MEP-831a help cranks won't start.

[Heavymetal1985]

I have just started dealing with the MEP-831 units and so far I have had good luck with the ones I have bought but, I have one that I just can't figure out. The unit in question cranks over and puffs smoke but will not start and run. The following is a list of things I have done to the unit so far but with no luck. I have gone through the trouble shooting guide and everything checks out but I went ahead and replaced the following items one at a time from a good running unit governor control, governor actuator, relay, diode, injector all with no luck. I have figured out that the heater (H1) is defective but since it is not cold I would think it should start anyway. Any help would be greatly appreciated.

Heavymetal1985

 

[DieselAddict]

How much compression do you have?

If you disconnect the fuel line from the injector and crank it over do you get a good squirt of fuel?

 

[Dwnorton1]

That would been my next question, compression. If you have fuel and air, only thing left. These units will run without any control's as long as magnet releases. Low compression will definitely prevent you from starting.

 

[Heavymetal1985]

Yes I get a good squirt of fuel but, I have not compared it to a running unit which I will do.

 

[Heavymetal1985]

That has been my thoughts! Heck it's a diesel, I have fuel, air and yes compression. Like I said I will compare the fuel flow to a running unit that I have and will follow up. One other thing is there a good way to bring the 24v battery back from who knows how long of not being charged or should I just replace it? I have been dealing in the 802 & 803's for a while along with the plasma freezers and just started messing with the 831's. I deal with a large group of full time RVers and some have been wanting these 3k units but man are they touchy.

 

[AfghanVeteran2010]

Have you looked at fuel water separator, Does it have water in it? Whats the hour meter indicate? Do you have compression? Is the decompression lever engaged?

Edit: Also the valve lashing is that in spec.?

 

[Heavymetal1985]

All new along with fuel lines. I replaced it thinking I might be sucking air from somewhere.

 

[Heavymetal1985]

206 hours on the unit and compression lever works as intended.

 

[Guyfang]

Look into the control panel. Locate relays K12, K14 and K15. insure they are properly seated. Notice that two of them are RELAYS. One of them is a SWITCH. They look the same. But are not. If all three are the same, (look at the part numbers to tell) then you need to get the one you are missing. K12 and K14 are the same relay, ( NSN: 5945-01-461-2084, Part number: RH2B-ULDC24 ). K15, ( NSN: 5945-01-260-3792) is the SWITCH. The part number should look something like this. RH2B-ULC-AC-120. There are about 4 different part numbers, but important is the AC-120, 120AC, AC-120V, or something like it. Best is if it has the NSN.

Now, go to page, (PDF reader page 126), and read the test procedure for testing K12. If K12 is good, and you have the right elays, in the right position, go to the step below.

Press and hold the fault reset switch. HOLD IT IN THE RESET position!! Then try and start the set normally. What happens? Does it start, or not?

 

[Dwnorton1]

Guyfang is right on in the K15 is 120vac coil and the rest are 24vdc. I've had 3 of these and 2 had the with the relays swapped. If I were having this issue, I would likely just lift the linkage from the electronic governor to the so the the only electronics that the unit requires to be in use are the fans to the inverter (critical ask me how I know) and fuel pump and starter. These little Yanmars are some tough little dudes. You very well could be on to something with air being sucked in giving you problem.

 

[Heavymetal1985]

Thanks. All the relays and K15 switch are correct. I have extra of the relays. I will try holding the fault reset in and see if the unit starts once the monsoon stops. After humping in the rain for 24 years I try and stay out of it now a days.