[cheroot]

I have a 1990 international 4600 series truck with a 7.3 litre non turbo engine and the starter motor engages intermintantly while driving any ideas?

[TxGreaseMonkey]

. Faulty ignition switch? Check for wear.

. Faulty starter solenoid? Vibration causes the relay to make contact.

It shouldn't be difficult to solve.

[Stratmando]

Not sure your vehicle, many starter solenoids get power from Ignition switch, and the ground of the solenoid usually goes through safetys and interlocks. I would say the Ignition switch may be the problem or the starter wire is touching a live wire?