MEP804A--Anyone have one of these?

These units are fairly "new" compared to what I own--15KW, Isuzu 4cyl diesel & 3 phase.

Searched the forum but only came across 1 post & it just mentioned the 804A as a secondary item...Looking for owners of this unit...Is the engine any good? Noise levels? Can it be rewired to single phase? Fuel burn rate?

I just picked up a MEP-804A generator from Ft Bragg this week. It was in a group of 4 that went off with the highest hours 113 and the lowest 46. These are 3 phase only 120/208V 52 amps or 240/416V 26 amps @ 60 Hz up to 15 kW. I went and looked at all 4 before the auction. One had a broken main switch as the only visible problem with the rest OK. They even had the TM in a storage area in a side door still in the original plastic. All had been drained of all fluids and batteries removed (Isuzu liquid cooled 4 cyl diesel). I ended up with the 46 hour one and bought a couple of refurbished batteries on the way home. After replacing all fluids and connecting the batteries and putting in ~8 gal of fuel, I gave it a shot. I have a MEP 003A so I was used to hearing the aux fuel pump followed by the main fuel pump as the switch is rotated to prime and run. I heard the aux pump but nothing in the prime and run position. I hit the starter and only got a clicking noise behind the control panel. On the right side of the engine is a dead crank switch which will turn over the engine without ignition. I tried that and it would turn over and the oil pressure came up. After tapping on various things, the engine eventually cranked using the main switch but no ignition. I knew that the injector system had to be bled of air but the instructions did not show the transfer pump on this engine (mechanical) vs the electrical one in the TM. I figured out where the transfer pump was but saw no way to manually pump fuel. I eventually saw on YouTube a man bleeding his Isuzu truck engine and saw how the manual pump works. The mechanical pump has a cylinder on it with a cap that unscrews which then pops up so that you can pump until fuel comes out near the injector pump at a loosened nut. You then screw the cap back down and tighten the nut you loosened. After that, it cranked and runs fine. It is much quieter than the 003a! The TMs did not show the transfer pump installed or how to bleed it. I almost forgot to mention that liberatedmanuals.com had the applicable TMs for free. TM 9-6115-643-10 and -24

Robert

I just picked one up recently. Year 2000 MEP 804A. I am somewhat familiar with this unit but more so with the 803 A. Today I am running wire , conduit and installing the transfer switch for the 802 to my house. I have picked up a generator controller that will interface with the transfer switch for $375.00 from a supplier I use to repair bad circuit boards. If you have any other questions re your unit, I would be happy to help you along if I can and have others the I could bounce questions off if I cannot. (they are ex military who now work for in the service dept for a generator dealer).


As far as the 804, I would like to reconfigure this unit to single phase. Currently it is a 120/208 and 240/416 configuration.
MEP 804A, NSN 6115-01-274-7388, Ser FZ 58138. I would appreciate if you could point me somewhere for instruction to do so.

Thanks Mark

I ran my 804A this weekend to power one of my hot water/steam pressure washers. It needs 208V single phase so I used L1 and L2. Attached is a scan of the TM that came with the unit where it talks about single phase. It does note that the loads should be balanced when using single phase to avoid damage to the generator. I guess you should be able to get the rated amperage of 52A @ 120/208V or 26A @ 240/416V but I plan to use it for 3 phase power primarily.

Robert

I used my 804A this weekend to run my 208V single phase motor on my MX-2 steam cleaner. I used L1 & L2. Attached is a scan from the TM where it talks about single phase. It does warn to balance the loads to avoid damage.

