MEP-803A No crank no start

[CaryHenry]

Hello again-
Bought an MEP-803A at GP. Put new batteries in it and no crank. Glow plugs seem to work (I hear relays). It will neither crank nor run the fuel pumps and open fuel solenoid. I checked the main switch. That seems to be mostly working except term 3 doesn't have power when in start mode. I guess I need a new switch, but that doesn't seem to be the issue here.

I'm trying to follow the wiring schematic and it looks like several of these wires run through terminal block 4, but I can't find that block. I did check for power at the fuel pump and starter solenoid, and it's not getting there when I move the switch. So somewhere between the switch and the fuel pump, starter solenoid and fuel solenoid I have a break. The engine DOES crank with th dead crank switch and when jumping the starter solenoid.

Any guidance on where I should start or if there are any common issues that lead to these symptoms, I would be more than grateful.

 

[Farmitall]

Start by downloading and reading through the manuals, particularly the parts manual.

Then read them again and again and again, making note of where specific connectors and terminal strips and wiring (including the wire numbers) are physically located on the machine.

You cannot just go through things randomly and expect to successfully troubleshoot issues. You need to understand what's happening and what parts, wires, connectors make that happen.

These sets are a learning experience, but once you learn and understand how things work on them, it's very fulfilling.

 

[Light in the Dark]

I believe TB4 is on the sheet metal wall behind the S8 phase selection switch. You will need to remove the operator control cube roof to get to it.

You should buy a couple of cans of a high quality deoxidizing spray to aid you in getting this machine going. The S1 may not be bad... might be, but may also just have internal corrosion. This stuff works great: https://www.amazon.com/Hosa-D5S-6-DeoxIT-Contact-Cleaner/dp/B00006LVEU

You will want to hit every single switch, open contact, terminal board, etc (with the batteries disconnected) and articulate every knob and switch until you are bored.. then a few times more.. This will free up many issues, and get a good future corrosion inhibiting layer into the contacts.

 

[Farmitall]

I believe TB4 is on the sheet metal wall behind the S8 phase selection switch. You will need to remove the operator control cube roof to get to it.

You should buy a couple of cans of a high quality deoxidizing spray to aid you in getting this machine going. The S1 may not be bad... might be, but may also just have internal corrosion. This stuff works great: https://www.amazon.com/Hosa-D5S-6-DeoxIT-Contact-Cleaner/dp/B00006LVEU

You will want to hit every single switch, open contact, terminal board, etc (with the batteries disconnected) and articulate every knob and switch until you are bored.. then a few times more.. This will free up many issues, and get a good future corrosion inhibiting layer into the contacts.

You're defeating the process here.

 

[CaryHenry]

I believe TB4 is on the sheet metal wall behind the S8 phase selection switch. You will need to remove the operator control cube roof to get to it.

You should buy a couple of cans of a high quality deoxidizing spray to aid you in getting this machine going. The S1 may not be bad... might be, but may also just have internal corrosion. This stuff works great: https://www.amazon.com/Hosa-D5S-6-DeoxIT-Contact-Cleaner/dp/B00006LVEU

You will want to hit every single switch, open contact, terminal board, etc (with the batteries disconnected) and articulate every knob and switch until you are bored.. then a few times more.. This will free up many issues, and get a good future corrosion inhibiting layer into the contacts.

Thank you very much. All the wires that are giving me trouble are on TB4. I'll pull the cover and start probing with the multi meter. I appreciate your recommendation on the deoxidizing spray and will get some ordered. Thanks for your help!

 

[Guyfang]

If you have no power to S1-3 in the start position, then your gen set will never run. Get a new switch.

And I have to ask, is S10 in the run position?

 

[Farmitall]

Thank you very much. All the wires that are giving me trouble are on TB4. I'll pull the cover and start probing with the multi meter. I appreciate your recommendation on the deoxidizing spray and will get some ordered. Thanks for your help!

Before you start probing with a multimeter, grab a good bright flashlight and an illustration of TB-4 and go from one end of it to the other, checking the wire numbers to make sure the right wires are on the correct terminal.


NOTE: This area of these generators is also a favorite of mice for building nests. Don't be surprised if you open it up and find it stuffed full of nesting materials.
Not only do they nest there, they piss and crap on anything and everything. They are disgusting, destructive little SOBs.

