Mep-831 wont start the next day after finally sending power

[Lettja]

Im at a loss with the tm because the troubleshooting steps are telling me to replace parts and when i do it still doesn’t work. It may be simple but i haven’t touched these since AIT and would appreciate any help.

 

[Toolslinger]

First, welcome aboard.

Never touched an 831 myself, so I can't be too much help. However, I can tell you the best thing you can do when you get frustrated with these things is to take a break, step back, and then go back to square one. Follow the TM line by line, and don't assume you did everything right. Read the step, do the step, then move to the next. It's absurdly easy to skip through, thinking you've done everything right only to find something easy. In my case I about lost my mind one day simply because I hadn't double checked the big red kill switch on my 802a.

The folks here are great, and they'll get you through this, whatever the issue is.

 

[FarmingSmallKubota]

Im at a loss with the tm because the troubleshooting steps are telling me to replace parts and when i do it still doesn’t work. It may be simple but i haven’t touched these since AIT and would appreciate any help.

First thing is to check the E-stop, lots of little things can contribute to them not starting. lets not fire the parts cannon before we truly diagnose the unit. give us some more information. One of the most frustrating things about all of these Yanmar single cylinder engines is without prime and a little air in the system they will not run or run very poorly.

 

[Lettja]

First thing is to check the E-stop, lots of little things can contribute to them not starting. lets not fire the parts cannon before we truly diagnose the unit. give us some more information. One of the most frustrating things about all of these Yanmar single cylinder engines is without prime and a little air in the system they will not run or run very poorly.

So i follow the tm troubleshooting instructions and it was fine up till the start switch and the corrective action is to pull out the estop and probe (+) on s19-a2 and (-) on tb3 test point tp31 and to flip the start switch to start and then i only get 4 volts when it says i need 20-32 vdc but i just replaced the switch with one from another genset and its still providing the same voltage. So unless both switches are broken i could only think of it being a shorted wire maybe.

 

[Ray70]

The E-stop is simply a switch so all it can do is pass through whatever voltage is going into it, so I'd start by making sure the batteries are fully charged and in good condition. If the batteries are older, make sure they have good amperage and not just a surface charge, which will drop substantially as soon as a slight load is applied.

Removed my comment about the dead crank switch, I thought you had an 813, not an 831! my mistake...

 

[kloppk]

What's the voltage across those two points with the switch in STOP?

 

[FarmingSmallKubota]

Does it start using the decompression valve and rope start?

 

[Lettja]

What's the voltage across those two points with the switch in STOP?

22 vdc in stop

 

[Lettja]

Does it start using the decompression valve and rope start?

We tried it but it didn’t work whatsoever

 

[Lettja]

The E-stop is simply a switch so all it can do is pass through whatever voltage is going into it, so I'd start by making sure the batteries are fully charged and in good condition. If the batteries are older, make sure they have good amperage and not just a surface charge, which will drop substantially as soon as a slight load is applied.

Removed my comment about the dead crank switch, I thought you had an 813, not an 831! my mistake...

Battery tester said it was fine and i get the proper voltage out of the estop point s19-a2

 

[kloppk]

22 vdc in stop

OK, that's indicating either the battery(s) are not charged/bad OR something in the path of getting battery voltage to S19A2 is failing.

Measure the DC voltage at the following points with your meters Negative lead on TP31 (chassis ground), E-STOP pulled out and S1 in START
1) Voltage at S19-A2
2) Voltage at S19-A1
3) Voltage at circuit breaker CB1. Check both terminals
4) TP30
5) Center terminal of the Slave Connector
6) Battery positive



This is the schematic path from Battery positive to S19-A2

 

[Lettja]

OK, that's indicating either the battery(s) are not charged/bad OR something in the path of getting battery voltage to S19A2 is failing.

Measure the DC voltage at the following points with your meters Negative lead on TP31 (chassis ground), E-STOP pulled out and S1 in START
1) Voltage at S19-A2
2) Voltage at S19-A1
3) Voltage at circuit breaker CB1. Check both terminals
4) TP30
5) Center terminal of the Slave Connector
6) Battery positive



This is the schematic path from Battery positive to S19-A2
View attachment 940999

Embarrassingly it was the battery and i had to be explained what a cca was. Im really just a part replacer so thanks for the help i really appreciate it.

 

[Guyfang]

I was in Vilseck on Tuesday. Had you posted this on Monday, I would have come by!

 

[Lettja]

I was in Vilseck on Tuesday. Had you posted this on Monday, I would have come by!

Well 3/4 of my 3kw gensets are down and i dont know much so if you dont mind stopping by if youre ever back in vilseck id really appreciate it

 

[Guyfang]

Where? Or if you don't want to say, I can PM you.

 

[Lettja]

Where? Or if you don't want to say, I can PM you.

Im on base at the 615th MP motorpool across from the gym

 

[Guyfang]

I pass there every time I come on post through the Netzaberg gate. Many moons ago I worked in your MP. Well, all of them on post at one time or another.