MEP804B - no start

[MstrFiksIt]

MstrFiksIt to Guyfang

I looked all through the forum and while performing some test you had layed out for someone I manged to take a good
running generator and made it so it will not start. My meter lead slipped and something made a quick pop like a fuse and now all the diagnostic lights are on but it wont crank and I can seem to find the culprit. all the fuses I can find are good all the circuit breakers I can find are not tripped. please help i dont see what I am missing.

Guyfang
What were you checking, when you made it spark. Also, did you reset the fault indicators?

MstrFiksIt
es I reset them. The lights all stayed on for a while but since my last message to you the lights went off and the gauges quit working. I was testing for 24v signal at the low voltage module K5 I believe. I am currently not by the machine but can be again tomorrow afternoon or Monday. The lights on the diagnosis panel are all off now when you crank it with the dead crank switch it cranks but using the start switch it just clicks like a relay is bad. But not sure where to check next.bmy original problem was it ran fine but when you turned on the voltage interrupter it would not stay on. If you held the switch up voltage was present at the lugs.

Thanks for any help you can give.

Guyfang
Put the S1 start switch in the run position. Measure with your multimeter, from ground to plans 2,4,6 and 8 on the S1. You should have 24 volts. What kind of S1 do you have? If you don't know, or haven't read a thread about the difference between them, take a picture of the back side of the switch. Look in the control panel and make sure the circuit breaker is pushed in. Make sure the S17 emergency switch is pulled out. Let's stop here, as it doesn't pay to give you too many things to do. You can also do the troubleshooting, if you can follow it. As I am 6-7 hours time deference then you, I may not always be on line at your time. It's 00:15 right now.

I will check them tomorrow and let you know what I find. I appreciate your help. I am new to the site. If I can figure out how to start a new thread I will do so. Then others can benefit from your knowledge too.

Using a multimeter I have battery voltage at 2,4,6 and 8 on the S1. s17 is pulled out. if anyone else has Ideas feel free to join in. I orignally posted this as a private message because I was not sure where and how to post but i wanted to make sure we shared our conversation so that others could benifit from the knowledge that Guyfang was sharing with me.

 

[MstrFiksIt]

Here is the S1 Picture

 

[MstrFiksIt]

I dont see MEP804B manuals. can anyone tell me which ones to use for diagnostic testing? when I crank using the start run switch the solenoid on the engine opposite the starter clicks but no power to starter solenoid exciter. if I go to the starter an bypass everything it cranks but still not able to start. boy I hope I didnt ruin something expensive.

 

[kloppk]

Manuals... https://greenmountaingenerators.com/manuals-and-support/mep-804a-mep804b-mep814a-mep814b-manuals/

Here is the list of manuals Guyfang put together for the 804B

MEP-804B	15 KW		LO 9-6115-643-12
MEP-804B	15 KW		TB 9-6115-643-13
MEP-804B	15 KW	4TNV84T-DFM	TM 9-2815-538-24&P
MEP-804B	15 KW		TM 9-6115-643-10
MEP-804B	15 KW		TM 9-6115-643-24
MEP-804B	15 KW		TM 9-6115-643-24P

 

[MstrFiksIt]

I found two transistors blown on the diagnosis board. Found new part online. Stuck now until I get new part. Then we can proceed to why the AC switch won't stay on.

 

[Guyfang]

The book for the -B model is in the SS manual forum. Look closer. There is only one book, as the only difference between The A and -B is the engine.

by diagnosis board, do you mean the fault indicator? If so, the set will run without it.

 

[Guyfang]

In TM 9-6115-643-24 is the troubleshooting steps for no start, (will not crank). It will be on page 83 of your PDF reader, or page 2-21 of the manual. I cant think of a better place to start.

 

[MstrFiksIt]

Okay great! I will run it tomorrow. Thank you!

 

[MstrFiksIt]

Update to situation

Okay, so after many attempts at finding the problem, I asked for more of the story. the alternator was replaced recently and this generator came from an auction, so not much in the way of history. I am not sure why but the shield wire at the alternator was connected to the positive post instead of the ground. I repaired the wiring and I installed the new diagnostic board that I found burnt and now I am on to diagnosing the power output of the AC generator.