If you find that to be the case, DISCONNECT YOUR BATTERIES, then get a vacuum cleaner with a crevice tool end on it and thoroughly clean out the area, being careful not to break any wiring, then use an old toothbrush and some "NON CHLORINATED" electronics cleaner spray, OR some 90% Isopropyl Alcohol.....or some straight grain alcohol (tax paid moonshine) in a spray bottle and clean the place up.

Any terminals that might be badly soiled or corroded should be disconnected, cleaned with a nylon/plastic brush and spray and reconnected. The reason I suggest nylon/plastic is so that stray conductive metal bristles aren't floating around in there, just waiting to be a problem.

After you check out the wiring numbers and they are correct, you'll want to check the tightness of the terminals.

Oh, and Wash your hands when you're done.

 

[CaryHenry]

Before you start probing with a multimeter, grab a good bright flashlight and an illustration of TB-4 and go from one end of it to the other, checking the wire numbers to make sure the right wires are on the correct terminal.


NOTE: This area of these generators is also a favorite of mice for building nests. Don't be surprised if you open it up and find it stuffed full of nesting materials.
Not only do they nest there, they piss and crap on anything and everything. They are disgusting, destructive little SOBs.

If you find that to be the case, DISCONNECT YOUR BATTERIES, then get a vacuum cleaner with a crevice tool end on it and thoroughly clean out the area, being careful not to break any wiring, then use an old toothbrush and some "NON CHLORINATED" electronics cleaner spray, OR some 90% Isopropyl Alcohol.....or some straight grain alcohol (tax paid moonshine) in a spray bottle and clean the place up.

Any terminals that might be badly soiled or corroded should be disconnected, cleaned with a nylon/plastic brush and spray and reconnected. The reason I suggest nylon/plastic is so that stray conductive metal bristles aren't floating around in there, just waiting to be a problem.

After you check out the wiring numbers and they are correct, you'll want to check the tightness of the terminals.

Oh, and Wash your hands when you're done.

Went through TB4 and all the wires look to be in the correct location. I went to test the diode from 10-11, and it was showing 54 ohms no matter the direction. Got all excited and that we found the issue. Pulled the diode and it tested ~1500 ohm one way and open the other. Tested the resistance between 10-11 without the diode in place and got 54 ohms. If I'm reading the wiring diagram correctly, should that be an open circuit between 10-11 with the diode removed?

 

[Guyfang]

No. And you always test a diode by removing at least one end of it from the circuit.

 

[CaryHenry]

No. And you always test a diode by removing at least one end of it from the circuit.

Thank you!

I'm going through the diagrams, and it looks like 117A (the power for the fuel pump) gets traced back through the A9 float module switch, which appears to get its power from S1-5 at J7-8? So if I get power at P7-8, I need to check the float module switch?

I've also tried tracing 119B/D. It looks like both of these are supposed to get power from 119C on P7-6, which then feeds from 119E on TB5-2. There are several commons on TB5-2, but it looks like the only one that is not connected to a diagnostic port or alarm/fault is 119G. Via process of elimination, I assume this is where the supply voltage for these connections is coming from? Problem is, the wiring diagram in the TM I have doesn't say where 119G originates. Any help available?

Thanks!

 

[4x4nutz]

I bought an 803A 10K too. Will start and run awesome if I jump the starter, but otherwise will not start at the switch. The 30amp fuse capsule and the 30 amp fuse was missing from FU1, so I replaced them thinking it would fix the issue. Still won't start at the switch...it clicks, but power is clearly not making it to the starter...

 

[Light in the Dark]

I bought an 803A 10K too. Will start and run awesome if I jump the starter, but otherwise will not start at the switch. The 30amp fuse capsule and the 30 amp fuse was missing from FU1, so I replaced them thinking it would fix the issue. Still won't start at the switch...it clicks, but power is clearly not making it to the starter...

Do you have the color coded 10kw wiring diagram TM? Test along the starting circuit until you find the issue. Have you tested the cranking relay?

 

[CaryHenry]

I'm a little embarrassed to say I think I may have found the issue. Tracing the wiring diagrams, several of the nonfunctioning systems tie back to the relays. I've never owned one of these gensets before so the obvious isn't so obvious to me, but I'm missing the five K relays (12, 15, 16, 19, 20). I have the parts on order and hopefully the nce I throw them in, this bad boy will fire right up.

