Avanti Tacho Problem

[davepink53]

Avanti Tacho Problem

The tacho in my 1971 Avanti 11 is acting strangely. As soon as I turn on the ignition, the needle goes all the way round past 8000 RPM and stays there until switched off. It has done this since I have owned it. Yesterday while out driving on the freeway, the needle started moving back and forward and gradually heading down to somewhere near it should be. Hit a bump, and back to the end stop again. It did not actually sit steadily on rpm, but moved around it for a short while, but now it's back to flat out. Any ideas? A bad earth perhaps. This car has been converted to right hand drive, so under the dash, it's all over the place

Thanks in advance,

Dave...

[Gunslinger]

I would guess a bad tach sender. It could be either a flat, round can or a square plastic box. Follow the wires from the tach to it. Replacement circuit boards are available through some of the advertisers in Avanti Magazine.

[davepink53]

Thanks Gunslinger, I have looked under the dash for the sender but have not located it. I guess that I will have to get a little more serious when I get under there again. I need some young bloke to check it out

[Gunslinger]

In a left hand drive car it would be attached to the steering wheel bracket. In a car converted to right hand drive...who knows? Is this an original tach or a replacement unit someone installed? If it's not original, there may well be no tach sender and it could simply be a bad tach altogether.

I know Corvettes of some years have a tach filter that can make it do weird things when they go bad. I'm not aware of Avantis of that vintage using tach filters, but one never knows after all these years.

[davepink53]

I have only owned the car for 2 years and as far as I know, it's the stock Tacho. But in 42 years, who knows what has been changed, It was one owner prior to me. Some time when the weather gets a bit better here, I will crawl up behind the dash and have another look.