MEP-804B Problem Starting

[Rik]

I have a MEP-804B (Yanmar Engine) and I have a problem that just developed.

I was using the Generator and shut it off for a few minutes and then when I went to restart I get nothing, meaning the fuel pump does not run, the engine will not turn over and thus will not start.

History: Unit has 470 hrs on it and performs excellent. In the past when I turn the ignition switch to start it cranks over and starts or I hear a click, if I hear a click I simply turn the switch to off and repeat and for some reason the 3rd attempt (if it does this) is starts and on with life.

Trouble shooting:

I checked the batteries and they are putting out 25V
I can jump the starter and the motor spins over but does not fire up
I checked the breaker behind the panel (7.5 amp) and it has 25V in and out
I checked the power to the ignition switch and it has 25V on terminal #8
I checked the voltage at the starter and it has 25V
I went to the dead crank switch and it is in the run position but it will not crank over the motor when I flipped the switch to the crank position
I made sure that the emergency shut off was in the run position

So:

I thought it was the ignition switch so I purchased on from 'Green Mountain" and I just changed it and to my surprise the problem still exist.

What could cause the engine to not start, crank, turn on the fuel pump, open the fuel cutoff ??? Is there a breaker somewhere that I do not know of?

Thanks in advance.

 

[Guyfang]

Panel lights come on?

 

[Rik]

Panel lights come on?

No...

 

[Guyfang]

This should be an easy thing to solve. Look at this schematic. Trace the wires from the BT-1 and BT-2. Thats the batteries. The 24 VDC comes from the BT-1 and BT-2, to the MT4. Check at MT4 at pins 1&4. You should have 24 VDC. The 24 VDC then goes from MT4-1 to S10-2 Mesure at S10-2. What do you have? Then at S10-3. What do you have.

 

[Rik]

Thank you!

Where is the MT4 located on the generator?

Currently my batteries go to a plug that accepts an outside power cord with the + on one side of the plug and the - on the other side of the plug.

From there (memory) the positive goes to the starter and then smaller wires go to?

 

[Guyfang]

I take it, you do not know how to read a wire diagram or TM's.

 

[Rik]

I take it, you do not know how to read a wire diagram or TM's.

WIthin reason. The manuals do not show where things are located only a simple diagram for most of the items.

I downloaded the TM on the generator and it uses a block flow chart to explain things but makes no references as to their actual size/location so some things become an adventure to find.

I can trace this out but it's easier when I have a general idea as to the are as the area behind the control panel is not labeled MT4 and such. But I will search. My generator is 90 miles from my home location so it's a drive to find something if I have to trouble shoot multiple things and get feedback each time.

Any idea as to the problem?

Thank you!

 

[Guyfang]

WIthin reason. The manuals do not show where things are located (Thats what the -24P parts TM is for) only a simple diagram for most of the items.

I downloaded the TM on the generator and it uses a block flow chart to explain things but makes no references as to their actual size/location (All electric parts are labeled next to the item.) so some things become an adventure to find.

I can trace this out but it's easier when I have a general idea as to the are as the area behind the control panel is not labeled MT4 (Is located behind the control panel) and such. But I will search. My generator is 90 miles from my home location so it's a drive to find something if I have to trouble shoot multiple things and get feedback each time.

Any idea as to the problem? It sound to me like the S10 is in the wrong position or that S17 is non op, or that the canon plug going to the control cube is loose or has fallen off. You are getting no power to the control cube. The lights should work, at least. The first place to check is MT4, The batteries are charged? They read at least 24 volts?

Thank you!

 

[Rik]

Yes, firs thing I did was suspect the batteries and I put the Fluke Meter on them and they make 25V at various points on the geneartor. Panel switch included. AMP Meter and other locations

I didn't download the -24P parts TM as I didn't know it existed but was starting to think I need to search for an electrical diagram

Thank you

 

[Guyfang]

All the TM's you need are here.

