diesel past it?"

Given that your 30 gallon drum is higher than your genset, the aux pump will serve to prime the line and get fuel flowing passively. Unless the aux pump serves as a shut off valve, fuel will continue to siphon even after the aux pump shuts off.

My best guess says the pump will probably allow fuel to flow past it, and having your aux tank higher than your genset is a recipe for a puddle of diesel on the ground. But it's just that, my best guess.

That is exactly what I am asking. Do you think the aux pump has enough suction to open a check valve?

 

[kloppk]

Not sure the pump would have enough oomph to open a check valve. Plus it would put a strain on the pump all the time it's running.
You could always add a 24 VDC solenoid valve and trigger it to open when the Aux pump kicks on.

 

[hammick]

I have been siphoning from a 55 gallon barrel with no issues....

Are you using the bung adapter on top of the barrel with the threaded copper pickup tubes?

 

[98G]

My barrel will be on the concrete floor and so will my genset. What is the important height measurement, the pickup tube or the height of fuel line connection to the barrel? Pretty sure my pickup tube will be lower than the genset aux fuel connection but the top of the barrel will be higher.

The important height measurement is the height of the top of the fuel in the barrel compared to the height of the first place it can leak out of the receiving tank.

 

[DieselAddict]

The pump itself is very much like a check valve inside. Its a mechanical plunger that is moved by an electromagnet. If your fuel pressure is higher than the plungers spring tension then it will push through the pump. If the plunger gets stuck it can let fuel flow thought it.

The pump will self prime within a few feet. I have my doubts that it will reliably draw through a check valve that has any significant tension on it (cracking pressure).

The best setup is to have the fuel supply slightly below the generator so if yo have any failure of the AUX pump it doesn't overflow the day tank.

Edit - I can report that the pump will self prime with the fuel 4' below the generator.

 

[Guyfang]

Where the fill tube attaches to the tank. Fuel seeped out of the bottom of the compartment, into the engine compartment and outside the enclosure. I caught it after a quart or so spilled. That's why I monitor Aux filling.

The leak was the rubber boot not being on right, or the clamp was loose. If any of you ever move your gen set, or its trailer mounted and you drove someplace, and you find fuel in the bottom of the set, that were its coming from. The boot is loose, or not on right. Very common problem

 

[hammick]

Edit - I can report that the pump will self prime with the fuel 4' below the generator.

Thanks Chris but does that mean that fuel will/can bypass the aux pump and overfill the main tank?

 

[DieselAddict]

Thanks Chris but does that mean that fuel will/can bypass the aux pump and overfill the main tank?

It is possible if the fuel level is above the AUX pump. If the pump is in good shape the spring in the pump should push the plunger against the seat and prevent it from passing fuel.

If the AUX fuel supply is below the tank in the generator that can't happen.

 

[robson1015]

I believe the military use of the 803 included connecting auxiliary fuel line to a 55 gallon drum of diesel fuel. Please correct me if I'm wrong.

 

[Guyfang]

I believe the military use of the 803 included connecting auxiliary fuel line to a 55 gallon drum of diesel fuel. Please correct me if I'm wrong.

I have used AUX to suck fuel from:

2.5 ton truck
5 ton truck
Hett truck
4K fork lift
1200 gal fuel tanker
6000 gal fuel tanker
another gen set next to the one running
5 gal fuel can
55 gal fuel can
600 gal fuel pod
500 gal fuel bladder
1000 gal fuel bladder
600 Ltr hand pumped full, fuel tank 3 meters above my gen sets.
10,000 Ltr in the ground fuel tank
my car

Could go on, but you get the picture

 

[m32825]

I ran my 803a with an aux connection to a 55 gallon drum for the first time a couple weeks ago. Drum fuel level was a foot or two above the top of the generator. Ran the tank pretty low, turned to the aux setting to top it back up, filled tank, put switch back to normal run position, no problems there.

Came back an hour later and the tank was reading higher than before. Hmm, I thought, maybe the needle was a little stuck before and now it's reading correct? Came back an hour later and there was about a quart of diesel on the driveway. What?!?

I pulled the fuel cap and it was filled all the way to the lip. Removed the end panel around the fuel tank fill port to verify that the aux pump was off. It was. Fuel was weeping out at the top of the fuel level sender.

Broke the connection at the drum and everything back to normal. My unit has an aftermarket fuel pump in it. I think you have to test your setup to find out for sure.

-- Carl

 

[Guyfang]

That's the problem with after market parts. Unless you see a data sheet, there could be surprises.