Mep-003a

[rbeeson]

I am new to the military generators; I recently purchased a mep-003a it's a 1986 model it runs great pulls good power, but when it warms up its act like its stubbles some only when warm. When it does it you can see the governor arm move not sure if the governor is causing the issue or if its fuel related. I have had the injectors rebuilt and replaced two of them main fuel pumps. Doesn't seem to be as noticeable when loaded but still stubbles. When it does it the lights will dim in the house. Has anyone ever had this issue on the mep-003a. Thanks for any help given.

 

[Scoobyshep]

Welcome to the club.

This is the kind of thing where a video would be helpful. The down side is the forum doesn't have the ability to post them directly, but you can upload them to a file share site or youtube and link them here.

On an unrelated note there's a starter wiring mod you should check for in the control cube, see attached

 

[rbeeson]

Welcome to the club.

This is the kind of thing where a video would be helpful. The down side is the forum doesn't have the ability to post them directly, but you can upload them to a file share site or youtube and link them here.

On an unrelated note there's a starter wiring mod you should check for in the control cube, see attached

Thanks for the information on the starter deal, I'll check it out. I'll try and upload a clip of it running and try to link it.

 

[Chainbreaker]

Starting with some BASICS:

1. Just out of curiosity, what is your outdoor ambient temperature recently when running genset? If it's still warm out, make sure the Air Cleaner Cannister is set to summer. I doubt being set wrong would cause the engine to stumble but it's good to check that the Air Cleaner slider adjuster is set correctly for appropriate running conditions. Usually, I only set it to winter when ambient air temp is in the 30's or below.

2. Also, how many hours on the Hobbs meter & have all the fuel filters been changed out?

3. Where is the star adjuster set on the Governor Arm yoke? If I recall correctly, it should be close to the middle of the worm gear (I think 4th notch down). If set incorrectly it can cause potential hunting (RPM's varying) that could cause engine RPMs to hunt/stumble under load somewhat.

4. Also, if by chance you have some heavy electrical loads (AC, Electric Dryer, etc.) come on suddenly along with other house circuits pulling average loads it could cause an intermittent stumble as engine tries to compensate for a sudden "heavy AC load dump" if engine, fuel, air systems have any issues.

 

[rbeeson]

Starting with some BASICS:

1. Just out of curiosity, what is your outdoor ambient temperature recently when running genset? If it's still warm out, make sure the Air Cleaner Cannister is set to summer. I doubt being set wrong would cause the engine to stumble but it's good to check that the Air Cleaner slider adjuster is set correctly for appropriate running conditions. Usually, I only set it to winter when ambient air temp is in the 30's or below.

2. Also, how many hours on the Hobbs meter & have all the fuel filters been changed out?

3. Where is the star adjuster set on the Governor Arm yoke? If I recall correctly, it should be close to the middle of the worm gear (I think 4th notch down). If set incorrectly it can cause potential hunting (RPM's varying) that could cause engine RPMs to hunt/stumble under load somewhat.

4. Also, if by chance you have some heavy electrical loads (AC, Electric Dryer, etc.) come on suddenly along with other house circuits pulling average loads it could cause an intermittent stumble as engine tries to compensate for a sudden "heavy AC load dump" if engine, fuel, air systems have any issues.

Doesn't seem to matter what the outside temperature is, she runs smooth till it gets some heat built up. Has 59 hours on the meter, all fuel filters and complete engine service just done will all filters changed. I believe the governor is set about midways down I'll have to recheck it. This thing reminds me of an engine skip when it happens, no smoking when it does it. I don't know if it just needs to be run appears it has set and not a lot of run time.

 

[Tinstar]

Don't forget to add two-cycle oil or some other fuel additive to your diesel for lubricity.
Will keep the injection pump/injectors happy since the older equipment isn't designed for todays ultra low Sulphur diesel.
Add a can of Seafoam to your fuel to keep the fuel system clean.

I'm not much help on your issue since I have very limited experience and knowledge on military generators.
But I do learn something new here everyday........

 

[Tinstar]

rbeeson please include your state in your profile.
It's required.

 

[Ray70]

Typically the governor needs to be on the 4th turn up from the bottom ( 3 exposed "coils" showing below the spring ) if you are more than 5 up from the bottom the governor is probably not adjusted right.
A simple test is to get it hot, load it up and when it bogs down, try lifting up slightly on the throttle linkage at the injection pump.
If you are able to manually increase engine speed that way, that rules out things like fuel and air issues and points towards the governor being incorrectly adjusted.
If you can not increase engine speed, since you aren't seeing smoke at all, I would think it's a fuel delivery problem.

