MEP- 002a losing 24v power at start-up?? POWER ISSUE SOLVED!

[Cm131]

Hey guys brand new member. Didn’t even know this group existed until I was Googling for advice on the issue. I have a MEP-002a that is having an issue that I can’t seem to find the problem.
I lose 24v power when I try to start the set or just bump the starter. After I lose the power I have to bump the starter several times to get it back. Once I have the 24v back it will stay as long as I don’t bump the starter or attempt to start the unit?? I have cleaned and checked the following:
Starter connections
Starter Solenoid
Battery
Glow plugs
Fuel pump connections

Not sure what to check next or where to meter. Any help would be greatly appreciated. I bought this unit about 3 months ago not running but have since gotten it running mostly due to bad fuel just sitting in it. I am waiting for my new VR and capacitor to show up as it looked horrible. I was unable to test it at the time. So I just went ahead and bought one. Also unit appears to have been made in 89 but possibly someone put a new control panel box on it at some point as it’s a different color altogether. Not sure if the year of it.

 

[Light in the Dark]

So I assume you have put a multimeter on the batteries, to confirm you have at least 24V present? Step two of that, is to have them load tested at an auto parts store. You might have surface voltage, but NO amperage when it comes time to crank (meaning the batteries are malfunctioning).

The 24V present at the starter coming and going may be a sign of another intermittent connection issue. I'd question the batteries first.

 

[Cm131]

So I assume you have put a multimeter on the batteries, to confirm you have at least 24V present? Step two of that, is to have them load tested at an auto parts store. You might have surface voltage, but NO amperage when it comes time to crank (meaning the batteries are malfunctioning).

The 24V present at the starter coming and going may be a sign of another intermittent connection issue. I'd question the batteries first.

Thank you for the suggestion. The battery’s are one week old. I have tested them with a MM and get proper voltage. I have also load tested them as well just to confirm. When the unit was running I have also tested to make sure they were supplying correct power. I believe I was getting around 27-28v.

 

[Light in the Dark]

I would say you may have a short in the solenoid possibly, if all connections to it are sound. I believe on the 00X machines, there is a 'new' and 'old' style starter. Might not hurt to share a photo of what yours has for the air cooled gurus to take a gander at.

 

[Cm131]

Ok o will do. I believe it’s the old style. It also appears to have had a new solenoid put on it at some point. I have confirmed power to all of those connections and have taken the starter of to clean all connections and put back with same results.

 

[Light in the Dark]

@jamawieb and @Ray70 ... either of you chaps have any thoughts here?

 

[Chainbreaker]

Definitely sounds like an intermittent issue. Since its starter related it sure sounds like it could be due to the "Starter Lockout Switch" and its adjustment.

Have you downloaded the TM's for the MEP-002a yet? They are under the Top of this page under "TM". In the parts manual you can find the Starter Lockout Switch, there is an adjustment that can be made. Can't remember the exact details but it's pretty easy to adjust the starter contact switch. You will have to take the cover off the lockout switch, which sometimes is a bit tricky because of the small clearance to the Shutoff Solenoid.

 

[Cm131]

Thank you for the help I do have the manual. I should have also said I can start the unit over all day. Never lose power to the starter. If that matters. Seems to only be 24v after the connections in the panel. I have 24v to the switch at the other settings as well. And to the lights.

 

[Chainbreaker]

The other thing to check is the "Chassis Ground Straps", there is one from the Control Box (look under the box bottom) that can cause the type of issue you are describing. There is also one from the engine block to skid frame. If they get a corroded or loose or the braid goes bad that can cause intermittent chassis ground and the type of problem you are experiencing.

 

[Cm131]

I have checked the front one at the engine. It seems to be flowing freely. I also checked various places around the engine and frame. I have not checked the one to the box as I assumed if it was not good I wouldn’t have lights are gauge movement. But I will add that to the list of things to check. Thank you.

 

[Cm131]

Also it is not popping the dc breaker.

 

[Cm131]

Just confirmed the ground strap at the box is good.

 

[Cm131]

So basically to me it seems everything is working as it should with the exception of losing power to the fuel pumps and glow plugs intermittently. I was thinking there may be another relay/capacitor in the electrical box that sometimes works and sometimes don’t if I bump the starter. Any other advice is appreciated.

 

[jamawieb]

Really sounds like the master switch. Do the panel lights still work when nothing else will?

 

[Cm131]

Yes the panel lights will work all the time. The only thing I lose is glow plugs and fuel pumps. The solenoid on the aux pump also always works.

 

[Cm131]

Is there a way to test it? I just goggled a new switch earlier and didn’t come up with a replacement and don’t know anyone that has one of these machines.

 

[Cm131]

Im not outside at the unit right now but if I remember correctly today when I was testing I had power up to the number 13 terminal ( the one for the fuel pump) on the switch but then I would lose it when I bumped the starter. So I believe when I have the 24v power the switch operates like it should.

 

[Ray70]

Take a look inside the control panel at the terminal block on the back wall. The 24V comes in from the stud on the starter and branches off to a couple different spots on the terminal block.
You may have a bad connection at one of those spots.
It's pretty easy to follow the 24V through the box using the wiring diagram.
There is also a square black diode attached to 2 of the screws ( CR3 ) which is part of the cranking power circuit.
Another diode ( CR1 ) is attached to the A1 board in the rear upper right corner of the control panel, that is also part of the cranking circuit.
Might want to test those as well, but sounds like a bad connection or a dirty relay contact to me.

 

[jamawieb]

Is there a way to test it? I just goggled a new switch earlier and didn’t come up with a replacement and don’t know anyone that has one of these machines.

Yes look at the manual and it will tell you which numbers have power at differwnt positions. Just take a multimeter to check voltage

 

[Cm131]

Will do thanks. I just checked because curiosity got the best of me. When I have power I’m getting 25.40 volts to the switch terminal 14 on master switch. When I bump the starter and loss the power I only read 5.14 volts to the switch. Is there a good better or best diagram. The one I’m using isn’t great.