MEP-803 Aux Fuel Circuit

[StVeronus]

Trying to get my generator to run off of my auxiliary fuel drum. After the unit is running, I switch it to Prime & Run Aux Fuel but the pump doesn't turn on. So I removed the tank cover metal to expose the Aux pump. I unplugged the power connector and put my DMM on there, but it showed no voltage. Does anyone know where on the circuit panel I should probe next to see if power is going to the unit from there? I don't mind running my own wires to jump it if I can figure out where the aux pump connects at. I would just put it on a 24v source, but it needs to shut off when the tank gets full. I guess I can test by jumping power to it to make sure it turns on. Thanks guys.

 

[AfghanVeteran2010]

Whats the fuel level on tank? Is it full. The MEP-803a if not all MEP's runs off the the day tank. The AUX fuel system maintains the fuel level on the day tank. The fuel level float switch shuts off the auxiliary fuel pump when the generator fuel tank is full and reactivates the pump as the level drops. I highly recommend that you download the TM for your set and read it cover to cover. The TM are on the forum in the TM section.

 

[Haoleb]

If you would like to test the aux system take the fuel cap off the tank and pull out the metal strainer tube. Inside the tank to the right is the float switch assembly. You can reach in there and manually move the top float switch up and down to turn the pump on and off.

When I did this I unplugged the main fuel pump so that the only noise I would hear is the aux pump coming on.

 

[StVeronus]

Thanks for the input guys. I removed the cover and can feel the pump turn on. So I pulled the filter and it wasn't clogged or dirty. I'm guessing it isn't pulling enough out of the drum to fill the tank. I will try putting some fuel in a smaller container that I can see if/how much is getting pulled.

I'll update with the findings.

 

[jamawieb]

Thanks for the input guys. I removed the cover and can feel the pump turn on. So I pulled the filter and it wasn't clogged or dirty. I'm guessing it isn't pulling enough out of the drum to fill the tank. I will try putting some fuel in a smaller container that I can see if/how much is getting pulled.

I'll update with the findings.

The TM says you should get a minimum of 32ozs with the pump running for 1 minute.

 

[gstboy69]

Whats the fuel level on tank? Is it full. The MEP-803a if not all MEP's runs off the the day tank. The AUX fuel system maintains the fuel level on the day tank. The fuel level float switch shuts off the auxiliary fuel pump when the generator fuel tank is full and reactivates the pump as the level drops. I highly recommend that you download the TM for your set and read it cover to cover. The TM are on the forum in the TM section.

Thanks for the information. I THINK Thats the reason of my mep 803a don't start with the Aux tank,I remove all the diesel from the daily tank and the fuel lights always on and don't start. Tomorrow I fill the tank a half crossing my fingers she started. I have auto started board with ATS.

 

[vprinc]

Hello everyone. I’ve been trying to figure out an issue with my Mep-803a auxiliary fuel pump. I have the generator mounted on a trailer with a 75gal semi tank on the back. I have an auto start card installed with the aux fuel jumper set on and the 2 wire running to my inverter. This configuration has worked for over 5 years. The other day I lost power. When I investigated the issue it turns the generator was out of fuel. After looking deeper it turns out that the aux pump was constantly running and I basically put 75 gallons of diesel on the floor.
here is what I have done so far. Checked continuity on the float valve and it shows continuity. Verified that of if I put the S1 switch into prime run position aux pump turns off. Pulled all relays one at a time but pump continued to run when S1 was in run/aux file position. Any ideas as to where to look next?
Thank you in advance for your help.

 

[kloppk]

I'd suspect the A9 Aux Fuel mode failed causing the Aux Pump to run continously.
The sucker's do fail. I've repaired a number of them.

 

[vprinc]

Sorry. What’s the A9?

 

[kloppk]

It's a small module about 2" x 2" located to the right of the fuel tank. It reads the float switch's and controls the Aux Fuel Pump and the Low Fuel fault circuit.

 

[vprinc]

Do we have a part number? Can I still get them?

 

[kloppk]

The info is in the -24P TM
88-20492
NSN 6680-01-392-8821

If you like you can ship it to me. I can test and repair it for a nominal charge.
PM me if you decide to go that route.

 

[m32825]

I'd suspect the A9 Aux Fuel mode failed causing the Aux Pump to run continously.
The sucker's do fail. I've repaired a number of them.

I use the aux pump to fill the day tank but I have trust issues, so I don't leave the switch in that position all the time. If the house is on generator I'll be around anyway, topping up a couple times a day is not a problem.

 

[vprinc]

Yea I can’t do that. I’m not up there full time so its my backup to my solar so it has to be auto fill.

 

[vprinc]

The info is in the -24P TM
88-20492
NSN 6680-01-392-8821

If you like you can ship it to me. I can test and repair it for a nominal charge.
PM me if you decide to go that route.

I tried to PM you but I keep getting a message to start a conversation with a staff member cataract? Anyway. If you can email me that would be great. v_princip@me.com.

 

[kloppk]

I'll send you an email

 

[Ray70]

I tried to PM you but I keep getting a message to start a conversation with a staff member cataract? Anyway. If you can email me that would be great. v_princip@me.com.

FYI, there is a minimum number of post required on your account before you can send a PM without the help of a moderator. Since you're new you're not able to send PM's directly on our own yet.... all in due time!

 

[kloppk]

Damage to vprinc's A9

 

[2Pbfeet]

Yeah, that qualifies as unhappy silicon in my book. Ouch.

@kloppk thanks for sharing the photo!

All the best,

2Pbfeet

 

[kloppk]

That's the component that switches the power on and off to the Aux Fuel Pump. Usually it fails Open preventing the Aux Pump from operating.