 

[Ray70]

I assume this machine had sat a long time when you received it, if so did you have any other difficulty getting it running at first?
Reason I ask is that there is a very common issue on these engines with the Injection pump plunger getting stuck when the fuel gets old and varnished. If you crank the motor over with it stuck the plunger guide is designed to split in half, like a shear pin, to protect the pump.
Often times the plunger guide doesn't split fully, it just spreads apart a bitt the plunger skips 90 and then breaks free and starts working, but now the injection timing in 90 or 180 degrees off.
This usually results in hard starting, but once running it will run fine for a little while.
The valve cover will begin to feel abnormally hot within about 5 minutes and within 10 minutes or so it will start running poorly and probably stall eventually and won't want to restart until it cools off a little.
If yours starts fine and the valve cover is not getting uncomfortably warm to touch within 5 mins. then this is probably not your problem.

 

[rbeeson]

It has always started right up since I

Typically the governor needs to be on the 4th turn up from the bottom ( 3 exposed "coils" showing below the spring ) if you are more than 5 up from the bottom the governor is probably not adjusted right.
A simple test is to get it hot, load it up and when it bogs down, try lifting up slightly on the throttle linkage at the injection pump.
If you are able to manually increase engine speed that way, that rules out things like fuel and air issues and points towards the governor being incorrectly adjusted.
If you can not increase engine speed, since you aren't seeing smoke at all, I would think it's a fuel delivery problem.

I'll give that a check and report back. Thank you sir
have had it.

 

[rbeeson]

I assume this machine had sat a long time when you received it, if so did you have any other difficulty getting it running at first?
Reason I ask is that there is a very common issue on these engines with the Injection pump plunger getting stuck when the fuel gets old and varnished. If you crank the motor over with it stuck the plunger guide is designed to split in half, like a shear pin, to protect the pump.
Often times the plunger guide doesn't split fully, it just spreads apart a bitt the plunger skips 90 and then breaks free and starts working, but now the injection timing in 90 or 180 degrees off.
This usually results in hard starting, but once running it will run fine for a little while.
The valve cover will begin to feel abnormally hot within about 5 minutes and within 10 minutes or so it will start running poorly and probably stall eventually and won't want to restart until it cools off a little.
If yours starts fine and the valve cover is not getting uncomfortably warm to touch within 5 mins. then this is probably not your problem.

I'll give a check as well. Just got to pull the sounds encloser off to check.

 

[Ray70]

That's the 1 down side to having the ASK, makes things a pain to work on! If your governor spring doesn't look like it's in the right place, look at the governor droop procedure in the TM, it will explain the procedure to get it set correctly.

 

[Scoobyshep]

This one's a little harder to test but I have had those springs fatigue before and apply less tension than needed causing erratic operation

Sent from my SM-S908U using Tapatalk

 

[rbeeson]

That's the 1 down side to having the ASK, makes things a pain to work on! If your governor spring doesn't look like it's in the right place, look at the governor droop procedure in the TM, it will explain the procedure to get it set correctly.

Will do.

 

[rbeeson]

This one's a little harder to test but I have had those springs fatigue before and apply less tension than needed causing erratic operation

Sent from my SM-S908U using Tapatalk

Thanks for the information.

 

[rbeeson]

Okay so I know its been a while since i have posted new information about my running issue. I had shoulder surgery and was unable to work on it. So, I check with my TM book and made sure governor seems to be set right which I believe it to be. Crazy thing is it runs fine till warm then governor arms starts pulling up on fuel pump arm. This is not consistent, and it just does it intermittingly for no rim or reason will do it loaded and unloaded. This thing starts right up cold and pulls good power no smoking just trying to get this fixed. All the governor rods appear straight and in good working order. The adjuster is about midways down. You think the valves could be out of adjustment or something going on with governor assembly on the front of the engine.?

 

[Ray70]

Can you post a picture of where your governor spring is on the adjusted?
1/2 way down sounds way too high, as mentioned up above you typically need to be no higher than the 4th groove up from the bottom.
If memory serves me right, that is more like 1/3 the way up from the bottom, not 1/2 way.
1 Pic. will = 1000+ words!
Additional pictures of the governor linkage may also reveal something of importance.

 

[Ray70]

Did you try manually pushing up on the throttle linkage as mentioned in post #8?
The result of that test might help point us towards a fuel delivery issue or a governor issue.

 

[Ray70]

If you have a valve that is adjusted too tight you could have compression when cold, then loose compression in that cylinder when it heats up and the pushrod expands, so definitely something worth checking, and it's easy to do!

 

[2Pbfeet]

Would an air leak that opens up when warm cause that behavior?

All the best, 2PbFeet