Fixing a speedo

[NZ-Kevin]

I'm working through all the bits that didn't work on my boat when I bought it. I've got to the speedo now, which is a "Smiths" and the part number is FVP5101. This wasn't connected to anything, but having read some posts here I realise there shouldn't be anything inside the tube on the back (at first I thought is should have a cable in it) and it is a pitot tube that connects to a sensor on the back of the boat. I can buy and mount a new sensor, but would like to know if the speedo still works first (before I spend money on the sensor).

I have tried blowing into the tube, with no effect at all. So I connected a foot pump off an air bed on to it. I can get the needle to move, but only to about 5mph. It seems to take an awful lot of pressure to move the needle. Does this seem right, or is it broken. If it's broken, can it be fixed?

Thanks
Kevin

 

[made in china]

Re: Fixing a speedo

I think you need to apply vacuum to it.

If you connected a pump to it, you may have damaged it.

 

[mike343]

Re: Fixing a speedo

No you need pressure. If the gauge moves its probably Ok and you will need a hose and pickup anyway--unless you just go to GPS.

 

[Fisherball]

Re: Fixing a speedo

The tube & sensor are cheap & you'll need them if you have to replace speedo anyway so you won't be throwing the money out if they don't solve the problem.