Mep 831 no power at load legs troubleshooting help

[mullamr]

Picked up two Mep 831's during the last Lockborne auction. Both with 2 hours since last reset in 2012. Conducted all the PMCS prior to attempting to start. The first started, load tested and runs flawlessly. The second started, smoked a wee bit more than the other, produces power to the convenience outlet and frequency converter output but will not produce power to the load legs.

Referred to the TM for trouble shooting the following symptons:

1.) The no fuel warning light remains on even after filling the tank and resetting the fault reset.
2.) The circuit interrupt does not seem to close and does not light
3.) The emergency stop and power switch do not shut the engine down and requires the engine to be shut down manually

My thought process was to start with the most logical and simplest method and test the fuel level switch. The TM indicates to place the positive probe of a multi-meter to the P4-10 and the neg to test point 31. Cant seem to find the the location of P4-10 test point

So my questions are:
Where is the P4-10 test point?
Will replacing the fuel level switch correct the other symptoms?
Am I starting the trouble shooting sequence correctly?
Should I be looking at something else?

Any advice will be appreciated.

 

[Guyfang]

Picked up two Mep 831's during the last Lockborne auction. Both with 2 hours since last reset in 2012. Conducted all the PMCS prior to attempting to start. The first started, load tested and runs flawlessly. The second started, smoked a wee bit more than the other, produces power to the convenience outlet and frequency converter output but will not produce power to the load legs.

Referred to the TM for trouble shooting the following symptons:

1.) The no fuel warning light remains on even after filling the tank and resetting the fault reset.
2.) The circuit interrupt does not seem to close and does not light
3.) The emergency stop and power switch do not shut the engine down and requires the engine to be shut down manually

My thought process was to start with the most logical and simplest method and test the fuel level switch. The TM indicates to place the positive probe of a multi-meter to the P4-10 and the neg to test point 31. Cant seem to find the the location of P4-10 test point

So my questions are:
Where is the P4-10 test point? The P4 is a canon plug. Look into the gen set. Find the A2, (fault indicator) and remove the plug. When you are looking for it in the schematic, it is the J4/P4. P means plug. J means jack, or female side.

Will replacing the fuel level switch correct the other symptoms?
Am I starting the trouble shooting sequence correctly?
Should I be looking at something else?

Any advice will be appreciated.

.

 

[DieselAddict]

I was going to post a screen grab of the connection in the TM but when I open it its so bad I can't read it. Totally unusable.

I need to find a more legible copy so I can put it on the list to restore.

 

[DieselAddict]

Found one!

 

[mullamr]

Ok- referred to the laminated schematic found inside the genny and found the J4 plug There was reference to the P4-10 port and it said it was located in spot 26 of the female J4 connector. Completed the trouble shooting sequence and did not have any of the required 20-32 volts when the unit was placed on the "on" position. So I believe the fuel level switch is bad. Will replacing this correct the other problems? or is this just the first part of several other issues ? I suppose I could swap the the part from the running genny if needed. Is the fuel level switch readily available?

Any and all advice will be appreciated

 

[DieselAddict]

We don't know for sure yet how many issues you have. We have to solve them as they come.

Nothing will work with the low fuel alarm active. To test you can jumper across the switch at the tank to simulate a closed switch. See if that gets you control power (24v DC) to run the unit. If jumping the switch doesn't get the light to go out you'll need to check the wiring.

 

[Guyfang]

Ok- referred to the laminated schematic found inside the genny and found the J4 plug There was reference to the P4-10 port and it said it was located in spot 26 of the female J4 connector. Completed the trouble shooting sequence and did not have any of the required 20-32 volts when the unit was placed on the "on" position. So I believe the fuel level switch is bad. (Try pulling the switch, and looking at it. I may be stuck. It may be broken. There may be dirt or crud on the tube. In any case, test it IAW the procedure in the TM.) Will replacing this correct the other problems? (You do not even know if its bad yet. Slow down and take one step at a time) or is this just the first part of several other issues ? I suppose I could swap the the part from the running genny (this is a viable troubleshooting trick of last resort. First follow Diesel Addicts advice of jumping the plug) if needed. Is the fuel level switch readily available? (Do not start throwing parts at the machine. Troubleshoot, then get whats needed, if at all.)

Any and all advice will be appreciated

.

 

[mullamr]

Ok- I unplugged the two red leads from the harness to the switch and jumped them as recommended. I left the other 3 wire connector (black, blue & yellow) connected- No fix same issues. Then decided to run with the red wires unplugged and wallah everything worked as it should. She's producing power, shuts down and all gauges work.

Worked the wires a bit looking for loose connections and reattached everything and all malfunctions and no fuel fault indicator still appears.

Checked two red leads coming from fuel switch and they have continuity - so i'm beginning to think there may be a wire issue somewhere between the connector and the plug???

 

[Guyfang]

Pull the switch, and test IAW the procedure in the book.

 

[Guyfang]

To test, Check continuity between J11 pins 1 and 2. Move the lowest float up and down, to see if the thing works. When the float is all the way up, you should have continuity. When its all the way down, no continuity.View attachment Dok1.docx

 

[gstirling]

Dieseladdict - thanks for the schematic, but can't quite make out, is that "K6" or "K8" on the short circuit relay contacts between P17 and J17. as i have been curious what the machine actually senses when the overload short circuit lite comes on. if my machine has sat for a bit and humidity has been hi, or its rained (i keep it covered so no water enters the machine), it will bring in the "overload short circuit" once or twice on start - till it warms up?? then clears and seems to run fine. had attributed this to the machines moisture sensitivity i keep reading about on the various threads.

 

[mullamr]

Ok pulled the switch and yes the bottom float was lightly gunked up and stuck to the bottom of the tube. I did find that when the floats (both J-11 & J-8 are at the lowest position on the tube there was continuity between them and when they were at their highest there was no continuity. A light cleaning and and the switch now works as it should and the generator functions as it should. All other symptoms have corrected there self. I even surprised myself and did lose any of the washers while removing both the fuel switch and sending unit during the process.

I want to say thanks to Guyfang and Dieseladdict for there help and all their knowledge and posts relating to the 831

 

[Guyfang]

Dieseladdict - thanks for the schematic, but can't quite make out, is that "K6" or "K8" on the short circuit relay contacts between P17 and J17. as i have been curious what the machine actually senses when the overload short circuit lite comes on. if my machine has sat for a bit and humidity has been hi, or its rained (i keep it covered so no water enters the machine), it will bring in the "overload short circuit" once or twice on start - till it warms up?? then clears and seems to run fine. had attributed this to the machines moisture sensitivity i keep reading about on the various threads.

gstirling, please start your own thread for your problem. It is tough for us to keep your problem separate from the person who started this thread. It will help both of you, as you will get folks focused on your problem, and not the problem someone else has.


That would be K8.

 

[Guyfang]

To test, Check continuity between J11 pins 1 and 2. Move the lowest float up and down, to see if the thing works. When the float is all the way up, you should have continuity. When its all the way down, no continuity.View attachment 724017

I made a mistake here. I wrote it backwards. My Bo Bo. Sorry.

 

[gstirling]

thanks - was really just wanting the K8, i should have left the rest off.