New to the MEP-802a

[kiddra]

So after looking at the wiring diagram I realized I took measurements on CL2. I went back and re-performed measurements from post 13 and I got 24 volts on all readings.

 

[fa35jsf]

I'm in the process of updating the well plugs. I saw in the wiring diagram the low fuel safety feature so I used rags to put the floats at the full position but that did not effect the fuel pumps. Still nothing in PRIME/RUN

So the float for the gas gauge doesn’t do anything except the gauge. The low fuel light feeds from the funny S shaped pipe with two floats, particularly the lower. But if I remember right, as long as you DONT have the low fuel light then that shouldn’t be your problem.


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[Guyfang]

It’s simple. Put fuel in the tank!

I had the same problem recently where I thought I had a big problem because it wouldn’t crank and the pumps wouldn’t come on. Turns out the fuel tank was completely empty and it must have some sort of safety feature.


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The safety feature is FL-1

 

[Guyfang]

So the float for the gas gauge doesn’t do anything except the gauge. The low fuel light feeds from the funny S shaped pipe with two floats, particularly the lower. But if I remember right, as long as you DONT have the low fuel light then that shouldn’t be your problem.


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the funny s shaped thing is FL-1 and FL-2

 

[kloppk]

So after looking at the wiring diagram I realized I took measurements on CL2. I went back and re-performed measurements from post 13 and I got 24 volts on all readings.

OK, now we're narrowing down why you only get 5 volts at S1 2,4,6,8 & 3 when S1 is in Prime/Run.

Since you always have 24 volts at both ends of CR1 then there is an issue with getting the 24 volts from CR1 to S1.
Since you have 24 volts at S1 2,4,6,8 with S1 in the OFF and only 5 volts in the Prime/Run position it indicates there is a poor connection in the path from CR1 to S1-2.

Here is the wiring path to get the 24 volts from CR1 to S1-2.
CR1 pin 1 to wire 120B to J6-33
P6-33 to wire 120A to S10-2. (S10 is the Dead Crank Switch)
S10-3 to wire 133A to P7-14
J7-14 to wire 133B to S17-1. S17 is the Emergency Off Switch
S17-2 to wire 135A to CB1-2
CB1-1 to wire 136D to S1-2

To find where the problem is put S1 in Prime/Run, Dead Crank in Normal, EPO switch button out and measure the voltage all along the path above until you get to a point where the voltage drops from 24 volts down to 5 volts.

Do not disconnect J6/P6 or J7/P7 while measuring the voltages. If needed you can skip testing those points and just go to the other end of the wires to/from those connectors for now.

 

[Guyfang]

OK, now we're narrowing down why you only get 5 volts at S1 2,4,6,8 & 3 when S1 is in Prime/Run.

Since you always have 24 volts at both ends of CR1 then there is an issue with getting the 24 volts from CR1 to S1.
Since you have 24 volts at S1 2,4,6,8 with S1 in the OFF and only 5 volts in the Prime/Run position it indicates there is a poor connection in the path from CR1 to S1-2.

Here is the wiring path to get the 24 volts from CR1 to S1-2.
CR1 pin 1 to wire 120B to J6-33
P6-33 to wire 120A to S10-2. (S10 is the Dead Crank Switch)
S10-3 to wire 133A to P7-14
J7-14 to wire 133B to S17-1. S17 is the Emergency Off Switch
S17-2 to wire 135A to CB1-2
CB1-1 to wire 136D to S1-2

To find where the problem is put S1 in Prime/Run, Dead Crank in Normal, EPO switch button out and measure the voltage all along the path above until you get to a point where the voltage drops from 24 volts down to 5 volts.

Do not disconnect J6/P6 or J7/P7 while measuring the voltages. If needed you can skip testing those points and just go to the other end of the wires to/from those connectors for now.

I several times saw problems like this when the problem was in J6/J6 and J7/P7. Corrosion, and pins/sockets burnt because the plug was not tight, and a loose connection causes heat. So if your 24VDC is good before the plugs, and not after, do take a look.

 

[kiddra]

So I took voltages as directed above and got 24 volts all the way to CB-1 and realized that I had left CB-1 open over night. I closed CB-1 and voltage dropped back down to 5 volts. I backtracked the 5 volts all the way back to the left side of CR1. So now I have 24 volts on right side of CR1 and 5 on the left.

