new-to-me MEP-802a

willys2point3

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I figured I'd make a post and introduce myself since I will be heavily utilizing the knowledge base on this forum for this 1995 vintage MEP-802a I recently acquired. Lots of great information here!
The P.O. fitted the large diesel tank to the trailer. He also abandoned the factory fuel tank and aux fuel source port and has this tank connected directly to the fuel pump, for better or worse. It fires up and runs like a top, but has a few little things to address:
-a fairly significant fuel drip coming from either the return line or the injectors.
-a handful of questionable wiring repairs, mainly on engine sending units, that I intend to replace with marine grade connectors.
- it is missing about half of the screws on the outside panels, I'd like to replace all those with stainless and get all the screw holes filled.
-needs fresh fuel lines and return lines
-Some cheap parts-store 12v trailer lights were installed. I'd like to get rid of that and instead convert the original military light fixtures to 12v so I can hook it up to my truck's trailer lighting, if possible.
-determine functional state of the trailer brakes and make sure they work.
-Any other mods and preventative maintenance projects that I discover on this site :)

IMG_20210812_164654288.jpg
 

willys2point3

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Yeah I asked the guy about the weight distribution with the tank, he claimed to have never had a problem. It does have the rear support leg on the trailer though. It had about 75 gallons of diesel in it when I towed it home. The trailer seems to be almost neutral with that, balanced on the wheels. I lowered the rear support when I unhitched it but it didn't immediately fall back on the support, it is fairly balanced.
The tank will hold twice that much diesel, but I doubt I will ever need to fill it up like that. I'm leery of towing a rear-heavy trailer, I've experienced a trailer 'death wobble' before due to that, and it is not fun!
 

Godspeed131

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Here’s a link to another thread that may be your leaking fuel issue. Seems to be very common.

 

MixManSC

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Columbia SC
Another you can do is get some Chevy/GMC stock wheels for 2000-2011 models and put smaller tires on if you want to bring it down some and make it easier for towing a bit more level with civilian vehicles. I just did that on mine. Went with 30.6" high tires on stock 16" GM 8 lug steel wheels which only dropped it about 2.5" but that did make a significant difference and easier climb up on it and whatnot.

My trailer is a newer model but still very very similar. On mine the lights are different though but I did convert it to all 12v. There are a few threads around here on the wiring pinouts for that. If yours does have the original tail lights, they should just be regular bulbs in them and you just have to swap them with 12v ones so they will be bright enough.

There is also threads that list the sizes of the bolts used everywhere. Most are 10/32 and yeah, there is a TON of them and some are quite frustrating to get at. I replaced most on mine as well. I also added screens to the bottom opening and side air intakes and added a flap to cover the top opening when not in use to keep bees, etc out of it.
 

willys2point3

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Thanks! I was noticing that some folks swapped out the wheels on those trailers. My truck is a '96 Chevy K2500 that is on 33" tires and sits pretty high in the back. The trailer actually sat level behind it. I have to use a pretty big drop hitch on most trailers with that truck, this was the first trailer that worked with just the straight hitch bar :). I won't really be towing this thing around though, I'm even considering taking the gennie off and using the trailer for something else. It would make a really cool utility trailer behind my old Jeep (originally a '42 GPW, but now a "restomod" on 32" tires) if it could tow the thing.
 

steelypip

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Trailer balance: for stable towing you want 10% of trailer weight on the tongue with a single axle trailer. An MEP-802a weighs about 800 lb. The trailer's probably 500. So that's 1300 lb. Fuel's about 6 lb/gallon, so about 450 lbs of fuel in that tank. Call the whole thing 500 lbs with the tank. That gets your all-up weight around 1800 lb.

That means you need 180 lb of tongue weight for stable towing. I bet you don't have it.
 

Ray70

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I'm surprised you have any tongue weight at all with the tank full....
Normally one person can lift the tongue by hand.... barely.
Add another 500 lbs. out back and its a miracle you haven't flipped it over backwards!
 

willys2point3

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To be clear, it wasn't my idea to configure it this way. This is just how it is when I bought it and dragged it home the other day. but, as it sits it's basically neutral over the tires.

I've removed the top cover and the side cover where the fuel filters are, and discovered that whoever "plumbed" this huge fuel tank just bypassed the air/fuel filter manifold. There is no filter even there. The fuel line goes directly to the smaller canister filter. Another problem, the fuel outlet on the tank is near the bottom, and when it was plumbed they did not add a shut off valve. So there is no way to replace the fuel line going to the tank without first emptying the tank.
In the long run I may sell this big tank to a local farmer and put something smaller on there, but for now I plan to re-plumb the whole fuel system and try to figure out how to deal with the pick-up fitting on the tank without having to drain the whole thing. I have nothing that can hold 75 gallons of off-road diesel.
 

willys2point3

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NC
I got the fuel lines re-plumbed at least from the pump through the filters, got the water/fuel filter hooked back up, and fixed the leaks. It was leaking fuel from the nipples attached to the injection pumps. Both were not very tight and the copper/brass washers were boogered up a little. I still need to figure out how I want to do the fuel tank plumbing, but for now it's up and running again without leaking. I was able to re-use some of the original AN fittings and install them on new 1/4" fuel hose. The original braided hose was very brittle.
 

willys2point3

New member
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Location
NC
Today I was able to do a test run with a new transfer switch installed on our detached garage building. The 802 ran basically everything in the building, including a minisplit AC, without appearing to break a sweat. I had about 600 watts of shop lighting on, a fridge, 2 chest freezers, and the mini-split going all at once. The well pump was enabled but I don't think it kicked on. I ran it about 20 minutes like that, coolant temp held steady a little above the 180 mark.
I only noticed one significant issue, the load meter does not appear to work correctly. If I tapped on it with my finger it would bounce up to 25-30%, but then would go back to 0. I'll have to research that one on the forum here.

A few misc. things left to do to get it all sorted out:
-replace fuel return line (ordered new contitech 3.5mm hose)
-new fasteners for the sheet metal
-slight fuel leak at the banjo fitting for the secondary fuel filter
-very slight oil leak around the base of one of the injector pumps
-replumb the external fuel tank
 
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