Still think my S1 switch is bad though since when I move it to start, I lose power on terminal 3. Problem is those dang switches are $300 now. If that's the only issue, I'll leave it in prime/run and jump the starter by hand.

 

[4x4nutz]

Do you have the color coded 10kw wiring diagram TM? Test along the starting circuit until you find the issue. Have you tested the cranking relay?

Probably going to have to hire someone to do that.

 

[Light in the Dark]

Probably going to have to hire someone to do that.

I think you need your own thread on this, is if doesn't already exist. Anyone can test almost anything in these machines if they have three things:

1.) Appropriate Technical Manual
2.) A handheld multimeter
3.) Eyes, Ears, and Hands

Even the third may be optional, but helpful. For the 803A, I reference ARMY TM 9-6115-642-24 (starting on PDF Page 54) for troubleshooting on that set. Please find it and download it if you haven't already. There are two very boiled down pages for criteria to look for/test under the "ENGINE FAILS TO CRANK" condition. Going through the testing, step by step, as laid out, will be the only way to diagnose this issue properly. Believe me or not... the testing really isn't that hard if you read the steps. And you will have a better appreciation for not only the lengths they went through to design this machine AND the documents furnished for its up keep.... and you might just surprise yourself with a new set of troubleshooting skills learned.

If you cannot find the TM in question, just ask and I can get it for you. Its downloadable from the internet (including this websites Technical Manuals section here: https://www.steelsoldiers.com/#technical-manuals.95 )

 

[Light in the Dark]

I'm a little embarrassed to say I think I may have found the issue. Tracing the wiring diagrams, several of the nonfunctioning systems tie back to the relays. I've never owned one of these gensets before so the obvious isn't so obvious to me, but I'm missing the five K relays (12, 15, 16, 19, 20). I have the parts on order and hopefully the nce I throw them in, this bad boy will fire right up.

Still think my S1 switch is bad though since when I move it to start, I lose power on terminal 3. Problem is those dang switches are $300 now. If that's the only issue, I'll leave it in prime/run and jump the starter by hand.

Yeah its not going to do anything with those little plastic boxes missing. The leftmost unit is a switch, the rest are all identical relays. Hopefully you bought the right units.

 

[CaryHenry]

Yeah its not going to do anything with those little plastic boxes missing. The leftmost unit is a switch, the rest are all identical relays. Hopefully you bought the right units.

I hope so. I ordered KUP-14D15-24

 

[Light in the Dark]

Thats the correct relay for the 5 right hand units. The first (leftmost) position is a switch: SPS-100-88-21091

I would recommend Kurt Klopp's unit for the first position: https://steelsoldiers.com/threads/mep-802a-mep-803a-s14-relay-5930-01-396-2940-88-21091.200402/

 

[CaryHenry]

Thats the correct relay for the 5 right hand units. The first (leftmost) position is a switch: SPS-100-88-21091

I would recommend Kurt Klopp's unit for the first position: https://steelsoldiers.com/threads/mep-802a-mep-803a-s14-relay-5930-01-396-2940-88-21091.200402/

Thanks. Those units are priced way better than others I've seen. Fortunately, I actually have that one. Only needed the cheap relays for the five other positions.

 

[4x4nutz]

I think you need your own thread on this, is if doesn't already exist. Anyone can test almost anything in these machines if they have three things:

1.) Appropriate Technical Manual
2.) A handheld multimeter
3.) Eyes, Ears, and Hands

Even the third may be optional, but helpful. For the 803A, I reference ARMY TM 9-6115-642-24 (starting on PDF Page 54) for troubleshooting on that set. Please find it and download it if you haven't already. There are two very boiled down pages for criteria to look for/test under the "ENGINE FAILS TO CRANK" condition. Going through the testing, step by step, as laid out, will be the only way to diagnose this issue properly. Believe me or not... the testing really isn't that hard if you read the steps. And you will have a better appreciation for not only the lengths they went through to design this machine AND the documents furnished for its up keep.... and you might just surprise yourself with a new set of troubleshooting skills learned.

If you cannot find the TM in question, just ask and I can get it for you. Its downloadable from the internet (including this websites Technical Manuals section here: https://www.steelsoldiers.com/#technical-manuals.95 )

Will look for a multi meter next time I go into the city. I have been jump starting the starter to run my water well when needed. Thank you.