Which terminal at the regulator has the 14V? If the "Bat." terminal is showing that voltage the problem is between the regulator and the battery, possibly an internal open circuit at the ammeter. Temporarily, remove all the wires from the ammeter and bolt them together. If the voltage rises at the battery terminals, replace the ammeter.

There are several other possibilities. You really need to find someone who can do a detailed circuit trace, as it's almost impossible to cover all the possible problems long distance unless you have an extensive background doing electrical work.
The "new wire harness" concerns me- - - -there are a lot of ways to get a wrong connection.
Jerry


"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!