MEP-003A No voltage/High Voltage

[Hertzhurt]

I know this is a fairly common question, but the title was the simplest I could boil it down to.
I have two MEP-003A generators. One that runs totally fine and produces power and another that I bought for a song that does not produce voltage unless the start circuit is engaged causing the field to be flashed. I pulled the VR out of the bad gen and put it into the one that runs fine. It produced voltage at max output implying that the VR is faulty. My question is, what else would be faulty on the bad generator to cause it not to produce any voltage at all. I'm planning on getting a new VR from GreenMountain.
I have checked the diode board and the CVT and CV which all checked out ok. The only thing I can think of is the inductor pack in the reconnect box, it's pretty rough looking.
I used to be a generator tech for Cummins, so I have a decent understanding of generators, but the way these old MEP's are set up is very clever, but they have some weird additions that modern generators don't have. Any help is appreciated.

 

[Scoobyshep]

The 002 and 003 have quite the odd regulator setup. If you need a regulator board, @kloppk might be a good person to annoy.

Things I check now from lessons learned:

Water separator direction (same for fuel filters)
Circuit breaker (had one burn a pole and not close completely)
Control circuit breaker, had a few die, The last at 3 am during a hurricane.
Injection pump, Hope you have an ambac, I keep the rebuild kit and plunger guide on hand
theres a mod for the flash diode, if it fails the flash current can reach the starter and pull it in while running and burn the starter out.
test the battery charging alternator.

 

[Scoobyshep]

If you havnt done so already, the TMs are here https://www.steelsoldiers.com/threads/all-the-tms-you-need-to-work-on-the-mep-003a.155936/#

-12 operators manual
-24p parts
-34 maintenance

 

[Hertzhurt]

The 002 and 003 have quite the odd regulator setup. If you need a regulator board, @kloppk might be a good person to annoy.

Things I check now from lessons learned:

Water separator direction (same for fuel filters)
Circuit breaker (had one burn a pole and not close completely)
Control circuit breaker, had a few die, The last at 3 am during a hurricane.
Injection pump, Hope you have an ambac, I keep the rebuild kit and plunger guide on hand
theres a mod for the flash diode, if it fails the flash current can reach the starter and pull it in while running and burn the starter out.
test the battery charging alternator.

That is some great advice. I will probably order a rebuild kit and plunger.
The "bad" generator starts up and runs great with no issues at all. It only has 156 hrs and the hour meter still works.
When i got it i flushed out the whole fuel system out and changed the fuel filters.
Thanks for the quick reply!

 

[kloppk]

The 002 and 003 have quite the odd regulator setup. If you need a regulator board, @kloppk might be a good person to annoy.

Here's a video on how the 002/003 Voltage Regulation system works. ---> 002/003 Voltage Regulation

 

[Hertzhurt]

Here's a video on how the 002/003 Voltage Regulation system works. ---> 002/003 Voltage Regulation

That is a great video if not the only video which pretty thoroughly goes through the system in detail, I stumbled across it in my search actually while trying to figuring out my problem before I decided to ask here. I know you guys get a million questions that could be answered with a few simple google searches, so I tried my hardest to go as far as I could before coming here.
I assumed Kloppk was being ironic about asking you for a VR board.
What's your opinion on Green Mountain's new boards? I fairly decent at circuit repair and was contemplating just tackling the old VR board to see what went bad.

 

[Scoobyshep]

Here's a video on how the 002/003 Voltage Regulation system works. ---> 002/003 Voltage Regulation

I was trying to find that video, I will add it to my bookmarks

Sent from my SM-S908U using Tapatalk

 

[Ray70]

For short money I would just buy one of Kloppk's updated VR's then if you want you can play around trying to fix your original.
Most likely you have 1 or more blown transistors on yours, but also sounds like your parts gen has more than just a VR problem.... but 1 step at a time!

 

[Guyfang]

Keep in mind, the V.R. is older than lots of members here. Yep, you can repair it. Instructions are in the -34 TM. Would I? No. At the end of the day, you have an old V.R. with a few new parts.

 

[Scoobyshep]

Theres a v

That is some great advice. I will probably order a rebuild kit and plunger.
The "bad" generator starts up and runs great with no issues at all. It only has 156 hrs and the hour meter still works.
When i got it i flushed out the whole fuel system out and changed the fuel filters.
Thanks for the quick reply!

Theres a very important pre step here. Make sure its an ambac pump the guide and kit is useless on a bosch pump. (not to mention the bosch pumps are not supported at all.)
So you ask How can i tell? Quite easily, actually. reach under the pump there should be a somewhat circular part of the body casting. If theres a big flathead screw its a bosch. no screw ambac.

 

[Hertzhurt]

Theres a v


Theres a very important pre step here. Make sure its an ambac pump the guide and kit is useless on a bosch pump. (not to mention the bosch pumps are not supported at all.)
So you ask How can i tell? Quite easily, actually. reach under the pump there should be a somewhat circular part of the body casting. If theres a big flathead screw its a bosch. no screw ambac.

So I looked at the pump on the "good" generator and it IS an Ambac pump! I'll have to get myself a rebuild kit. I should probably just rebuild the pump anyway. It takes a while to get started and smokes for the first probably 5-10 minutes. It's not oil though, as soon as it clears up though it runs great. I try to load bank it ramping it up to 100% every other month for at least 2 hours.

 

[Scoobyshep]

So I looked at the pump on the "good" generator and it IS an Ambac pump! I'll have to get myself a rebuild kit. I should probably just rebuild the pump anyway. It takes a while to get started and smokes like a bastard for the first probably 5-10 minutes. It's not oil though, as soon as it clears up though it runs great. I try to load bank it ramping it up to 100% every other month for at least 2 hours.

