MEP 802A Aux fuel. Thoughts on bypassing system and installing a tiger loop?

[Coley]

I have 2 MEP 802a sets I have installed for people who want to use the AUX fuel. Both are problematic right now. One the aux pump is not coming on, and the other the aux pump shuts off too late overfilling the gen.

My solution I think I am going to do is plumb a tigerloop into the system and completely bypass the tank / aux pump setup. The Tiger loop has 3 connections, line in from tank, line out to main fuel pump, and an inlet for return fuel. The Tiger Loop would be installed in the fuel area at the rear of the gen. Inlet line would be plumbed, then outlet to the fuel pump, then the return line plumbed into the loop. Tank would be left with a couple gallons in it to keep from low fuel shut down and any hoses plugged.

I have the tiger loops coming from Amazon, ($100 each) and plan on doing this on one of the set this week. An added benefit to this is the fact I now will have a backup fuel pump if the main goes out. Anyone see any glaring errors in my solution?

CF

 

[Daybreak]

Howdy,
It sounds like the mechanic before you got into the fuel tank and moved your fuel sensor. That could be as simple as opening the front panel, loosen the locking hold down ring and lowering the fuel level sensor.

Auxiliary fuel all relies on the fuel level sensor for turn on aux pump and shut off aux pump. It is the upper float which is the aux level switching.

 

[Korgoth1]

Anyone plumb the 80x series directly, bypassing the lift pumps entirely? It worked great on my old 004.

 

[Coley]

Howdy,
It sounds like the mechanic before you got into the fuel tank and moved your fuel sensor. That could be as simple as opening the front panel, loosen the locking hold down ring and lowering the fuel level sensor.

Auxiliary fuel all relies on the fuel level sensor for turn on aux pump and shut off aux pump. It is the upper float which is the aux level switching.

Honestly I have tried everything. Just had 4 Army Gen Mechs out last weekend to look at it and they were baffled. I am done troubleshooting it. A system like what I am going to do plumbed into a 500 gal tank with one point of failure (the main pump) seems OK to me. Gen will never be moved, and should run good that way. I will be eliminating a lot of stuff that could cause me problems.


CF

 

[cuad4u]

The MEP 003A that I kept for my personal use is mounted on a military trailer with a 100 gallon aux fuel tank. I do not use the built in 13 gallon fuel tank at all. In fact it was removed and installed on another 003A. I re-plumbed the fuel suction hose so the two pumps that normally operate the generator "suck" fuel directly from the 100 gallon tank. The only other thing you have to do is connect the fuel return hose to the 100 gallon tank. This set-up will give 100-130 hours of run time before the 100 gallon tank has to be refilled. Fortunately none of the power outages have lasted that long. I keep around 1000 gallons of red diesel fuel on the farm to run tractors etc, so refilling the 100 gallon tank is not a problem.

 

[Korgoth1]

The way the 004 worked, my fuel oil tank was on a stand, higher then the day tank, so it drained into the unit without needing the pumps.

If the 802/2 aux lift pump will allow fuel to flow through when off(they should) then simply having the aux tank above the day tank will bypass the aux lift pump.

To bypass the prime lift pump, you would have to bleed the lines very well because I could see that setup airlocking very easily. I would hook the aux tank line to the line that hooks to the outlet of the prime pump, I would hook in the fuel return line from the injectors to the aux fuel tank line using a T. I believe that is all the tigerloop does anyway.

Another note, would be wise to have one of the fire shutoff valves on your aux tank, so you can shut fuel off if there is a leak, and also if there were a fire it would shut itself off.

 

[DieselAddict]

If the 802/2 aux lift pump will allow fuel to flow through when off(they should) then simply having the aux tank above the day tank will bypass the aux lift pump.

There is no fuel cutoff solenoid for the AUX fill on the 8xx machines. If you gravity feed your AUX source it will overflow the tank in the generator.

 

[Korgoth1]

It has not so far... I will keep an eye on it though. The pumps must not be the 'flow through' design the old 004 was.

 

[DieselAddict]

You may be fine if you don't put the AUX tank up too high. I have seen one report recently here on the forum where an elevated AUX supply resulted in a fuel spill on the generator from an overflow.

 

[Korgoth1]

Thats good to know, mine is only 2' higher, plus the head pressure of the tank. My prime pump has quit working, so I have an opportunity to test out the tiger loop idea.

 

[Korgoth1]

It works good. Not hard to bleed either.

 

[peapvp]

I thought I bump this

 

[peapvp]

On all the 800's it is a good idea to inspect the float switches periodically. The low limit can get stuck as well and then the Genset is going to run dry.
The Fuel Sensor Sending Unit are a doomsday's scenario as well, but normally affect only the Fuel Gauge, making one believe that there is more fuel in the tank then what is available.

 

[Ray70]

I'd be curious to hear the results....
The OP's issue definitely sounds like a float issue, but I'm also curious about the tiger loop scenario.
I'm curious to see how a tiger loop works when fed with a pump.
I put a tiger loop on my boiler but it is suction fed from the burner pump, not force fed from a pump at the tank.

Also wondering about gravity feeding a 802/803. The 004 is essentially a gravity feed fuel system, the 802 /803 is not. I think it will be dependent on head pressure. My experience with those metering pumps has been that they require a few psi to operate, so the top of the fuel in the tank probably need to be at least 6-8' higher than the pump.

This gravity feed system may eliminate any potential pump failures, but I would much prefer a suction system with no risk of leaking fuel everywhere in the event of a hose , connection or other failure, Just keep a spare pump on hand.... much cheaper than the hazmat clean-up cost if you loose your entire tank.

 

[kayak1]

On all the 800's it is a good idea to inspect the float switches periodically. The low limit can get stuck as well and then the Genset is going to run dry.
The Fuel Sensor Sending Unit are a doomsday's scenario as well, but normally affect only the Fuel Gauge, making one believe that there is more fuel in the tank then what is available.

Will running an 800 dry harm the genset?

 

[Ray70]

Normally the low fuel float will shut you down before running dry, but if it is stuck and the machine runs dry nothing will get damaged. Fill the fuel, then run the pump on prime/run for a while and it should re-prime it and push any air back to the tank allowing it to restart.

 

[peapvp]

Will running an 800 dry harm the genset?

I don’t think so, but you will have to re pressure rise the IP etc.
Just time consuming.

 

[Light in the Dark]

As Ray said, its a self priming system. Just gotta let the system push the air out, and maybe crank it over to get any air out of the hard lines. Not really a concern.