MEP 003 Died

[Sarge29]

I was running my generator for an old timers reunion for my old NG unit when it just shut down. I restarted it and as soon as I released the start switch after holding it long enough for the oil pressure to build up it shuts down every time. I checked the oil pressure switch and it is good. A little history-- I was using a slave cable to start the gen. I did not have batteries in it but I did wrap the pos battery lead to prevent problems. Well as it turns out I wrapped the neg lead. (I know, should have put batteries in). After the first start the amp gauge was showing the system was running at full charge. Now it shows nothing even with good batteries. Where do I go from here?

 

[Isaac-1]

The first place I would look is the DC charging system.

Ike

 

[Sarge29]

I did check the fuse for the DC charging system and it was good.

 

[glcaines]

Look in the TM. There are very good troubleshooting guides.

 

[Sarge29]

OK, After digging into the TM's I have found that the DC stator is bad. I won't know about the DC regulator until I can get a stator and get it in. What else may have went out because I ran the gen without batteries? I didn't know that running with an open circuit (no batteries) would burn out the stator. Anyone have a DC stator they would be willing to part with?
Thanks in advance.

 

[rosco]

You might have fried one of the over-rides. Like the low oil circuit, or the over-heat, if it has one. How do you know its the stator?

 

[Sarge29]

I tested the output voltage on the stator. I got about 4 volts instead of 35 volts shown in the TM. I did not check the over-heat circuit (did not think about it) but the oil pressure circuit tested good.

 

[Sarge29]

Does anyone have a DC stator for the MEP-003A generator that they will sell? Also I need an over-heat sensor for the engine. Any help will be appreciated.
Thanks,
Sarge29

 

[Speddmon]

Sarge,

The DC side has nothing to do with your not starting issue. I notice that you said you needed a high temp sensor as well, that is more than likely your starting issue problem.

I know hindsight is 20/20, but you should have just left the slave cables hooked up to the generator and the vehicle you slaved from and let the charging system do it's thing. The worst the positive lead being loose would have caused would be a blown fuse.

As for the DC stator, if you can find someone with a 400 Hz unit they are parting they might part with theirs. The DC stuff is the same between the sets. Try calling Delk's Army Navy in NC and see if he has any. Other than that, unless you want to keep it OEM, I would just get a small 10 amp charger and plug it into the convenience outlet, mount it and wire it to the batteries. That way, whenever you start the set, the batteries will also charge.

 

[Sarge29]

Thanks for the info. You are right about the slave cables, I thought the system would work like the old car/tractor system where it would run and be ok without batteries. I guess that is what I get for thinking. I tested the high temp safety and I know that it is bad. Also tried to run the gen with the high temp sensor jumped out and it would shut down as soon as the start switch is released. As long as I hold the switch in the start position it will run and produce power. Looks like I have some more digging to do.

 

[Speddmon]

First off, don't hold that start switch too long, or you will do damage to the AC voltage regulator and/or the bridge rectifier board. I recommend 10 seconds maximum.

If it still will not run, the only other things keeping it from staying running are the oil pressure switch, and the start relay itself. The fuel solenoid is working properly from the sound of your description, since it's powered right from the start switch when starting and then drops out along with the start relay if the safeties open to shut it down.

Try jumping out the oil pressure switch and see if that fixes the problem. If not, then the start relay needs looked into.

 

[Sarge29]

Thanks, I hold the start switch a few seconds after the unit starts to be sure the oil pressure is up then I release it. I tested the oil pressure switch as shown in the TM and it is good. I have the ASK off and while it is off plan to relocate the oil press gauge so it will be visible with the kit on. I guess I will try jumping out the oil and temp switches one more time just to be sure they are eliminated then go to the start relay.

 

[Sarge29]

Update, I have the oil pressure switch and the high temp switch bypassed. I have replaced the start relay and tested the main switch as shown in the TM. Everything is good there. New stator on the DC charging system and it is working right. The DC circuit breaker tested good. This thing still shuts down as soon as the start switch is released. I am not getting any power to the fuel solenoid while the switch is in the run position. What point does the power for this circuit come from? As I understand it the only things on the unit that will drop the fuel solenoid are the high temp and oil pressure switches. Where do I need to go next?
Thanks for all of your help up to this point.
Sarge29

 

[derf]

I'd have to look at a schematic to be sure but isn't there a relay on the board that might be causing this?

 

[Sarge29]

OK, I found the culprit!! The wire going to the high temp switch was broken inside the insulation about 1 inch from the plug on the harness side. Nothing visible to let me know the wire was broken. I just started going through all of the wires testing continuity while pulling and twisting everything. Now I am off to get a couple hundred tie straps to bundle all of the wires like they were then I will put my newly insulated ASK back on. I stripped out the fiberglass and put in new armaflex foam.
Thanks for all of the help.
Sarge29

 

[Speddmon]

Glad you got it running. That was going to be my next suggestion because I had a set that had the exact same problem. One of the high temp switch wires rubbed through on the mounting frame of the air cleaner housing, where the harness bends around to bundle with the rest of the wires.