Re: Electrical (I hope) problem - any ideas?
I have not actually come across the Problem on an Alfa, But Similar problems have occured on other vehicles. A Battery would not Usually cause that sort of problem, ( unless it went completely open circuit and the voltage went sky high ) As long as the battery has enough power to start the car, it should be good enough to operate anything else on the car. It could be a charging problem, so it worth connecting a voltmeter into the car and watching that when the fault occurs. ( I sometimes plug one into the cigar lighter socket and let the customer drive the car till the fault occurs )
Otherwise it could be a faulty instrument panel, (Thats if it is a combined speedo and rev counter ) or wiring. Just another thought, it hasn't had any unusual spark plugs fitted recently has it. ?? ( electrical interference from wrong plugs can cause havoc with gauges and it would explain why its affecting both gauges.