Could be timing too.

 

[Hertzhurt]

Could be timing too.

How often does the timing go out? I'll have to read up on how to even check timing on that engine. I was thinking after you mentioned the rebuild kit that the plunger could be sticking causing it to under fuel on start up.

 

[Scoobyshep]

How often does the timing go out? I'll have to read up on how to even check timing on that engine. I was thinking after you mentioned the rebuild kit that the plunger could be sticking causing it to under fuel on start up.

I had one come in with the wrong button installed, I know it was the wrong one because it was too thick. And I imagine after thousands of hours of operation they can start to wear a little bit thinner.

There's a procedure in the technical manual,

Short version is you take the spring out of the pump roll the engine over till your on the port closing mark of the compression stroke roll the engine backwards a little bit monitor the fuel coming out of the number one pump output, roll the engine slowly forward until the fuel stops if the arrow lines up with PC then you're perfectly in time. But don't take my word for it read the manual and follow it step by step.

You need the fuel pumps running. You have to power the stop solenoid, remove it or wedge it up. The IP throttle needs to be wide open.

Now for my "secret sauce". The manual tells you to roll the engine using a socket on the fan bolt. I find that using a screwdriver on the generator blower (the one between the head and engine) allows for a finer amount of control.

 

[Ray70]

Difficulty starting and smoking when the engine is cold can also be an indication of a skipped plunger guide where the plunger has skipped 90 or 180 degrees withing the plunger guide, however this pretty much always has 1 other side effect where the valve cover will get hot very quickly. After shutting off, restarting is usually also difficult if not impossible until it cools down a bit.
BUT, as Scoobyshep mentioned, it could also be a sign of an incorrect timing button.
For added info read here: https://www.steelsoldiers.com/threads/a-tale-of-two-timing-buttons.198352/

 

[Hertzhurt]

Ok, so to get slightly back on track with my original problem, I installed the new VR and diode board along with a new inductor reactor which I had found one of the coils read open (black box with 6 terminals in the back corner of the reconnect box). I fired up the generator and it started to make voltage for about a second according to the gauges but as it came up to operating RPMs they all dropped to zero, and I was right back where I started where it will only produce voltage if the start switch is engaged while running. I'm worried I blew out something on the new VR board. I was too frustrated to test anything further as it was already dark out. I'm kind of at a loss at the moment, I'll do some more troubleshooting later this week, but just figured I'd see what you guys thoughts were. I did test the old VR trying to see what had gone bad on it and Q2 (transistor) I'm fairly certain is bad. I'm leaning towards that there might be a short in the CVT but i'll need to pull that out to bench test it because I don't have a megger where the generator is.

 

[Ray70]

It was only making voltage because you were holding S1 and flashing the field, as soon as you let off S1 the VR i supposed to take over but apparently it isn't.
To check the CVT you don't need anything more than a DMM, just disconnect the small wires and test the windings according to the TM instructions, you'll know right away if one has a problem!
Pulling out the CVT is not something you will look forward to doing, so test it in place.

 

[Hertzhurt]

Here is some more backstory that i didn't think was relevant, but thinking about it, i might as well share it. When I got the generator it had a problem with starting and upon initial investigation i found that one of the wires to S1 was disconnected and the negative lead going to the control box from the starter was on the wrong terminal. So someone was in it at some point screwing around where they shouldn't have been and i'm worried I going to have to wire trace and verify each terminal. I'm fairly certain that I blew out Q2 on the new VR. I have to verify that, but i'm pretty confident.
What would cause Q2 to overvolt?

 

[Ray70]

I couldn't tell you exactly what would have blown out Q2, but I can tell you that you can replace it pretty easily. I used to buy them pretty cheap on ebay etc. to keep on hand. Starting problems alone can blow the transistors, but I assume the starting issues have been corrected now?
The theory is ( although some will dispute it ) that idling the machine or otherwise running far below 1800 rpm will overload the transistors.
I have seen more that a couple that had starting and / or running issues, usually related to the IP or injectors and had blown VR transistors as well.... are they related?? I think so.
It sounds like the first order of business is to spend a bit of time verifying your wiring.
Since you have a good running machine the easiest thing to do normally would be to swap entire assemblies to narrow down the issue, like swap the entire AC reconnect box to see if the problem lies there or swap the Control Panel to check everything there, then once the bad assembly is determined, then dig down to the component level.
However, if you have a wiring issue you don't want to risk blowing up the Good assembly by hooking it to other mis wired components. So investigate your wiring first.

 

[Scoobyshep]

I couldn't tell you exactly what would have blown out Q2, but I can tell you that you can replace it pretty easily. I used to buy them pretty cheap on ebay etc. to keep on hand. Starting problems alone can blow the transistors, but I assume the starting issues have been corrected now?
The theory is ( although some will dispute it ) that idling the machine or otherwise running far below 1800 rpm will overload the transistors.
I have seen more that a couple that had starting and / or running issues, usually related to the IP or injectors and had blown VR transistors as well.... are they related?? I think so.
It sounds like the first order of business is to spend a bit of time verifying your wiring.
Since you have a good running machine the easiest thing to do normally would be to swap entire assemblies to narrow down the issue, like swap the entire AC reconnect box to see if the problem lies there or swap the Control Panel to check everything there, then once the bad assembly is determined, then dig down to the component level.
However, if you have a wiring issue you don't want to risk blowing up the Good assembly by hooking it to other mis wired components. So investigate your wiring first.

I know the 004s and larger will suffer avr damage if idled too long. I seem to remember reading something about the way the 002 and 003 regulator system ran prevented that kind of damage. Still something I wouldn't risk.


Might want to check T1 and T2. these are feeding power to the AVR board.