Yamaha Digital Speedo Not Registering - The Hull Truth

PostOpus · 04-20-2008, 03:01 AM

The digital speedometer has decided to take a vacation. All the other functions in the display work fine, but the speedo only shows a dash (-) at all speeds. Fittings on the back of the gauge seem tight. I'm wondering if the problem might be the pickup on the engine, but I have no clue where to look. It's a Yamaha 115 Saltwater Series. Any suggestions?

TIA

A1 Outboard · 04-20-2008, 06:49 AM

Most likely it is a clogged pickup in the front of the gearcase, or on the transom if the boat uses the plastic pickup arm.

Look on the front leading edge of the gearcase, just above the bullet shaped nose, for a small tube or hole. You can use a drill bit with your hand or a pair of pliers to clean it out.

Removing the speedo hose at the front of the motor gives you a place to blow back and make sure it is free. If you have a transom mounted pickup, it's easy to clean or replace.

To check the gauge, use something like a Mighty Vac to apply air pressure after removing the hose. With the key ON, watch the gauge while adding air pressure to see if it reads.

PostOpus · 04-20-2008, 07:06 AM

There's no transom-mounted pickup. My outboard has a small hole just forward of the starboard-side water intake grill; would that be the speedo pickup? And is the tubing easily removable/replaceable from the lower unit without having to open things up much? (I haven't really studied it closely yet.)

{Bear with me...I'm used to inboards; this is my first outboard other than little kickers.}

Thanks for the assistance! I really appreciate it.

A1 Outboard · 04-20-2008, 11:36 AM

Quote:

PostOpus - 4/20/2008 9:06 AM There's no transom-mounted pickup. My outboard has a small hole just forward of the starboard-side water intake grill; would that be the speedo pickup? And is the tubing easily removable/replaceable from the lower unit without having to open things up much?

The speedo hole is on the very front leading edge of the gearcase, not on the side.

Look in the wiring and cables coming out of the motor to the transom well for a black rubber hose, about 1/4" diameter. It also may be in the front of the motor pan. There will be a plastic splice fitting that you can disconnect and blow back through the gearcase hole.

PostOpus · 05-05-2008, 06:34 AM

Partial success - - I finally located the opening on the gear gase (tiny little devil!) and tried cleaning it out manually with a super-small drill bit. Got a bit of what looked like hardened mud out of there. Took apart the splice and blew some canned air up toward the speedo, and it did register a speed. But blowing down toward the gearcase and in through the opening didn't help; it's still clogged somewhere in that lower unit. Do you think it might help if I shoot something like WD40 down from the splice, let it sit for a while, followed later by air? (I did have the boat back out on the water after the first attempts, and the speedo still shows nothing while running.)

TOTALLY UNRELATED: I'm concerned about the 10% ethanol gas that is the only thing available in my area; do you recommend any particular additive, and if so, at what ratio? Boat has a 42 gallon tank, which I believe is aluminum.

hyd-n-seek · 05-24-2008, 03:36 PM

Just got my boat out for the first time this season, and seems like I'm having the same problem with my Yamaha F250s. I'll try the drill bit, but two other questions:

1. Is there an easy way to locate/recognized the speedometer hose coming up to the motor from the lower unit?
2. Is there an easy way to actually get the speedometer to read off the GPS instead of the speed pickup?

Thanks.

PostOpus · 05-24-2008, 04:55 PM

1. Yes. On the front of the motor, it's a black flexible rubber tube, about 1/4" diameter, that follows the steering cables/wire harness from the transom to the motor, then splits off and goes straight down the front edge and enters the lower unit about 3 inches above the cavitation plate. Just before the tubing "disappears" into the lower unit, there should be a splice held together with two tiny cable ties; you can cut one of the ties to pull the tubing apart.

2. I don't think so; the GPS is electrical, the speedo is mechanical (operates on air pressure). But I have been known to be wrong on one or two occasions.

Jettyhopper · 06-28-2009, 01:50 PM

That was very helpful. Found mine and cleaned out some kind of fiberous material. Works great now.
Tip: Use some leader wire to clean out the small pick up hole, works great.