There is probably a short in the high speed circuit. Finding that will probably fix it. The other long shot is if the system is too stiff at high speed as the motor labours to make it work it will pull more amps and may blow the fuse which means you will have to pull the rack to grease with new grease and probably wouldn't hurt to clean motor brushes and commutator. A shock to the electrical system can start the clock like touching/connecting the battery cable. There is a simple electronic mod you can make to the clock to make it reliable if you find it starting and stopping on it's own, Search the forum for the link.
TR7 Spider - 1978 Spifire - 1976 Spitfire - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra
