MEP-831A Governor Control Replaced - no start

[DieselAddict]

Reuse is ok

 

[zapp]

Well.. got the fuel IP back installed and bled the system. It fired right up! . Of course, it can't be that simple.. At first I got an Overload/Short fault light come on and the engine turned off. I restarted and got a low oil sensor light and it turned off. I changed the oil, checked the filter, and it's the same thing. Low oil fault and engine off. Looking through the TM it just says if the engine has less than 15 PSI it will fault. Is there a way to test the oil pressure switch or something else I should be looking at?

Engine run and low oil fault:

 

[kloppk]

The OP switch's fail fairly often in the 831's.
Hopefully you actually do have oil pressure!

You can disconnect one of the wires to the switch to prevent it from reporting/falsely reporting that fault.
** If there is a real OP issue it won't shut down!

 

[zapp]

Yep, two wires on OP switch. I took 1 of 2 wires off and started engine. No low OP fault but actuator arm went back to magnet and turned off. Restarted and manually moved throttle/actuator arm which then resulted in overload/short fault. Starting to think this has more problems going on. Going to try and look at the electric diagram and understand the logic of where the signal is coming from to shut down..

 

[kloppk]

Shutdown comes from the A2 Fault Monitor. When a fault is reported to it A2 turns the K12 FAULT relay on. K12 is the leftmost relay behind the gauge panel. When tripped K12 will have an LED on it in. When that happens K12 removes power from the Governor Controller module causing the engine to shut down.
The OL/SC faults are detected inside the Inverter and those faults are sent to the A2 Fault monitor.
Unfortunately, the Inverters in these sets can be fussy and throw OL/SC faults when there aren't any.

 

[2Pbfeet]

FWIW: Generally, the L70s build oil pressure rather quickly, i.e. a a second or two, and with cold oil often to pretty high pressures. (A probable cause of the oil sensor failures in these engines in my own view.)

All the best,

2Pbfeet

 

[zapp]

Thanks a lot! Appreciate the detailed info! I'm trying to break this down in to smaller bites and step through to isolate. I noticed when I took a wire off the OP switch the magnet engaged and the engine stopped but K12 didn't have an LED on indicating it had been energized or a fault sent. Can the inverter be unplugged to determine if the fault is coming from it or test points? I've been searching and saw your thread on humidity impacting the inverter board and potentially sending an OL/SC.

 

[Light in the Dark]

@kloppk are these small sets like the larger TQGs, where you have to hold S1 till sufficient pressure builds?

 

[Guyfang]

NO.

 

[kloppk]

As Guy said no. The OP usually shots up to about 125 PSI quickly after starting. Way more than the 15 PSI LOP cutoff.

 

[zapp]

Update.. I put a multimeter on the OP sensor and checked continuity per the TM and it tested ok. I started looking at the governor actuator arm and realized I hadn't tightened the nuts on the rod and it had spun up 3/4 of an inch form the bottom threads. Readjusted and locked nuts in place and fired it up. Everything started up and runs very well now. Low OP light goes off, and the OL/SC does not appear. Checked power on the courtesy outlet and got 120V, GFCI test worked, and then checked lugs L1-L2 was 240V and L1/L2 to N separately was 120V. Tested running a angle grinder and the engine ramped up and then ramped down after I turned it off..

Still have a couple issues:

1/ After I use S1 to "Stop" the generator, the actuator arm stays attached to magnet when I try to restart. If I move it manually away from the magnet it fires right back up. Is this a calibration I still need to do?

Video:

2/ If I let the generator run for 10 minutes then move S1 to "Stop" the generator gauges all seem to shutdown, however, the engine doesn't stop. I have to move to "Run" which throws fuel into the engine causing it to rev and then move to "Stop" and it turns off. What's weird is if I start the engine let it run only for a minute or two and then "Stop" it actually turns off. Seems like when it runs more than a couple minutes.

Video:

3/ Hour meter didn't seem to move. I saw in a different post the terminals should have 28VDC? This sound right?

 

[kloppk]

Typically, the failure of the arm not lifting off the magnet is due to the magnet strength being set to high. Yes, it's adjustable.
To adjust for less strength loosen the nut securing the magnet to the bracket. Screw the magnet inside the circular collar a bit deeper into the collar. Re-tighten the nut.

The failure to properly stop is usually due to the gap between the arm and the magnet is too wide at no load. Adjust to 5/16" per the TM. If it's still not stopping reliably make the gap a bit smaller.

 

[Guyfang]

The TTM, Time Totalizing Meter works on 24 VDC.