Speed sensor help please

[froggy6916]

Hey guys, was wondering if anyone could help me. i bought a 1986 glasstream bass boat this year. cant get the speedometer to work have replaced everything (hose, gauge, and speed pickup sensor) and yet still it is not showing any movement when in the water, maybe it is mounted in the wrong place? here are some pics, if anyone could point out any problem or a diferent mounting location that would work, please feel free to copy and modify the pictures to show me where to mount if nesessary. i have no idea where it was mounted from factory but this is where it was when i bought it . thanks

 

[kaldeh]

Re: Speed sensor help please

The pickup is in line with the step in the hull my guess is that it is out of the water when you are running at speed. I would try moving it to the right away from the step.

 

[foodfisher]

Re: Speed sensor help please

Concur

 

[froggy6916]

Re: Speed sensor help please

Would you put it by circle number 1 or 2?, by circle number 1 it is still by the step in the hull and by circle number 2 it is at an angle.

 

[foodfisher]

Re: Speed sensor help please

#2 w/a wedge to point it forward.

 

[UncleWillie]

Re: Speed sensor help please

+1.

#2 ... Or if there is room, put it ON the STEP.
It needs to be in clean water. At speed, I would bet it is in the water but the water is full of air.
Don't expect to see much of an indication below 10-15 mph.

 

[Maclin]

Re: Speed sensor help please

Does the outboard have any provision for the pitot?

 

[froggy6916]

Re: Speed sensor help please

I guess i will be drilling holes and mounting it on the step, just gonna have to be real careful when loading the boat, so i dont break the pitot. just cant figure out how the factory mounted it. and as far a i can see, the motor doesnt have anything to mount it. it is a 86 mercury v6 135hp blackmax. oh, and mounting it on the step would mean that it will be pretty much in front of the engine. dont know if that will affect anything

 

[generator12]

Re: Speed sensor help please

I agree that it's not mounted so that it can work. The turbulence in that location will likely eliminate the water pressure needed to operate the speedometer, which is simply a pressure gauge.

If you have a small compressor, you can disconnect the line and jam it into the compressor outlet to see if the speedo moves. I think you would see something like a 30 mph indication with about 20 PSI on it. But the numbers are not the important item with this little test. It's the fact that it will test both the tube and the gauge. If you get any significant movement, chances are it's all okay and all you need to do is move the pitot tube.

 

[froggy6916]

Re: Speed sensor help please

Yup, i can get it all the way to 65 with the compressor. thanks

 

[UncleWillie]

Re: Speed sensor help please

Just for your reference...

2 psi = 17 mph (Typical pressure produced by a set of health lungs.)
6 psi = 30 mph
11 psi = 40 mph
24 psi = 60 mph
90 psi = 116 mph and Damaged Speedometer and Hoses!

 

[BRICH1260]

Re: Speed sensor help please

Yep, need to relocate the pick up so that it gets into "clean water".