pem-804a

[kento]

hi guys,
thanks for the add, ive got an804a that wont start, and im having a difficult time following the wiring diagram.
if I put voltage to the wiring on the fuel shut off it will start and go to what seems like full throttle, any ideas? thanks

 

[patracy]

Moved your thread to the appropriate forum.

 

[Guyfang]

OK Partner,

Lets get started! Have you ever seen this set work right? Is it new to you? Or have you had it a while and it just started to not work? That was a strange sentence. Anyway, do you have the TM's? Have you read the troubleshooting diagram? What do you mean by "fuel shut off"? I can not find anything like that in the schematics. OH, by fuel shut off, do you mean the A-6, Electronic Actuator? Because if it is outfitted with an A-6, you do not have a MEP-804A, you have a MEP-804B. So maybe you could send a picture. Do you have fault indicator lights on that suggest a fault?

The balls in your court!

 

[kento]

this is a unit we purchased at auction, it has not run since we purchased it. the only info we have on it is the wiring diagrams on the doors and what we have downloaded from the web, fuel shut off is the electronic actuator. it seems the wiring harness from that actuator to the pin connector. is this something that may have been done before it was de commissioned ? from what we have figured this circuit goes to terminal 9 and 10 at the "ATC" on the blue box labeled A5, I apoligize for the lack of proper terminology, and really appreciate the help.

 

[doghead]

Lincoln?

 

[kento]

picture




first photo shows the actuator, second one shows the pin connector where we "think" we are missing the wires from, last 2 photos showing number plates on unit.

 

[kento]

Yes Sir

 

[Guyfang]

this is a unit we purchased at auction, it has not run since we purchased it. the only info we have on it is the wiring diagrams on the doors and what we have downloaded from the web, fuel shut off is the electronic actuator. it seems the wiring harness from that actuator to the pin connector. (I do not understand what you are trying to say in the previous sentence) is this something that may have been done before it was de commissioned? (No gen set is decommissioned. It may have problems, faults and missing parts though) from what we have figured this circuit goes to terminal 9 and 10 at the "ATC" on the blue box labeled A5, I apologize for the lack of proper terminology, and really appreciate the help.

Go to the manuals section of SS and download all the manuals. As far as I can remember, there were a few mistakes on the wire schematics on the gen set doors. So you can get good ones, in the TM section. Open the TM 9-6115-642-24 manual, at at the very back of the manual are the schematics. Then you can get the right terminology. The A-5 is the governor control unit.

Here is a couple of hints. The A-6, (Actuator) takes its signal from the A-5, (Gov) like you already figured out. BUT if the A-7, (Frequency transducer) is not sending the A-5 a signal, then the A-5 will not turn on the A-6, and that means the injector pump stays in a no fuel state. The A-7 is screwed into the side of the flywheel bell housing. It has two small wires pluged into it. Carefully unplug the wires. Remove the A-7. Using a multimeter, measure the two pins on the A-7. You should get between 800-900 ohms. If not, it is bad. Then look at the end that goes into the bell housing. Is it looking like it has been chewed up by the candy monster? If yes, get a new one. If no, then screw the A-7 back in, all the way till it bottoms out. Then screw it 1.5 turns back out. If you are somewhat miss trustful, like me, screw it two turns out. Then hand tighten the locking nut that should be on the A-7 threads. Have your wife or other TRUSTED friend turn over the engine with the S-1, (start switch), or the S-10, (Dead Crank Switch). At the same time you are to measure the two pins on the A-7 with a multimeter. Set the meter to read A/C voltage, (yes, A/C) What you want is between 2.5 and 3 volts A/C. For best results, 3 volts. To get that, tell trusted assistant to stop. If the voltage is low, turn the A-7 a TAD in, (CW). Then test again. If its two high, turn the A-7 out, (CCW). Do this until you are as close to 3 volts A/C as you can get it. Lock down the nut on the A-7, and try to start the set. Observe the A-6 to see if it moves and starts the set.

If its -40 below, or you have had a bad day and don't want to do all this, follow the next instructions.

a. Release control panel by turning two fasteners and lower control panel slowly.
b. Disconnect wire 147C from terminal 16 and wire 148C from terminal 17 of the A-5 governor control Unit.
c. Set multimeter for ohms and connect to ends of disconnected wires 147C and 148C. Multimeter should indicate
between 800 and 900 ohms.
d. Leave multimeter connected to wires 147C and 148C and set multimeter for AC volts.
e. Crank engine with DEAD CRANK switch and observe multimeter. Multimeter indication should be between 2.0 and
3.0 VAC.

Over to you!

 

[kento]

We checked the continuity on A-7, it was 775 ohms. We removed it, the end looked fine. We screwed it back in, set it, and checked a/c voltage, it's now 2.9v. The continuity between 147c and 148c was 7775 ohms. The a/c voltage was 2.9 v. Just wondering where to head next. Thank you

 

[Guyfang]

is 7775 ohms a typo?

 

[kento]

yes, 7775 was a typo it was 775 ohms

 

[kento]

is 7775 ohms a typo?

it is a typo

 

[Guyfang]

OK, is everything hooked back up right? If so, 0pen the control panel, look down at S-1, (start, run and stop switch) and make sure its hooked up IAW the schematic, insuring that the diode, CR5 is installed properly. Then, using your trusted helper, have them turn S-1 to the start position, while you measure for 24 volts at pins 3 and 7, of Start Switch, S-1. If you do NOT have voltage at pins 3 and 7 with the S-1 in the start position, S-1 is bad. If S-1 is good, then open Tm 9-6115-643-24, that you have hopefully downloaded, and go to troubleshooting, page 3-5. Start reading: 1. ENGINE CRANKS BUT FAILS TO START. You can disregard steps 1,2 and 4. Lets see what you get there.

 

[kento]

Sorry for my ignorance but I can not find TM9-6115-643-24.

 

[Guyfang]

Go to the top of the page.
Click on Forum.
At the top of the page is now Tech Manuals.
Scroll down to Generators, and click on it.
Go to page 2, and its there, All the manuals you need to work on the MEP-804A. Click on it. In that file, are all the books you need.
Down load them all, can't hurt.

 

[kento]

Got it, thanks

 

[Daybreak]

Howdy,
MEP-804A

All the TM's you need to work on the MEP-804A