MEP-002a Master switch not corresponding to position

[Spring1898]

Hello All,
Was working on another MEP-002a and just got it ready to test start and was going to prime the system.
Hooked up the batteries with the master switch in the off position, and when the battery was connected the fuel pump started running?
I double checked the position as off and out of curiosity switched it through the other modes. Preheat doesn't make any noise, but the starter position worked normally. "prime" positions don't engage the fuel pump.

I unplugged the battery and noticed the glow plug area was hot to the point you wouldn't want to leave your hand there long.
It is almost as if all the positions shifted?
I am going to leave it alone for a while and will take a peak behind the panel later on.
Any ideas what it might be?

Mechanical things I am okay with but I know next to nothing about electrical.

 

[Chainbreaker]

The first thing I would do is remove the control knob off the switch post and make sure it is intact and sets on the flat surface of the switch post properly. If the knob or post is rounded or set screw loose, perhaps it re-indexed itself so pointer is off? BTW, preheat never makes any noise.

 

[Spring1898]

Don't think that is the case since Preheat an Start positions are both correct.

On my other MEP, preheat always "clicks" when turning on. Same with the truck and the car glow plugs

Behind the panel looked good too, so looks like i may be tracing some wires

 

[Chainbreaker]

Don't think that is the case since Preheat an Start positions are both correct.

On my other MEP, preheat always "clicks" when turning on. Same with the truck and the car glow plugs

Gotcha, you mean you normally hear the initial relay click (no sound after actuation is normal) and you are not hearing that when turning to pre-heat position. However, you say preheat/start are correct but that preheat is on (hot to touch) even when not activated if I understand correctly? If so, you are right there may be some miswiring going on. Preheat relay K2 side X1 should be going to pin 15 on S1 Master switch. Take a look at the schematic on top of your control box, it is top most circuit on right hand side.

 

[Spring1898]

From what I can tell it looks like the correct wire is going to the preheat. Also, all the wiring inside the box looks the same, like the same amount of fade and same blue color.
The hour meter is newer (430~) and the battery meter doesn't move at all, and the lights for the controls don't come on (one bulb is busted)

As for the Master Switch positions:
Preheat = Does Nothing (fuel pump running)
Off = Fuel pump running
Aux Prime/Run = turns on glow plugs
Prime/Run = does nothing. No noise, nothing
Start = turns over motor

Could I have a defective master switch?

Anyway I am going to hit the hay and take a crack at it another day

 

[jamawieb]

From what I can tell it looks like the correct wire is going to the preheat. Also, all the wiring inside the box looks the same, like the same amount of fade and same blue color.
The hour meter is newer (430~) and the battery meter doesn't move at all, and the lights for the controls don't come on (one bulb is busted)

As for the Master Switch positions:
Preheat = Does Nothing (fuel pump running)
Off = Fuel pump running
Aux Prime/Run = turns on glow plugs
Prime/Run = does nothing. No noise, nothing
Start = turns over motor

Could I have a defective master switch?

Anyway I am going to hit the hay and take a crack at it another day

On the schematics it will show which pins are activated at each position (preheat,prime/run,start, etc). First make sure all the wires are hooked up properly and then you can turn the knob in each position, testing for 24volts in each pin that should be hot. I would beat that the switch has failed.

 

[mtn man]

I think you nailed it- bad switch

 

[Spring1898]

Anybody know a place for a switch?

What goes bad in these switches? All I can think of is that part of the rotary mechanism must have gotten seized activating different parts of the circuit at the wrong position?

 

[kloppk]

There is one available on the big auction site. $90

 

[doghead]

I got mine from Delk's.

 

[Spring1898]

That's what it appears to be. Pulled apart the switch and looks like something arc'ed inside there, spotwelding some of the connections. Part of the assembly is cracked also.

By the way, I have another unit where the master switch feels stiff. Any way to lubricate it?

 

[Spring1898]

Okay another question.
Started working on the other 2 generators. One seems to work fine. so 1 for three now.

The other has an ASK and looks fine, but it just "sounds" a little different. For some reason I feel that it is only running on one cylinder. Will they run up to speed on only one cylinder?
Small but noticeable struggle when connecting a 1500w load, which the good gen set tackles without any noticeable change.

 

[jamawieb]

Okay another question.
Started working on the other 2 generators. One seems to work fine. so 1 for three now.

The other has an ASK and looks fine, but it just "sounds" a little different. For some reason I feel that it is only running on one cylinder. Will they run up to speed on only one cylinder?
Small but noticeable struggle when connecting a 1500w load, which the good gen set tackles without any noticeable change.

More than likely the injectors. If you notice it struggling a little with 1500w, put some more load on it and see if it can handle it. If the hertz's drop more than 3hertz with 100+ percent load on the meter, I get the injectors popped tested by Storeman. Fixing the injectors usually solves the problem.

 

[Spring1898]

Okay, I may try a VW trick first with lubro moly, and see if I can't fix it through chemistry. If that doesn't work then I can assume more of a mechanical issue.
Old Diesel did smell pretty stale in the lines.

 

[Light in the Dark]

There is one available on the big auction site. $90

I contacted this seller before, on that unit.. and made them an offer of $75. They came back with a counter of $80. I declined (didn't actually need it)... but its a real good price for a NOS unit.

 

[Light in the Dark]

That's what it appears to be. Pulled apart the switch and looks like something arc'ed inside there, spotwelding some of the connections. Part of the assembly is cracked also.

By the way, I have another unit where the master switch feels stiff. Any way to lubricate it?

I believe you can use contact cleaner.

 

[Spring1898]

What do I search for it under?

 

[Guyfang]

How about NSN? or MEP-002A?

 

[Spring1898]

Got it,
Just sent them an offer


What about those little metal clips that hold the filters in the fuel canisters?
Any substitute for those or do I just need to buy a set?
Are they even necessary if you align the filters correctly?

Was thinking of just bypassing one of the canisters temporarily to see if the genset will run. My diesel fuel is of good quality so not concerned about contaminates.