MEP 531A Fix-up Thread

[WWRD99]

I wanted to revive this old thread in case anyone is still watching.

I kept some of the parts when I parted this out. One of the was the potentiometer for the voltage adjustment. I grabbed it from my parts bin to use on something & went to use it with no luck. Tested it, and it was dead! Basically no reading (open) across almost the whole range.

So, I am thinking.... could the issue with this generator have been this the whole time? If the POT was bad, it would have made the voltage adjustment call way off, and made the regulator put out bad AC voltage as well.

I just HAD to come back when all this came racing back into my head. Kinda disappointed if this is the case, but, someone else can hopefully learn from my mistake hopefully.

I just got 2 more of these generators & they are in great shape with really low hours. They don't need anything except fuel lines, filter, & fuel! So, I'll be learning about them again.

I didn't know you did a short video of flashing the genset! Just came up after the new video. Now I need that diode and I'm going to check that voltage adjuster...might get power out of it!

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[synelecpb]

Dang I may have to check that on mine since it just spins easily without stopping!! I still need that diode lol....haven't touched that set in a long time!! Might have to give a little more testing on it!! I have been watching a ton of these on sale in New Jersey next week so I may end up with another too.

I bought one. Pickup scheduled for next Thursday. It appears to be missing the fuel lines and bowl. Will update with photos after I get it from Southampton. Fingers crossed its a good one!!

 

[WWRD99]

I bought one. Pickup scheduled for next Thursday. It appears to be missing the fuel lines and bowl. Will update with photos after I get it from Southampton. Fingers crossed its a good one!!

Ahhh...I watched those!! Had a ton of them.

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[2Pbfeet]

Thanks for posting the video.

Personally, I prefer to finish bleeding all the air at the injector, but that's just me. In my experience, those engines are very sensitive to any residual air in the high pressure line, and don't have much power or stability until the air clears the high pressure injection line.

All the best,

2Pbfeet

 

[FarmingSmallKubota]

I bought one. Pickup scheduled for next Thursday. It appears to be missing the fuel lines and bowl. Will update with photos after I get it from Southampton. Fingers crossed its a good one!!

Good luck when i was buying them out of PA they never tested them and got 4 bad ones out of 9 , I have 7 coming from michigan at least i know they turn over and i have parts machines

 

[Guyfang]

Thanks for posting the video.

Personally, I prefer to finish bleeding all the air at the injector, but that's just me. In my experience, those engines are very sensitive to any residual air in the high pressure line, and don't have much power or stability until the air clears the high pressure injection line.

All the best,

2Pbfeet

The MEP-531A is a strange beast. Due to the location of the clear fuel line from the Fuel Bowl and the IP, often there is a bubble trapped, and bleeding at the Injector will not get it out. The CECOM solution was to use a wire tie, to pull the fuel line down a TAD, and the air bubble comes right out.

 

[WWRD99]

Good luck when i was buying them out of PA they never tested them and got 4 bad ones out of 9 , I have 7 coming from michigan at least i know they turn over and i have parts machines

Got mine in pa...got it running but still no power output...it sits now.

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[Icesythe7]

There was like 100 of these things for sell recently on GP figured I'd pick one up myself in a few weeks after everyone else gets theirs so hopefully price drops a bit.

 

[CallMeColt]

The MEP-531A is a strange beast. Due to the location of the clear fuel line from the Fuel Bowl and the IP, often there is a bubble trapped, and bleeding at the Injector will not get it out. The CECOM solution was to use a wire tie, to pull the fuel line down a TAD, and the air bubble comes right out.

It's an odd, angry, and loud fella.

I didn't know that was there solution, I came up with that on my own. Guess it's just common sense.

 

[FarmingSmallKubota]

It's an odd, angry, and loud fella.

I didn't know that was there solution, I came up with that on my own. Guess it's just common sense.

The thing that has puzzled me is that I have one unit, as well as a Yanmar 5500 watt generator and the injector pump intake nozzle faces the other way therefore eliminating the 90 degree fitting and the curve that causes the air bubble not sure why they would not have made that change at some point in production.

 

[CallMeColt]

The thing that has puzzled me is that I have one unit, as well as a Yanmar 5500 watt generator and the injector pump intake nozzle faces the other way therefore eliminating the 90 degree fitting and the curve that causes the air bubble not sure why they would not have made that change at some point in production.

Someone put a different injection pump into the one that is different. Yanmar has different part numbers for the different injections pumps, depending on what side the fuel comes in.

 

[GASCANS001]

Howdy all,

Been a while since I started one of these!

View attachment 864993 View attachment 864994

Got myself a MEP 531A at auction. Definitely had a bunch of hands in it, but, I got one of the best deals that was had in a while on one.

I knew right away the breaker was pushed into the panel and the cover over the gauges was missing.

Replaced some fuel lines, a few fuel tank fittings, hose clamps, and put in some missing bolts at the alternator that held it to the bracket. Checked to be sure the governor fork was correctly on the injection pump via the inspection window. Added some 15W-40 Rotella T4 and diesel. Took the slave cable out of my M1078 & cranked for about 20 seconds, got nothing. Found the clamp at the injection pump loose. Tightened and it fired right up!

Gave it a little while to finish purging the air while I put away the cable.

Nothing at the gauges. Breaker was tripped. Found a broken wire at the breaker. Made a quick jumper to test. Still nothing. Fuse at panel okay. Fuse holder okay.

After some reading, decided the flash the alternator. Boy, the TM is not great at explaining this! Took me like 4 hours to figure out where this needs to be done. I made a video on it;

After flashing for about 15 seconds, breaker stopped tripping. Nothing on the gauges though.

I'm getting ~ 15 volts AC at 8 & 9 on TB-1. There is nothing covering this in the TM. Flashed a couple more times with no different results. Tried searching and nothing came up for results. Any ideas group?

Watched a lot of your videos my friend!
Just picked up a 531a wasn’t making any power either. No gauges were working terminals dead the whole nine.


I flashed it and got all the gauges back. Everything is showing spec but no juice. Breaker still tripping instantly. Fuses good even switched them around.

now the nitty Gritty, I tested 8&13 and got 125v tested 13&15 and got 140v

following the instructions. My voltage is low on the 13&15 but I don’t know where to go next. I know the manual says to go to g2-f1 or something like that and I’m very confused. This is the worst TM to follow I think I’ve ever seen!
Your kind insight would be greatly appreciated

 

[CallMeColt]

Watched a lot of your videos my friend!
Just picked up a 531a wasn’t making any power either. No gauges were working terminals dead the whole nine.


I flashed it and got all the gauges back. Everything is showing spec but no juice. Breaker still tripping instantly. Fuses good even switched them around.

now the nitty Gritty, I tested 8&13 and got 125v tested 13&15 and got 140v

following the instructions. My voltage is low on the 13&15 but I don’t know where to go next. I know the manual says to go to g2-f1 or something like that and I’m very confused. This is the worst TM to follow I think I’ve ever seen!
Your kind insight would be greatly appreciated

I'm honestly not that great with these. I've either just ended up not figuring them out or they're good. Maybe someone else will chime in with more help. I'm sorry!