1. engine starts
2. with battle switch on I can turn on the ac power. from neutral to L1 L2 and L3 I have 118.5 volts
3. under voltage light is on
4. engine quits, even with battle switch on after running for about 30 seconds or so.
5. turn everything off then back on and starts over.

not sure where to look from here. can anyone tell me where to go next and what to look for. I think the under voltage relay might be bad because I dont see an under voltage problem. the output voltage on the gauge however is only getting to 200 volts despite what I measure at the lugs with the interrupter on.

I hope this is enough info to move on to the next step please advise.

thanks
Gary

 

[MstrFiksIt]

Based on the test for the under voltage light being on i have determined that the under/over voltage relay #60177 is bad. the under voltage normally open circuit is always closed. when performing the test to make it over voltage as in the manual the engine does not shut down right away and the over volt light does not come on. it will shut down after 30 seconds to a minute every time i start it with the under voltage light coming on every time. Does anyone know a good source for parts?

 

[Guyfang]

If you think the undervoltage relay is bad, jump it.

By diagnostic board, I assume you mean the A2, Fault indicator?

Start the set. As soon as it runs, press the A2 reset button and hold it it. Flip S7 up into the on position. Let the reset go. Will it keep running?

 

[MstrFiksIt]

No it will not keep running.

 

[MstrFiksIt]

not sure how to jump it

 

[Guyfang]

You can still jump the relay. Simply disconnect one side of the normally open circuit. Since you remove one side of the circuit, its now permanently open.

Look up the part, in the parts manual. Put the NSN, or the part number into your browser. It should come up.

Do you know what a UOC (Usable On Code) is?

 

[MstrFiksIt]

I do not know what a usable on code is. when i disconnect the one wire of the normally open is still dies after 30 seconds. I think I have more than one issue. i just noticed on the fault board that over volt looks like an act of shut down but not under volt. am I interpreting that correctly?

 

[Guyfang]

The UOC is a code in your parts manual. It tells you what part goes to what model gen set. Look at the cover of your manual. It lists the MEP-804a, MEP-804B and the MEP-814A. You have a MEP-804B, (I think you said) and the difference between the A & B gen set is the engine. But what is a MEP-814A? If you look in your manuals, you will find that the 814A is a 400 hertz machine. So it is logical to assume that there are different parts for the same function. I will use volt regulators as an example. Can you use the same volt regulator for a 60 hertz machine as for a 400 hertz machine? Probably not. So you need to look up the part in the TM and see if there is only one part number for the relay. You also need to look up what UOC code is for the 814A and 804A and 804B. So why dont you try that. I will be up a little longer but not much. Its 23:16 hours here.

 

[MstrFiksIt]

Mine is a MEP804B 50/60hs NSN6115-01-530-1458

FSCM 60177 part number 19210

 

[Guyfang]

Very good. I lied to you about the possibility of there being two different relays, (in this instance anyway) but wanted you to KNOW that there is the possibility. For instance, look at item 31 of the same page. Transducer, motional. Two different numbers. The UOC is the only way to tell the difference between them.

I am almost sure I saw a Under/Over voltage relay for sale in that big auction site. Look it up, and see.

 

[MstrFiksIt]

I will thank you and goodnight for now.
any thoughts on the auto shut down? it would appear that the auto shut down is only for over voltage not under voltage? but not sure I am interpreting the fualt indicator correctly.

 

[Guyfang]

Get into the -10 manual. On page 1-4, or page 22 of your PDF reader, in paragraph 1-7.1, it tells you what faults will shut down the engine. Overvoltage is one of them.

Page 2-6, or page 42 of your PDF reader describes the Fault indicators functions.

You should take the time to read the -10 TM from front to rear. Lots of good info in there.

Now, it's off to a wonderful Motorcycle rally for the next two days!! Take care all and have a wonderful weekend!!