MEP 802A Aux Fuel Pump

[Coley]

I have an 802A I am working on that will not run the Aux pump. I have replaced the aux pump float, and checked that the pump itself works. I have also replaced the little box with the circuit board in it that is inline after the float. I am running out of ideas. The gen set has an autostart installed and had been working great since Oct. The aux pump will not come on either running with the autostart or setting the start switch to run / Aux manually. Any suggestions?

 

[Gunzy]

If the Daytank is full it won't operate.

 

[Coley]

Day tank is empty when I am testing it. I have the owner run till the low fuel shut off happens before I work on it.

 

[cuad4u]

You said you replaced the float and tested the aux pump among other things. When the day tank is empty the float will call for fuel. Are you getting 28V to the aux pump? If you are it HAS to be a defective pump. If not I would start back tracking from the pump until you find 28V.

 

[Guyfang]

Do you have voltage on pin 5 of the S-1 start switch when the switch is in the Aux position? Have you checked out K19?

 

[Coley]

I will check the voltage. What is K19?

 

[Guyfang]

K-19 is a relay. Do you have the tech manuals for the generator?

 

[Coley]

I do. A printed one but am unsure where it is. I'll grab a PDF.Thanks

 

[Guyfang]

TM9-6115-641-24 has the schematics in the back. For a better copy, look in the SS manuals section for a file I posted with enlarged schematics and color coded schematics.

 

[Coley]

Ok, I have the color diagram. getting power out of terminal 5 on S1. All seems to check out OK for the Module, Aux Float, and pump. I swapped the relay R19 out with another and still no dice. What does the regular low level float switch have to do with the Aux system? From the diagram it appears to be tied in somehow. I'm not that great with wiring diagrams.


Coley

 

[Guyfang]

When the S-1 switch is in AUX position, the low fuel level switch, FL-1 tells the K-19 fuel level relay to do its thing. That means the AUX fuel pump turns on to replenish the fuel in the fuel tank. When the FL-1 contacts open, (no more low fuel level situation) then the AUX fuel pump turns off, preventing the tank from being overfilled.

 

[Coley]

When the S-1 switch is in AUX position, the low fuel level switch, FL-1 tells the K-19 fuel level relay to do its thing. That means the AUX fuel pump turns on to replenish the fuel in the fuel tank. When the FL-1 contacts open, (no more low fuel level situation) then the AUX fuel pump turns off, preventing the tank from being overfilled.

I thought thats what the Aux float switch did??Coley

 

[Guyfang]

Your right, I meant FL-2 contacts and K-15 relay!! Its late. Didn't get much sleep last night as I was at a concert until 02:45 and then it was two hours getting home. Sorry!!

 

[Guyfang]

The Auxiliary Fuel System consists of an external fuel supply, piping, fuel filter, a 24 VDC auxiliary fuel pump and
a fuel level float switch. When the MASTER SWITCH is set on PRIME & RUN AUX FUEL it actuates the auxiliary
fuel pump and transfers fuel from the external fuel supply to the generator fuel 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.
The FUEL LEVEL indicator indicates fuel level of generator fuel tank from (E) empty to (F) full in quarter tank
increments

This passage is from the -10 manual.

 

[Coley]

From the diagram FL1 looks like it is tied in somehow also?


Coley

 

[Guyfang]

FL-1 tells the A-9 that the tank is full. The A-9 is what tells the E-1, (Aux fuel pump) when to turn on, but only when the S-1 is in the Aux position. When the S-1 is in the run position, terminal 5 on the S-1 is without voltage. So even when the FL-2 tells the A-9 to turn on the Aux pump, it will not turn on.

 

[Coley]

OK. got it. So I need to check out FL-1 as well. Thanks!

Coley

 

[Coley]

FL 1 float is reading as it should. Ohms are within limits for empty and full positions. The fuel gauge on this generator is not working. It has not been working but it seemed not to cause any issues before. Could this have something to do with the problem?

Coley

 

[Daybreak]

Howdy,
Since I am in a similar predicament.

What distance approx. should the top be showing above the locking nut gasket?

I do not have a good reference since it was messed with. I have taken it out, and verified it is working. I put in a new cork gasket. I just need a idea of where to set the height. The manual talks about the fuel level indicator being .15" off the bottom.. Just not this one for the aux fuel pump off/on and no-fuel error.

I need to do some fuel draining and filling to see where I get power to the pump. I found it is easier to just unplug each pump and wait until I see the 24 volts being pushed, since I want to ensure it will fill when low, and shuts off properly before overfilling.

 

[Daybreak]

Howdy,
Nevermind. Going back and forth reading to many TM's
Here it is.

Set float switch stem 1/16 inch from bottom of fuel tank . Tighten switch plate adjusting nut. Connect electrical connector and remove tag. Install front housing panel, paragraph 2-18.4. Connect negative battery cable and close access door