MEP-903 Generator In S-805 Electronic Repair Shelter - Road To Startup

Overdrive

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Wentzville, Missouri
Just brought home an S-805 shelter with ALL the MEP-903 generator components in tact. I wanted to use this post to document the checkout and startup (attempt) of the generator since there is very little info/discussion on the MEP-903 generators.

drive home 1.jpg

Generator Setup in The Shelter:
Generator, power input panel, inverter, power distribution panel, and the holly grail gen control panel. Also included were various power cables for shore power.

Shelter Power:
The shelter power input panel can receive power from 4 sources: Generator, 3 phase 208v, single phase 240v, and 24v through the inverter.

I put a 220v dryer/RV 50A plug (4 wire) on the end of the pigtail from the single phase 240V shore power cable that came with the shelter (2 hots, neutral, and ground). Funny how a "50 amp" RV plug is really a 220v plug with two hot 115v legs. Shelter uses the power the same as an RV, nothing is 220v. It just feeds two different 110V circuits. Even the ECU is single phase 110v.

Initially thought I messed up big time when i tried to close circuit breaker for lights. Tripped breaker in workshop and smoked a little from shelter breaker... Turns out the little indicator light for the "lights" circuit burned out and shorted. They have no fuse so it was tripping breaker. Bypassed little light and everything fired right up.

The Plan:
I am going to take my time before trying to fire up the gen as i have no idea of its current status. The hour meter on the remote control panel says 38 hours but that could mean nothing if it was swapped out. On initial inspection of the generator; the oil is full but black, not burnt; the oil filter is painted over with original gen paint (maybe 38 hours is accurate?); nothing looks out of place. The gen was designed to use remote batteries and fuel from a HMWV but I have it on a trailer so will need to get a couple of batteries and i may have a fuel feeder for a 5 gallon Jerry can from the BII on a gen trailer I have.

Steps to Start?:
1. Check/Change oil, oil filter, air filter, fuel filter.
2. Fuel hoses that went to HMWV are in tact and present but quick disconnects look old so probably change out fuel lines.
3. Two 12v batteries in series for 24v startup - maybe just WalMart Group 24?.
a. Don't think the two little batteries on my MEP-802A would start it but... ?
4. ?

I will pull the gen out of the tunnel and take more pics later this week.

Interior_001.jpg

Figured some folks might be interest in seeing this thing. How it is setup and how it works... If I can get this one going.

OD
 
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Guyfang

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Burgkunstadt, Germany
Howdy,

The MEP-903 is mysteroius because only _______________ had them, and they are all very _____________ about them. :-D
I had to go fix one once. The army people there did not want, or let me look at anything, other then the gen set. A soldier went in to try start it, but that was the problem. It would not start. And they would not let me check things at the start switch. So I drove 660 Klicks round trip for nothing, cause I went home. Stupid. Oh well, I got paid.
 

Overdrive

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Location
Wentzville, Missouri
Pics... Um.... It looks like this thing has been sitting for a LONG TIME... 36 hours on the control panel may be accurate?

gen10.jpg gen3.jpggen12.jpg gen5.jpg

gen6.jpg Fuel filter looks scary
 
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Overdrive

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Location
Wentzville, Missouri
Cleaning would seem like a good place to start. Thinking careful compressed air and sponge bath with simple green rather than a garden hose wash?

Easy to get all of the gen since it’s on a rack 2’ in the air.

Ordered fuel, oil, and air filters but fuel hoses are long and rotted so figured I shouldn’t attempt to push fuel thru them.

Gen has what the manual calls a Day tank under radiator for immediate fuel. Holds a few ounces (not much more) and acts like an 802/803 aux fuel pump when low, pumps from hummer tank.
 

Chrispyny

New member
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NY
Pretty cool. The fuel capacity being less than a gallon, i imagine this thing was made to run for short periods of time, only when required, and to pump out gobs of power when required for short periods of time.
 

Guyfang

Well-known member
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Location
Burgkunstadt, Germany
No, it's ment to run long time periods. The "day tank" is ment just to keep the fuel system from running dry. It was always ment to feed off the vehicle fuel tank. Some of these set were installed in remote equipment, ment to be left someplace and run for long time periods unattended.
 

Dwnorton1

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Healdton Oklahoma/ SOOK
I won the same shelter with different outfit inside. Mine was a comms unit. Had all the equipment that came with your except for the control panel. A guy on fleabay has control panels, but I am NOT paying the $1000-1300 he keeps bouncing back in forth on. I have a DSE controller going to use instead, just haven't taken time to do it. Good luck with yours.
 

