Speedometer not working

[vince champion]

Hi, I have a 1989 Champion bass boat with a 175 mercury EFI on it. On back of my transom Has the spinning wheel for my speedometer. But i check behind my speedometer it has the Air tube. I understand there are 2 type of unit that can connect to your speedometer. is this weird? Did the ex owner messed things up? thanks in advance.

 

[DJ]

Re: Speedometer not working

Your speedometer is of the pneumatic type. Yes, it needs an air tube attached.

Your Mercury should have a connection, for the tube, on the front of the lower unit just above the cavitation plate.

 

[Silvertip]

Re: Speedometer not working

The paddle wheel is the speed transducer for the fish finder. If the tube is connected at the engine, the small hole at the front of the engine may be plugged with debris. A pin will clear it out. Very common problem. If that's clear, then the tube may be pinched.

 

[vince champion]

Re: Speedometer not working

Thx for your reply, Can someone please post a picture of where the hole is at? Where am i suppose to unclog the debree out of the hole? Thx again.

 

[Silvertip]

Re: Speedometer not working

I don't have a picture. Follow the tube to the engine. There is a fitting on the forward side of the lower unit in the area of anti-ventilation plate. It is what the tube attaches to. The small hole faces forward. Otherwise disconnect the tube and blow some air through it -- not towards the gauge, toward the fitting.

 

[vince champion]

Re: Speedometer not working

Thanks for your help, this may be a stupid question but the speedometer need a positive and negetive wire attach to it? Since it runs on pressure. and thanks for your help again.
p.s I have a teleflex gauge.

 

[mrmushroomman]

Re: Speedometer not working

I would use a small drill bit to unclog the hole. If you use a pin it will just push what ever is clogging further in the hole. The drill bit will grab the debre and if you spin the bit in and out will pull the debre out a little better than a pin but both will work.

 

[Silvertip]

Re: Speedometer not working

The positive and negative electrical connection is for the internal light and has absolutely nothing to do with the function of the speedometer.