MEP-003a Fuel Cut off Solenoid

[jamawieb]

I've got a unit that ran great until last week. When I went to start the unit, it would not start due to the fuel cut off solenoid not disengaging. I've taken the solenoid off and it tested good. There is no binding and it easily disengages when 24 volts is manually applied. It's only me so I can't try to crank it and see what the voltage is at the solenoid but I have taken measurements from the control box when cranking. I took a measurement from pin 28 off the master switch . Per the TM, pin 28 sends direct current to the solenoid for the initial start to bypass the safety devices (ie. oil pressure, temperature gauge). The measurement there is 19 volts but my batteries are fully charged at 25 volts. This tells me that I have short somewhere but I can't seem to find it. I'm guessing since I only have 19 volts, that is not enough voltage to disengage the solenoid.
When cranking, the starter and fuel pumps are working good so it has to be a short in the initial solenoid bypass system because I would think that if it was a short in the system, the starter would not work either. I'm not an expert on the electrical schematic so I'm hoping someone else can help. I've been trying to figure this out all week.

 

[bchauvette]

It must be bad solonoid season. Took me 4 days 3/4 tank of fuel to diagnose a 24V over current issue. Shorting solonoid with heat. There are two interwoven coils It takes more ompf to pull the coil than to hold it. When the coil is pulled in a set of contacts open dropping one of the coils. check for power at the solonoid terminal master in the run position. Install the solenoid turn power on, master run position push the plunger in. If it holds you either have an open coil or a problem with the contacts. Actually there is constant voltage to the solonoid and engages to run

Take both nuts off the terminal being careful not to spin the studs. Lock 2 nuts to the top of the stud to hold the stud to loosen the bottom nut Pull the can off and inspect the contact. You may be able to clean up the contact. If the varnishing failed I wouldn't use that solonoid.

A replacement solonoid goes for up to $400.00 . I took off the solonoid and currently using a paint stir stick to shut the generator off, push down the fuel control arm. Currently in the process of fabricating a manual cut off. Turning out to be more of a challenge than planned.

I forget the terminal number on the master switch that feeds th shut off but it is the one that has two terminal strapped together facing inward with the box panel open. It feeds several components. There may be enough Resistance across the contact to prevent the plunger from pulling. From the switch it goes to TB4 and TB5. Ill see if I still have my notes.