All the TM' you need for the MEP-804B

This should be all the TM's you need to work on the MEP-804B gen set. Basically, its the same books as the MEP-804A, with the addition of TM 9-2815-538-24&P, the new engine book.

www.steelsoldiers.com

 

[Guyfang]

Yes, firs thing I did was suspect the batteries and I put the Fluke Meter on them and they make 25V at various points on the geneartor. Panel switch included. (What panel switch. Thats one reason I always refer to the switch name. no confusion then) AMP Meter (What amp meter? I assume the DC meter, M4) and other locations

I didn't download the -24P parts TM as I didn't know it existed but was starting to think I need to search for an electrical diagram

Thank you

 

[Rik]

Yes, firs thing I did was suspect the batteries and I put the Fluke Meter on them and they make 25V at various points on the geneartor. Panel switch included. (What panel switch. Thats one reason I always refer to the switch name. no confusion then) AMP Meter (What amp meter? I assume the DC meter, M4) and other locations

I didn't download the -24P parts TM as I didn't know it existed but was starting to think I need to search for an electrical diagram

Thank you

Sorry, the ignition switch. It has 25V on the #8Lug. Voltage drops when I turn the ignition switch to start and then leg 3 has like a 6V power running through it and I believe lug7 does as well.

Yes the "Battery Charge Ammeter" has the 25V on it's legs.

What I didn't check was the voltage to the "Dead Crank Switch" as getting to the backside of it is not an easy task.

 

[Rik]

About to drive the 2 hrs to the generator and after reading your comments, I have concluded (maybe incorrectly) that the MT4 is the "Battery Charging ammeter Shunt" and that the S10 is the "Dead Crank Switch" . I plan on checking the current and possibly making a jumper wire if the switch is bad to test it.

I looked over the manuals and I cannot find a page with the wiring diagram that you posted and printing off what you posted is very small and distorted when printed. Any source for a better diagram?

Thanks!

 

[Rik]

Yes, firs thing I did was suspect the batteries and I put the Fluke Meter on them and they make 25V at various points on the geneartor. Panel switch included. (What panel switch. Thats one reason I always refer to the switch name. no confusion then) AMP Meter (What amp meter? I assume the DC meter, M4) and other locations

I didn't download the -24P parts TM as I didn't know it existed but was starting to think I need to search for an electrical diagram

Thank you

I cannot find the MT4. I see that it comes off the alternator and I see nothing like this in the engine compartment and nothing labeled inside the control panel box

I see a solenoid next to the dead crank switch and some type of white plastic thingy inside the voltage panel

I checked the voltage at the alternator and it has 25V on the main terminal

The dead crank when set to normal has 25v on #1 and #2 and 0 on 3

With the switch in off only #2 has 25v and with the switch turned to crank #2&3 have 5.7V

Panel light switch has 25v but when switched to on it drops to 0.8V on both wires

The battery charger CB and the DC Control Power CB both have 25V across both lugs

The cannon plugs are tight

Confused

 

[Rik]

I cannot find the MT4. I see that it comes off the alternator and I see nothing like this in the engine compartment and nothing labeled inside the control panel box

I see a solenoid next to the dead crank switch and some type of white plastic thingy inside the voltage panel

I checked the voltage at the alternator and it has 25V on the main terminal

The dead crank when set to normal has 25v on #1 and #2 and 0 on 3

With the switch in off only #2 has 25v and with the switch turned to crank #2&3 have 5.7V

Panel light switch has 25v but when switched to on it drops to 0.8V on both wires

The battery charger CB and the DC Control Power CB both have 25V across both lugs

The cannon plugs are tight

Confused

More photos

 

[peapvp]

Dead Crank S10 pinout as follows:
#2 Com always 24V when battery connected
#1 crank
#3 normal
when you have 24V on #1 crank K2 should close (24V on K2 X1) that’s on the starter
check voltage on starter solenoid K2 and L4
give starter a couple whacks with the hammer

 

[Rik]

Also the emergency shut off switch has 25v across both lugs

 

[Rik]

Dead Crank S10 pinout as follows:
#2 Com always 24V when battery connected
#1 crank
#3 normal
when you have 24V on #1 crank K2 should close (24V on K2 X1) that’s on the starter
check voltage on starter solenoid K2 and L4
give starter a couple whacks with the hammer

starter has 25v and I can jump the starter and the engine cranks fine but no fire

 

[peapvp]

Also the emergency shut off switch has 25v across both lugs

Your problem is your starter / starter relay K2

 

[peapvp]