New Holland TN75 fuel solenoid starting issues

[9reaseMonkey]

after my old New Holland TN75 stalled due to a failed lift pump, I replaced both the pump and the fuel shutoff solenoid. Despite verifying the new solenoid functioned with 12v, the tractor would only start if the solenoid was left finger tight.

whenever I torque it down with a wrench, the engine won't fire. but if I loosen it, it runs perfectly. both the original and replacement solenoids measure identically on calipers, yet the machine is hyper sensitive to seating depth. has anyone experienced this, or is there a specific internal tolerance issue with non-stamped replacement parts?

 

[BaleMeOut]

Had a similar issue with a TN70 not too long ago. It turned out that the replacement solenoid didn't quite match the original specifications inside just finger-tight was enough to establish contact. Some of these non-OEM parts can be surprisingly flexible.

 

[Barnyardblues]

Faced that exact kind of hassle with an old NH loader. If I torqued it too much, nothing happened but when I just finger-tightened it, it started up right away. I learned that some aftermarket solenoids just don't handle being fully seated well

 

[Hayhunt]

Been through the same thing with a TN65. I measured everything and double-checked the wiring, but it turned out only a gentle hand-tight would work. It seems like some replacement parts have tighter internal tolerances or maybe they’re just looser, depending on how you want to view it.