erratic tach

[nybor]

Hi. My tach operates for 8 seconds after starting the M35B engine, then drops to 0. After a short time (seconds) it jumps back up - works for a few seconds then down to zero again.

Has anyone had or seen this problem? I read somewhere that if the batteries were on float, an A/C power (from alternator) will not work?????

thanks
dave
\

 

[woodster]

check your wiring connections for corrosion and tightness

 

[Don Lucas]

I've had that problem. It was the tach itself because it has gotten some moisture in it.

I've also have the more standard problem of bad connections especially in the engine wiring harness connectors.

Before you get too caught up, do you know what is providing input to your tach (a sensor on the flywheel or a signal on the alternator)?