 

[kloppk]

Looks like CR1 is bad.

The part number for CR1 is 1N5406. It's a 3 amp 600 volt general purpose diode. Widely available for ~$0.50 each.

 

[kiddra]

Looks like I'll have to order one. Thank you so much for the help. I'll keep you up to date.

 

[kiddra]

So I get my replacement diode tomorrow but I am still waiting for the excite circuit fuse holder and MOV mod. If I want to test the motor out is there a way to disable the generator portion until I can finish my modifications?

 

[kloppk]

... If I want to test the motor out is there a way to disable the generator portion until I can finish my modifications?

Remove the wires to terminals 7 & 8 of the Voltage Regulator and put tape on each of the lugs so they can't touch anything or each other.
This will prevent the regulator from being powered by the generator heads quad winding.
* WARNING - The generator will still output ~120/240 volts when you have S1 in the START position! *
This is due to the field flashing operation that occurs when you initially start the generator.
Once you release S1 to the Prime/Run position the voltage output of the generator will drop to a much lower AC voltage.

Remember to hold S1 in the Start position until the oil pressure builds and displays on the oil pressure gauge.
Then you can release S1 back to Prime/Run. If you don't hold S1 in the Start position long enough the engine will immediately shut down.

 

[kiddra]

Thanks for your help. I'm hoping to have it up and running this evening after work. Would like to run it for 30 min or so. When I was cleaning things up yesterday I found a worn spot on the negative cable to the starter, I'm hoping this is what caused the CR diode to go bad. If not I really hope that I don't have any other grounds to find. I should have the rest of my modifications done by Monday depending on when I get the rest of my parts. Then I'll check out the AC side of the generator.

 

[Daybreak]

Howdy,

Drive a ground rod, and ground your unit.

 

[kiddra]

I installed my diode last night and disconnected wires to terminals 7&8 and she fired right up. Let it run for about 15 minutes or so to get up to operating temp or as close as I could get without a load. I did get a little white smoke at startup but it cleared right up. It appears that everything is working correctly on the motor side at least. It did catch me a little off guard when I shut it down and it took a little bit to coast down to a stop. I did verify on you tube that this seems normal. Should get my fuse holder today and my fuses on Monday. Hope to do a full test next week. Thanks for all the help and input.

 

[kiddra]

So everything came in the mail yesterday. I have the fuse mod and MOV mod installed. Fired her up and everything looks good. 120 on both legs. Thanks again kloppk for the MOV mod. Just need to pour a pad by the house to mount everything to, put a permanent ground rod in and connect to the house for a backup power in the winter. Thanks everyone for the help you saved me a lot of time.

 

[Daybreak]

Howdy,

in the field = ground rod driven and ground nuetral bar connected

attached to house = 4 wire connection = ground bar strap disconnected

You are then using your service panel grounding.

NOTE; load test your unit. Do not use your house. If things are not 100% right, things can be hurt. If that is the only way, turn off all breakers. Turn on only your stove. A stove is less likely to have issues if things go astray. and is a good balanced 120/240 load. To many folks have burned up wal-warts, garage controller and electronics if things are not right.

While load testing, watch the fuel return lines for weeping. Run a good 3-4 hours 75-100% load to clean it up. Good fresh diesel, and some additive for clean-up. While running, watch, listen, and inspect your unit to make sure things are good. Check your oil level periodically too.

Good luck.

 

[kiddra]

Daybreak thanks for the input. I don't really have a good way to load test so I had planned on turning off all breakers except the oven and let it do its 2 hour clean cycle. I'm not sure how much of a load that will put on the generator. I could turn on eyes to pull more power if needed. I have checked the voltage and sign-wave of the output power and all looks good so far. I also have replaced all return fuel lines so I will keep an eye on them as well. Fuel tank was cleaned and has new diesel. What kind of additive do you recommend? I have Seafoam that is diesel safe. I am planning on using a 4 wire connection. Not to start a new debate but would I benefit to use the house ground and have a grounding rod near the generator if it is not bonded to the neutral at the generator?