Stumped

[rcardin]

Starting issue. I have a M8540 Cab tractor that will start if I remove the fuel solenoid. Fuel solenoid tested at the battery works as it’s supposed to. Read voltage at the plug and got 12.81 volts with the key in on position, voltage drops to 8 volts and then steadily drops when key is turned off.(battery tested at 12.89). Tested solenoid
With plug and grounding body and nothing. What am I missing.

 

[North Idaho Wolfman]

Do you have the WSM?
That should give you a better idea of how to troubleshoot it.

 

[rcardin]

I do not.

 

[JimDeL]

Does that model have a timer relay that activates the solenoid?

 

[rcardin]

No sir, just a 30 amp fuse, a relay and the solenoid

 

[rcardin]

Changed out relay, didn’t need to it tested fine, the wires at plug maintain 12.7 volts even during full start. Actually it goes up to 12.8. Losing amperage somewhere, the lines don’t even arc when quick tapped to ground. Ran a wire from ignition switch that stays hot and everything works. Guess I’ll just put in a switch and remove relay, so old wires go dead. Was trying to find problem but jimmy rigging will do for now.