Yamaha guage doesn't show MPH

[bamaboy473]

We took the (new to us) 2005 Cobia with twin Yamaha 4S 150HP out for a test run. One of the few things we found was that the yamaha gauage that shows Speed and Distance don't display.
The Raymarine display is out of the boat and we thought that it might be the reason, but do these engines have a transducer/pickup for speed?

It doesn't sound right that the boat would need another instrument to display Speed...so where do I look and what do I look for?

[bossee]

Hi,

Assuming the speedometer LCD guage works and you use pitot in front of lower unit on the F150 as speed source it can be as easy as the intake tube is clogged. Use the thin wire and clean it out.

/Bo

[PostOpus]

I had the same problem. A very small diameter drill bit inserted and twisted by hand may clear it. Insert it in the VERY tiny hole indicated by the red arrow in bossee's post. I tested the gauge itself by snipping the cable tie (#32 in the diagram) and using a canned compressed air to blow air up toward the gauge with the key turned on. If you get a speed reading (mine showed 95 MPH !), the clog is definitely somewhere in the tubing inside the lower unit. After doing the drill bit routine, try blowing some air down toward the lower unit through the hose (#33) and see if you can feel air coming out the hole.

Do a search on "Yamaha speedo" ; you'll find several threads about the problem.

Good luck; this seems to be a VERY common problem with the Yammies.

[SturgeonLake]

FWIW, my authorized Yamaha mechanic has told me mine is toast. The muddy bay I live in managed to fill the hole with "cement" (his words) such that it can never be retrieved.

I've never had success with any speedo other than GPS in my 13 years here.

[bamaboy473]

GPS is a fersure nice way to get accurate speed, but it rankles me to have a new set of motors that don't do what their supposed to. Thanks for the diagram guys....looks like a project that'll go perfectly with the morning coffee!

[pastaman1234]

Mine had to be drilled out "under warranty" but now it works fine.

[ytmorris]

I quit trying to keep it going. I just use the GPS.

YT Morris