MEP803a Auxiliary Fuel Operation

[impi]

I have read through the TM and Operator manuals for the 803 and could not find a clear answer on the operation of the auxiliary fuel supply function. I was fortunate to have received the supply line with my unit when I bought it at auction and I purchased the jerry can adapter to go with it. I have a two 55 gal lined drums which I use for reserve capacity for when hurricane season gets busy (fuel supply always seem to be an issue).

I did a test run over the past two days and ran the unit for around 25 hours. I noticed the fuel level on the gauge dropped from near full to around 1/4 tank and then bounced up again to about 1/2 tank and down to 1/4 tank and back up to 1/2 tank. I understand that the auxiliary feed pumps fuel into the day tank. What I'm unclear about is whether or not the aux function would fill up the day tank or does it just add to around 1/2 tank before it stops - I understand that the aux function is triggered by a float switch, and not the fuel level float.

Any feedback will be greatly appreciated.

I'm testing the setup and would like to get all the quirks sorted before hurricane season shows up - don't want any surprises when I need the equipment to function.

Regards

 

[Farmitall]

Page 1-10 Change 1 of the 24 manual says the aux fuel pump shuts off when the day tank is full.

I've not run any external fuel supply on either of my 803a sets so I cannot comment on how full they fill the tanks.

There is is a test procedure for the float switch module in the manual and you can reach inside the tank and feel the two floats and see if they move freely.

 

[dav5]

My 803a cuts in at about 25% and cuts out at 80%. Adjusting the float should change the settings

 

[Daybreak]

Howdy,

The fuel level when it kicks on and kicks off is a variable from machine to machine. The float which controls the kick on and off can be installed at slightly different heights. It is suppose to kick on at around 25% and kick off at around 75%.

The best way to test it out quickly is to have a siphon handy. Have you generator operating and hooked up to the aux fuel, and selected on the S-1 switch. Siphon a bunch of fuel out of your generator and watch when the aux fuel pump kicks on, stop siphoning, watch for when it kicks off.

Yes, you can also manually reach into the fuel tank and manipulate the float and watch and listen to when it kicks on and off.

You obviously do not want it to run out of fuel, and you do not want it to overfill, and keep filling after its full.

 

[Guyfang]

One thing to keep in mind. When using the Auxiliary fuel function. The fuel filter referenced here, is the tiny, round "filter" that is screwed into the Aux fuel pump. It is NOT going to separate water from the incoming fuel. It WILL stop up quick, if the fuel is funky. And that's its job, to stop up and protect the fuel pump. So if you use Aux fuel function a bunch, DO think about replacing it, if your aux fuel supply is not real clean.

Most folks pull out the tank strainer when refueling with a 5 gal can. The screen is there for a reason. So do not get in a hurry when refilling the gen set tank.

 

[Keith_J]

Keep your fuel dry! The lip on drums is enough to trap rain and it will get sucked into the drum regardless of how tight you have the bung and vent. They also rust fast. Most diesel has biodiesel in it, this holds water and this makes it cloudy. Check with a flashlight. There are products you can put into diesel tanks to absorb water, one looks like a sock full of beads.

 

[impi]

I treated the diesel with Stanadyne Lubricity and added Power Service BioKleen Biocide when I filled the one 50 gal tank. I have a diesel subcompact tractor which will be cycling the fuel and the tank will be topped off and the other one filled before the start of hurricane season. I strap the tanks to wooden pallets and use the tractor's forklift to stick them on the pickup truck to go fill them up. Having 2 separate tanks will allow me to go hunting for fuel if one runs out and we still have supply issues - but fortunately it seems that fuel stations get up and running within the first few days after a disruption. Once the season is over I just gradually burn down the remaining fuel and get fresh fuel when it's time. The fuel are stored out of the sun undercover and dry.

 

[Buickrat]

From what I read in the TM, the aux pump should keep the day tank at 3/4 full. Mine comes on at a little over 1/2 tank and stops at 3/4.

 

[Chainbreaker]

Keep your fuel dry! The lip on drums is enough to trap rain and it will get sucked into the drum regardless of how tight you have the bung and vent. They also rust fast. Most diesel has biodiesel in it, this holds water and this makes it cloudy. Check with a flashlight. There are products you can put into diesel tanks to absorb water, one looks like a sock full of beads.

He's right about water infiltration over time. This might be worth considering if you store fuel in 55 gal drums exposed to elements:

https://www.absorbentsonline.com/55-gallon-drum-covers-tops.htm

 

[impi]

So I figured the fuel gauge was up to no good as far as it's readings were concerned. Traced it to a faulty fuel sender.

Replaced the fuel sender with a KUS USA SSS/SSL slide sender which I got from Dusky Marine.
http://www.duskyonline.com/WEMA-p-fuel-senders-withdraws.html#prod-chart

The old sender was rusted and grungy as ****.

While in there I pulled out the float switch and tested the switch for both triggering the aux pump and for the no fuel trip, both seemed to work fine. I noted that the switch was almost touching the fuel pickup line the way it sat in its mounting plate so I adjusted that it now sits with a bit more breathing room on either side so it doesn't come into contact with any of the other items in the tank. The aux pump now fills the tank to roughly 75%.

I confirmed the draw out of the 55 gal tank with a home made dipstick and the chart I found on the Sherwin Williams website for measuring tanks with dipsticks.

https://protective.sherwin-williams.com/pdf/tools-charts-list/drum_measurement_methods.pdf

Thanks for all the input. Everything is now serviced and ready for the season and spares has been acquired as needed (Filters, Fluids and a spare generic 24v fuel pump just in case.).

 

[Guyfang]

@Mweiss You are cross threading. Please stick to your established thread for this problem.