Speedometer Question ????

Shreve884

Cadet
Joined
Jul 23, 2005
Messages
21
I have recently purchased a 1978 Venture. The boat runs great, but none of the gauges were working.<br /><br />I traced the hot line from the ignition switch to the temperature gauge. There it is jumpered to the Trim Gauge and then to the tachometer. However, there seems to be no hot wire jumpered to the speedometer. I know it measures with air through the hollow tube, but I would have expected it need some kind of power input. Is mine just unwired or will the gauge run without power?<br /><br />Thanks!<br /><br />Oh ... also, my tube seems to be stopped up. Shouldn't I be able to blow through it?
 

Speedwagon

Petty Officer 1st Class
Joined
Jul 5, 2005
Messages
389
Re: Speedometer Question ????

If you think it is stopped up, blow compressed air in it FROM the speedometer side, out to the pitot side. Have both sides disconnected too. :) <br /><br />If it is stopped up, it won't work. I recently found this out myself while fixing mine.
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,771
Re: Speedometer Question ????

Speedometers require no power for operation. They work on water pressure (pitot tube). They only require power for the light.
 
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