Overdrive

Active member
411
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Location
Wentzville, Missouri
UPDATE:

Finally was able to get the gen up and running. Unfortunately, as surplus projects go, I had a few issues and a few still to fix.

Cleaned up the get set, changed the oil and filter, replaced all the soft fuel lines. Checked the radiator for coolant and didn't see any so went to top it off with distilled water and it all came pouring out the front of the radiator. Someone put a forklift fork into the lower corner of the radiator and mount which bent the mount and tore a small hole in radiator.... Sooo... off to the machine shop.

Here is the repaired radiator:
startup1.jpeg

Painted it and installed with no issues.

While cleaning off the gen i noticed the fan was hitting the radiator guard edges so when i reassembled the radiator i made sure to adjust the mounting so the fan spun clear. Filled radiator with distilled water only to flush it so i can put CAT ELC coolant in and while waiting for a new drain petcock. Stock one has some corrosion and i didn't like the way it sealed.

Found the proper wire harness for batteries to shelter and picked up a couple of group 24 batteries from WalMart. I need to get a pic of the setup for reference to add here.

Figured out a fuel setup with both a supply and return. WAY too expensive but now I have a portable Scepter fuel tank. I have the aux fuel gen cap for military generators but it doesn't have a return line port and I am missing the dip tube for 5 gallon fuel cans so i had to go with this. All marine fittings with quick disconnects.
startup3.jpeg

I didn't like the condition of the soft fuel lines so replaced them all from the tank to gen and the day tank lines.

Pic of the fittings on the day tank:
startup5.jpg

Replaced the fuel filter and bled the fuel system following the TM.

Took a deep breath and fired it up. Took 3 rounds of starter at 15 second bursts with rests in between. She did fire up and ran smooth. However, i am getting an Overspeed warning light so i didn't engage the AC circuit. Let it run for about 5 minutes to check for leaks and anything else. Ran nice and smooth with zero smoke.

No other fault lights and verified the alternator is charging DC just fine. Interestingly, with the overspeed fault it doesn't shut the gen down.

startup2.jpg
Please note how nicely the gen cleaned up from my original pics :)

Pic of the throttle actuator I HOPE is not the cause of the Overspeed problem. Will follow the troubleshooting flowchart in the TM. Check linkage, test actuator, check/test speed sensor. Fingers crossed

startup4.jpeg

Next step is to drain/fill radiator with ELC and troubleshoot the overspeed fault.

More to come!

P.S. While on battery power i did engage the shelter's inverter to see if it worked. Fan came on and it seemed to be doing OK but did not try to turn on the breakers for shelter power. Turned the inverter on an off a few times and on the third try something inside sparked. Inverter fan seemed to stay running, didn't trip the breaker, but started to smell like burning electronics so shut that sucker off and left it off. I may pull the inverter and see what's up and if it can be repaired. STUPID mistake on my part that I didn't pull the dust filter and blow out the inverter with compressed air. The inverter is not required for gen use so this problem doesn't affect generator operation.

OD
 
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Overdrive

Active member
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Location
Wentzville, Missouri
Overdue Update:
Took a break from the 805 and 903 project i was getting too frustrated but recently starting working on the 903B again. I have been using the shelter itself as a HAM radio and general hang out spot in my workshop since i brought it home.

MEP-903B Update (Over speed light):
Followed procedure in TM to check the actuator linkage. Both adjustments are correct and within tolerance. Sooo... I lubed up the linkage joints with WD40, worked them a bit and things seemed to loosen up. Also said to heck with it and backed out the governor screw on the engine. That was the ticket. Fired it up no more over speed light. Engaged the shelter power and everything powered up under gen power.

I still need to tinker with that governor screw as the gen has an electronic governor with the actuator so it should regulate itself... A bit more troubleshooting to do next. However i got the gen running and producing power. This weekend i will take pics and video of the whole setup up and running and supplying power. Also going to try to load the gen up and run it for a good few hours.

OD
 

Overdrive

Active member
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36
28
Location
Wentzville, Missouri
Guess I better put up some pics or it didn’t happen...
D1C0F411-0F37-4F5E-A81A-502AD1EB9098.jpeg
It’s kind of funny firing up the generator inside the shelter because the startup procedure using the APU has no power inside so have to use a flashlight to see the control box. Going to fix that with some DC lighting off batteries.

Pic of the shelters internal voltage meter
5EEECF99-C281-43AD-9138-A992EC9BC5F8.jpeg

And the shelter running on APU power
CC471EF0-6A10-421D-987D-957B6D4954B0.jpeg
 
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