MEP003A Will only run in the "Start" position

[North Maine]

I just bought this unit... and it was started and tested in front of me before I bought it and all was fine... all gauges worked. He pulled his batteries, I trailered it home and let it sit for a month before getting around to working on it. I just installed two new batteries and went to test run it- the voltage gauge doesn't read anything at all, but it cranked and started great so I held the oil pressure toggle switch up and let the starter switch go to and it shut off instantly. No matter what I do with the Oil Pressure Bypass Switch it shuts down. I even jumped the oil pressure sensor with no luck. The unit builds 40+ PSI of oil pressure in less than 5 seconds.

Is there a fuse for 24V to the fuel shutoff solenoid or something else related to the 24V gauge that would allow the unit to start and run in the START position but instantly die in any other position?

 

[Guyfang]

I just bought this unit... and it was started and tested in front of me before I bought it and all was fine... all gauges worked. He pulled his batteries, I trailered it home and let it sit for a month before getting around to working on it. I just installed two new batteries and went to test run it- the voltage gauge doesn't read anything at all, but it cranked and started great so I held the oil pressure toggle switch up and let the starter switch go to and it shut off instantly. No matter what I do with the Oil Pressure Bypass Switch it shuts down. I even jumped the oil pressure sensor with no luck. The unit builds 40+ PSI of oil pressure in less than 5 seconds.

Is there a fuse for 24V to the fuel shutoff solenoid or something else related to the 24V gauge that would allow the unit to start and run in the START position but instantly die in any other position?

You need to get the TM's out and read them a bit. Learn the correct terminology. I have no idea what you mean by "I held the oil pressure toggle switch". So please find out the real name for it, and tell us.

This sounds like an engine safety problem. If you read the operators TM, it tells you that the S1, (Start Switch) bypasses all safety switches, during start up. Then, when the oil pressure is high enough and you let the S1 go, the engine will continue to run. So, normally, (but not always) when the set acts like you describe it, it is a safety switch. So, try this, in the below listed steps.
1. Start the set and hold the start switch up longer then you would "NORMALLY). Will it run now? If not.......
2. Go to TB5, (TB5 is a Terminal Board inside the control panel) and hook up a jumper wire between TB5-8 and TB5-9. This jumps past all the engine safety switches. Try and start the set. Will it run? If so, then its a safety switch. If not, let us know so we can go a step further.

 

[North Maine]

You need to get the TM's out and read them a bit. Learn the correct terminology. I have no idea what you mean by "I held the oil pressure toggle switch". So please find out the real name for it, and tell us.

This sounds like an engine safety problem. If you read the operators TM, it tells you that the S1, (Start Switch) bypasses all safety switches, during start up. Then, when the oil pressure is high enough and you let the S1 go, the engine will continue to run. So, normally, (but not always) when the set acts like you describe it, it is a safety switch. So, try this, in the below listed steps.
1. Start the set and hold the start switch up longer then you would "NORMALLY). Will it run now? If not.......
2. Go to TB5, (TB5 is a Terminal Board inside the control panel) and hook up a jumper wire between TB5-8 and TB5-9. This jumps past all the engine safety switches. Try and start the set. Will it run? If so, then its a safety switch. If not, let us know so we can go a step further.

It appears that the previous owner installed a By-Pass for the Low Oil Pressure Shut-Off in the form of a momentary toggle switch. Its not shown on the TM drawings and that explains why you had no clue what I was talking about.

1. I can hold S1 in the start position all day and the unit runs like a champ. When I let go- dies.

2. I will proceed with this next... however, I was wondering if the voltage gauge for the engine not being operation when it recently was operation was a significant clue or a red herring. I was hoping I had simply not connected a wire or had a blown fuse for this gauge to suddenly stop working.

I'll reply back with the test results.

 

[Guyfang]

You do NOT need a B.S switch for oil press by pass. If you start it right, there is no need for it. Holding the S1 in the up position bypasses the LOP, (Low Oil Pressure switch).

Try the jumper.

 

[Guyfang]

OH, the battery charging fuse is more or less up and to the right of the Oil filter. If you cant find it, tell me.

 

[North Maine]

Thanks for your help. The charging circuit fuse was blown, however a new fuse didn’t change any symptoms (still no run unless S1 is START and voltmeter is unresponsive for 24v system.
Jumping TB5-8 and -9 the unit stays running- so now I know it’s a safety switch. Are there more than the Overtemp and LOP?

 

[Guyfang]

No, Thats all. Unscrew one wire on the S5, (LOP) and screw it on the other terminal of the S5. Start the set. Will it stay running? If not, do the same thing with the S4.

Fix one problem at a time.

 

[Jericho]

Guy fang is absolutely correct , LOP low oil pressure switch was meant to protect the unit during extended run and from lazy GIs . Ninity nine per cent of lop switch problem if you had good indicated oil pressure was a bad LOP switch Easy fix

 

[Light in the Dark]

Ive replaced numerous LOP switches on the air cooled machines. Just connect the terminals together on it and refire like suggested above. I bet it will probably run right.