Robert

My 804a quit running the other day. It sounded like it ran out of fuel, it started to surge and then it died. I first thought that the fuel had been stolen but not the case. I bought this unit recently with 46 hrs on it and had put on around 5 with no problems. As mentioned above, mine has a mechanical main pump (not the injector pump) that the TM does not discuss. I figured out how to bleed the air out as shown above and tried it this time. The pumping action did not feel solid as before and my attemp failed. I also noticed that I did not hear the aux electric pump running now as the main switch is cycled as I remembered from prior to my recent problem. I removed the pump from the engine and could see nothing obvious, a lobe on the injector pump drive mechanically drives the pump. I removed the manual pump cylinder (in the photo above my pen is pointing to it) and could not see a problem. On the side of the pump is a large flat nut (to the right of the pen and partially covered by a fuel line) that must be metric since it is between 1 1/8" and 1 3/16". I put an adjustable wrench on it last night and could not get it to budge. I'm going to try some heat when I get home. I found a schematic on the web. I am thinking that it may be some kind of check valve problem. I did make sure the feed from the tank was not stopped up. Any suggestions would be appreciated.

Robert

I took the fuel pump apart and did not see any problems. Reassembled pump and placed back on the engine. I tried to bleed the air out of the lines using the manual pump feature on the pump but did not feel solid pumping action. I used a fuel bulb to draw fuel through the pump and tried to manually pump again. This time, it felt better but not real solid but I did get fuel just prior to the injector pump. It started after about 15" of cranking and ran rough until the air was expelled and has now been running about 30 minutes. I still do not know what the problem was. On another note, I did not notice the electric aux pump making noise as the main switch was turned to start as I remembered in the past with a half full tank. After thinking about it, perhaps the aux pump does not run because the main tank is totally full as it is now?

Robert

It quit again after the above post. I really can't figure it out and the TMs do not talk about the Zexel mechanical transfer pump, just the electrical ones. I think my main problem lies with the hand pump (pointing at it with pen in a photo above). I took it off and can not see any way to take it apart. I turned it upside down and filled it with fuel before putting it back on the pump. I finally got fuel to come out of the injector return line while pumping the hand pump. It leaks badly while pumping so it probably has a bad o ring inside. It now runs but I am still unable to figure why it will start to surge and stop due to fuel starvation as it has twice in the past. So far, I have run it about an hour this time over several starts. The aux pump had stopped making noise after I totally filled the tank. I removed the aux float assembly. It has two round floats that slide over a tube. I wiggled them a bit and reinstalled the assembly. Now it works. I see no connection between the aux pump not working and the mechanical transfer pump getting air locked although they started at the same time. Do the MEP-803/2a gensets use this (Zexel) transfer pump?

Robert

Your probably sucking in air from that leaking hand pump. Try routing the hoses around the pump and see what happens.

I did actually think of that. The top of the pump that unscrews and pops up has a square type ring gasket underneath that should seal when screwed down. I made sure to get the top tight this time and it has worked so far. Perhaps before, I did not get it tight enough to seal.

Robert

the problem i see is that these are 3 phase only right? so if you run single phase you are just going to get 120-208 volts and use only 2 of the 3 windings, so you will only get a 10 kw genset. there is just no way around this if this is a 10 wire gen head as i assume it is. so without replacing the gen head ( a viable option ) you have gained nothing over a mep-803

That would be correct with it being 3 phase only power. To my belief there are a quite a few reasonable gains over the 803. My setup for the 804 is on a 3500lb civilian generator trailer with a 3 phase nema 4x breaker panel (from my neighbor). I am in the process of making a distribution box containing (1) 50amp 3phase plug (for shop power), (1) nema 14-50r for home power, and (2) sets of 30amp receptacles(gfci for the neighbors essential circuits). Essentially it is a 803 for 90% of us but the third 50amp leg will definitely be useful. The second gain is that parts are a little bit easier to come by than the 803/802. It has the same engine used in jeeps (for export only) a few years back, some construction equipment, and the Isuzu "pup" pickup so most engine parts are available from jeep and elsewhere. For me it is also a little easier to work on especially the batteries and air filter (both have their own doors) and the other access doors are positioned a little higher as well. It does have an oil sampler valve that i cant figure out why it's needed.

