My MEP-803a experience

[csheath]

I accidentally started it without pre-heat at 27 degrees F, sputtered a bit, but fired off.

Could probably buy a universal starter push button and wire the preheat into that.

 

[Guyfang]

A simple spring loaded single pull, single throw switch would work also.

 

[lonesouth]

Switch was delivered yesterday. Planning to put the trailer back in the yard under a tarp and move the generator into the garage to get it fixed up.

 

[lonesouth]

got the switch wired in. I'm getting an immediate low oil fault during cranking, then it goes dead. I checked the oil, it is not low oil. It was doing this before the switch broke, though it broke before I could confirm it was not user error, i.e. releasing from start too soon.

Battle short does not work. Holding in the test/reset fault switch will allow the generator to start and run, but it dies immediately when the reset switch is released.

Thoughts?

 

[Guyfang]

It will probably continue to run, if you snap the battle short up, before releasing the test/reset button. Try that. Also try an get a reading of just how much oil pressure you do have. You can of course jump the LOP. But it might be telling you the truth. So Check oil pressure before running the set for more then extremely short time periods. The only safety switched I have real respect for, are LOP and coolest high temp.

 

[lonesouth]

Flipping battle short after running did work. Oil pressure was around 50. The LOP fault stayed lit.

I found that the battle short lights works by testing(pushing in), but it does not illuminate when the switch is up. So, that's another thing to look into.

No change after the following:
Swapped S14 between generators
Disconnected oil pressure switch
Swapped K19 & K20
Swapped K12 & K20

Removing K20 allowed the generator to start

20VDC from a(DC Voltage across LOP switch normally closed) to D(ground) on Diag Port with the LOP Switch disconnected and K20 removed
pins a & b have 20VDC relative to D on Diag port with S1 in Run AND when the engine is running.

K20 should be excited in normal operation, per my other functioning genset.

 

[Guyfang]

Jump the LOP. But I think you will find that it's bad.

The reason the set ran after removing K20 is because K2 is part of the LOP circuit. The two LOP wires go to J7/P7, (pins 4&5) and from there to K20, pin 8 and K16, pin 8.

 

[lonesouth]

Confirmed P8 K20 continuous to P8 K16 with the LOP switch connected, open when disconnected. I confirmed that the LOP switch is working per TM, i.e. closed when not running, open when running. Also, no change in starting behavior with the switch connected or not.

The fault comes on after a single revolution of the engine, not after then engine is running.

 

[lonesouth]

Additional info for those curious:

Normal Operation:

S1 in either Run position, not running = K16(Crank Disconnect) closed
S1 in Start(beginning) = K15(Field Flash) closed, K16 closed, K20(Low Oil Pressure) closed
S1 in Start(after running at speed) = K15 closed, K20 closed
S1 in either Run position, after starting = K20 closed

 

[lonesouth]

What I have is K16 closes when S1 moved to Run, K20 closes immediately after S1 is moved to Start, engine turns, then a split second later, K20 & K16 open, K12(Engine Fault Relay) closes, and the engine shuts down with LOP Fault Indicator lit. All other relays behave as expected.

 

[csheath]

Does it have 24+ volts at starter to ground?

 

[lonesouth]

Does it have 24+ volts at starter to ground?

starter engages as it should.

 

[Guyfang]

And if you disconnect the LOP. it runs? No idiot lights?

 

[lonesouth]

https://www.youtube.com/watch?v=dxDCoLTonQg

https://www.youtube.com/watch?v=Ow716a_DNdI

 

[lonesouth]

And if you disconnect the LOP. it runs? No idiot lights?

If i disconnect the LOP switch, same behavior. Assuming I'm disconnecting the correct thing. Unhooking the two red connectors in the below pic.

The only thing I've found that will let it run, is either holding the test/rest on the fault panel, or pulling the LOP relay.

 

[Guyfang]

And you have connected it right? Wire 143C goes to pin C and wire 126A goes to NC?

 

[csheath]

starter engages as it should.

I was just wondering if low voltage was causing a problem. Shouldn't it have 24 at the LOP?

 

[Guyfang]

Yes, it should. What do you have?

 

[Guyfang]

One last thing before I go to bed. Unplug the A2, Fault Indicator, and try an start it up. If it runs, change the A2 and see if that fixes it. Have seen this problem before.

 

[lonesouth]

Yes, it should. What do you have?

S1 in run, negative probe on rivet at dead crank switch
143C = 11.76
126A = 20.67

those should both be 0 or close to it <1V?