MEP-831A engine repair

[loosegravel]

 

[Ray70]

Wow, what a deal! Essentially you paid for the injector and got 30 additional OEM parts for free! Can't beat that price!

 

[loosegravel]

Wow, what a deal! Essentially you paid for the injector and got 30 additional OEM parts for free! Can't beat that price!

I know! I tried to Google that kit number, but nothing comes up. I actually ordered a new connecting rod and the “valve cap” from someone else because I didn’t know that they’d be in this kit. I’ll just return them.

 

[loosegravel]

Well, I had a productive and successful day with that Yanmar L70 engine. I got that bad boy back together and running on the bench. I’ve got a 12vdc fuel pump that I use around the shop to transfer fuel etc. I supplied fresh fuel to the IP and used a couple of spare 12vdc batteries wired in series while using my remote starter button. I cranked the engine around with the starter while holding the compression release until I could see fuel at the fitting on the injector. Then, I tightened the fitting at the injector, cranked it over again and it lit right off. I’m done for the day, but tomorrow I’ll get the engine installed back into the unit and see if it will make power

 

[loosegravel]

One thing that I forgot to include in that last post. This engine kit came with (2) of the “valve caps” that I was inquiring about earlier in this thread. The parts diagram and the service diagram both only show (1) of them on the exhaust valve. I went ahead and installed the on top of both of the valves and adjusted them accordingly. It seems to work just fine and the best part is the compression release works like it should now

 

[loosegravel]

Ok, the engine is back inside of this unit. I have it running and just going through the governor system set procedures. I have checked the linkage spherical nut and it’s showing one thread at the bottom. Step 2 of the actuator GAC is confusing to me. “Make sure the actuator lever reaches the end of it’s stop just prior to the engine fuel lever reaches its stop.” It doesn’t say what the position of the manual start knob should be. It definitely makes a difference.

Step 1 of the speed/load controller GAC says to adjust the speed pot on the governor control to obtain a PMA voltage of approximately 178 +/- 2vac. I’m not sure what PMA is or where to measure it. I have not messed with any of the pots on the governor control. I want to make sure that I know what I’m doing before making those adjustments.

There’s also some instructions over on the right side with some photos. The governor springs are in the correct position. The no-load adjustment for the manual start in the photo above the springs also refers to PMA voltage. Since I don’t know where to measure the PMA voltage, I’ll leave that one alone too. Would this setting be the first step in all of the above? Thanks as always for the help! Jeff

 

[fb40dash5]

Step 1 of the speed/load controller GAC says to adjust the speed pot on the governor control to obtain a PMA voltage of approximately 178 +/- 2vac. I’m not sure what PMA is or where to measure it.

The PMA is the Permanent Magnet Alternator (AKA the thing attached to the engine). You want to measure voltage between terminals A&B on the controller. The hand knob is setting the RPM "floor", so you want to move it towards 'start' to raise the no-load RPM, or toward 'stop' to lower RPM. The upper screw with locknut sets the highest you can lock the hand knob at, farther in = lower manx RPM floor.

I haven't had the joy of trying to make one of the GAC controllers work, but I can say I'm very happy mine had one of Kurt's controllers in it already. Just set that and the magnet gap, and with his you're good to go...

 

[kloppk]

The two circled terminals are where you measure the PMA voltage.

 

[loosegravel]

The PMA is the Permanent Magnet Alternator (AKA the thing attached to the engine). You want to measure voltage between terminals A&B on the controller. The hand knob is setting the RPM "floor", so you want to move it towards 'start' to raise the no-load RPM, or toward 'stop' to lower RPM. The upper screw with locknut sets the highest you can lock the hand knob at, farther in = lower manx RPM floor.

I haven't had the joy of trying to make one of the GAC controllers work, but I can say I'm very happy mine had one of Kurt's controllers in it already. Just set that and the magnet gap, and with his you're good to go...

Very cool. Thanks for the help. Now that I know where to measure the PMA voltage I should be able to proceed here. I still don’t know if Im supposed to set the no load on the manual start knob fist though. I’ll try that. Thanks again!

 

[loosegravel]

The two circled terminals are where you measure the PMA voltage.
View attachment 890903

Thanks Kurt!

 

[loosegravel]

Cool! I’ve learned a lot about these MEP-831A 3kw units. It’s all adjusted and making good power. I was able to load it down and it performed great! Someone mentioned in another thread that they use a couple of small lawn mower batteries in their unit. I went ahead and purchased a couple of these and wired then in series. Seems to work just fine. My charging voltage is right at 27vdc. I’m blowing some smoke out the stack, even with a load. Maybe this is “a characteristic of the beast” being an air cooled engine. Or maybe it’s residual soot left behind in the muffler. At any rate, thanks all for the help and the response on this thread!

 

[loosegravel]

 

[Guyfang]

Let it run an hour or three under load. Then see what the exhaust looks like.

 

[loosegravel]

Great idea. Thanks.

 

[loosegravel]

Interesting. Out of the blue I now have a high engine temp fault. This engine has only two switches on it. The one closest to the oil filter is the low oil pressure switch. (I disconnected it with S1 in the run position and the low oil fault did not illuminate) So the one on the rear of the engine must be the high engine temperature switch. I also disconnected this switch and the high temp fault doesn’t clear. Of course I’m assuming that it’s a NO switch and it closes when it gets hot enough.

Unlike the other 8XX series generators, this unit has no schematics on the enclosure anywhere. I can’t seem to locate them in the TM’s either. I did find the test procedure for the fault indicator module in the TM’s however. With 24vdc applied to terminal 7(+) and terminal 6(-) and then a jumper between terminals 7 & 8, the high temperature fault latches. It resets with the push button like it’s supposed to. All of the fault indicators seem to be operational on the fault indicator.

So I just need to find out what the wire numbers are on the two pin connector at the switch and find out where they go from there. It appears that I’m getting a false 24vdc signal on pin 8 on the fault indicator module which is latching this fault.

I would be happy to start yet another thread for this new problem if needed. Thanks!

 

[fb40dash5]

Wiring diagrams are at the veerrrrrrry end of the TM... which I learned while trying to thumb through it on my phone one evening in the cold.

 

[loosegravel]

Wiring diagrams are at the veerrrrrrry end of the TM... which I learned while trying to thumb through it on my phone one evening in the cold.

Excellent! Thanks my friend!

 

[kloppk]

Correct. The HT switch in the back of the block is a NO switch.

 

[loosegravel]

Correct. The HT switch in the back of the block is a NO switch.

Ok, thanks Kurt. I’m going to see if I can find the schematics it the back of the TM like fb4 said. I’m sure that it’s a simple problem.

 

[loosegravel]

I'll stop short of commenting on the wiring schematics in TM 9-6115-639-13&P. I finally found them way in the back on pages 581-591. (Thanks to fb4) I'll just say that I'm used to the awesome schematics in the other 8XX series and leave it at that! But, I think that I found what I'm looking for. Something is supplying + voltage to pin 8 on P4 which is the 10 pin connector on the back of the A2 fault indicator. This is what's turning on the high temp fault, even with the HT switch disconnected. It's interesting that this fault doesn't shut down the engine. It actually prevents it from shutting down. At least that's what I'm dealing with here anyway. Tomorrow's another day!