Losing tach

I have an 02 196 gt40 ford and have been having problems where the tach will drop to zero and then begin bouncing around. The boat runs fine but when we are running through the course, perfect pass surges because it’s trying to get back to it’s set rpms. All the wiring on the back of the dash looks good. Any suggestions on how to fix? It usually starts the morning out great but after the first couple sets (30 minutes or so) the tach will drop off, but it doesn’t happen every day! Thanks for any insight.

Thanks. I read the thread which makes me realize I probably should have added more info (but I will look to see if the back of my gauge has that).

Thanks!

Now I just need to figure out where to go from here!

Since you bought the boat with PP which I guess we could assume was working and it had a dead tach and then you replaced the tach, is this when the issues started with PP?

Todd,

8122pbrainard wrote: Todd, Check the voltage the PP is getting especially when it decides to malfunction. Use a VOM and NOT the gauge at the helm.

What do you connect volt meter (I assume that’s VOM) to?

Tbarile wrote: 8122pbrainard wrote: Todd, Check the voltage the PP is getting especially when it decides to malfunction. Use a VOM and NOT the gauge at the helm.  What do you connect volt meter (I assume that’s VOM) to?

Tbarile wrote: I only have an analog multimeter so I’m having a digital One delivered tomorrow to make it easier. Also, this isn’t just an issue with perfect pass losing the signal, the Faria tach loses it as well. I spoke with a mechanics last night and he thinks it’s the gateway box. Thoughts?

Hey Pete, I’ve your looking for voltage spikes it’s time to break out the oscilloscope. I recommend tektronix. No DVM or analog voltmeter will show a spike.

DVskier wrote: Hey Pete, I’ve your looking for voltage spikes it’s time to break out the oscilloscope. I recommend tektronix. No DVM or analog voltmeter will show a spike.

Well Pete I have 2 years of US Navy electrical and electronic training and a 2 year technical college degree in Electrical Engineering Technlolgy and can guarantee that no one can see a voltage spike using anything but an oscilloscope. I believe your training is in mechanical engineering. For simple “static” testing of voltage, current and resistance a DVM is totally acceptable. Not trying to confuse or deflect anything. Twitch or spike, whatever.

Of course I have but it cannot be counted on. BTW I received my electrical/electronic training in 1965, no DVMs were in production at that time.

KENO wrote: Dave I think you have Pete twitching right now  Easy enough to find out how long a "spike" lasts. Not very long.............one billionth of a second. I think Pete has made up this "twitch" term. By the way Todd, back to our regularly scheduled programming, I don't think you have a Faria gateway box to have to worry about in your 2002. Key word being "think"

What is the box behind driver kick panel?

KENO wrote: Dave I think you have Pete twitching right now

Maybe it's a terminology thing