I bought my MEP-804a mostly for the three phase power. I have a large air compressor that runs with either a 15hp or 20 hp engine. I may get a 15 hp electric motor to power it, I have not quite made up my mind yet. I also have large woodworking equipment on three phase. So far, my phase converter has been OK but I have a Torrit cyclone chip collector with a 7.5 hp motor that makes my MEP-003a grunt!

Robert

I found the pdf for the gen set at http://www.liberatedmanuals.com

This is a very common problem on the MEP-804A. Its probably the hand pump "O" rings, or the check valve in the handpump.

The reason you can not find the manual fuel pump is because you are not looking at the right books. There are books for the gen set, and books for the Engine. The engine books show the pump, how to use it and how the thing can be taken apart and put back together again. And then comes the engine parts manual. Books that pertain to the gen set are:
TM 9-6115-643-10
TM 9-6115-643-12LO
TM 9-6115-643-24
TM 9-6115-643-24P
The engine books are:
TM 9-2815-254-24
TM 9-2815-254-24P
All the manuals you need are posted in the manuals section of SS. Listed under, "All the manuals you need to work on the MEP-804A"

m-35tom said:

the problem i see is that these are 3 phase only right? so if you run single phase you are just going to get 120-208 volts and use only 2 of the 3 windings, so you will only get a 10 kw genset. there is just no way around this if this is a 10 wire gen head as i assume it is. so without replacing the gen head ( a viable option ) you have gained nothing over a mep-803

Click to expand...

These are 12 wire gen heads sewerzuk has a Youtube video showing how to rewire a 004a for low zig zag to get 240 out of it. The 804 should be the same. The advantage I found with the 804 over the 803 is surge capability for large compressors and such and you can load down the 3rd leg with a few space heaters to prevent wetstacking and still get 52amps at 120/208 out of the other two legs. At 120v*52A=6240 for each leg so plus leg2 6240+6240= 12,480 watts to read 100% on the gauge. You can load 125-133% I think for 1 hour. The only other way around wetstacking and getting all your power out of the unit when you need it on an 803 is using a xantrex freedom sequence intelligent power manager.
ex. Its a winter night only the furnace blower, a few lights, a tv and some fridges on. Your not going to be able to maintain a 30% minimum constant load with that on an 803. So you have to have some sort of 3000watt dummy load to keep up the load while your in a low power demand time of day to prevent wetstacking. But then you get up in the am and turn on the coffee pot and jump into the shower. You have an electric hot water tank and a well pump with your 3000 watt dummy load still on you might see your power limit on the 803. but with the power manager you set your dummy load as the least priority and it will shut it off if it sees your reaching your load limit that you programed into it. You can also use it on an 802 for your Central air in the summer this way it will shut down your air if the wife starts the dishwasher and the toaster oven. it will keep your air off until your below programed power consumption to turn back on. If this all sounds too complicated to you then get the 804 and just keep the 4500watt dummy load connected to the 3rd leg all the time and not have to worry about it wetstacking ever or programing in anything fancy. Just my 2 cents. The power manager is used in RV's to prevent shore power nuisance trips. It does take 120/240 but for load like the ac you just leave that connected to your breaker panel and use the DC output to trip your condenser contactor(thermostat wire going to the outside unit). Some of the better Automatic transfer switches for nat gas whole house units have this load shedding technology in them as well.
https://www.youtube.com/watch?v=YmF4Awr3uc4
https://www.youtube.com/watch?v=MUe7Wg0XDow

Unfortunately the MEP-804 has a 10 wire head not a 12.

I read another thread on here where another gentleman did the sewerzuk mod and it didnt work at all. The mod would have made a dead short to 2 legs back to the generator head because the 2 grounds are bonded in the head if i read the schematic correctly on a 10 wire (804a,b)

Perhaps Novaman, you need to start at the beginning. There are one or two differences between the MEP-004A or MEP-005A, And the MEP-804A, aside from the enclosures.

does anyone know how to convert a 804b from 3 phase to single phase? just bought genset and want to use it for home power.