Yamaha speedo tube clogged

[jscheetz]

I own a 2002 40 hp four stroke Yamaha. The speedo does not work, and I have narrowed the problem to the section of tube that has a barb connection behind a cowling on the lower unit and runs (I think) into the water pickup cavity. Does anyone know if this tube can be removed from the top? I can't beleive that I would have to drop the lower unit to fix this, and I just don't want to start pulling on it without knowing.<br /><br />Thanks,<br /><br />Jim

 

[thefishingfreak]

Re: Yamaha speedo tube clogged

there is a tiny hole on the cutting edge of the lower unit. clean it out with a tiny drill bit bye hand.<br />it's very small like 1/64"

 

[jscheetz]

Re: Yamaha speedo tube clogged

Thank you.

 

[kavika]

Re: Yamaha speedo tube clogged

1997 200 SWII<br />How accurate is the speedo and mile log on the Yamaha digital insturments?

 

[Greenwing]

Re: Yamaha speedo tube clogged

Be very careful with a drill bit make sure not to get it into a bind or it could possibly break because you will be using such a small bit I learned that lesson the hard way. They are not to accurate, mine varies 1-3 mph off according to a GPS dont know about the tripometer never checked that.

 

[Triton II]

Re: Yamaha speedo tube clogged

Hi kavika. I have a FT60B and it is within 1 knot above 10kts, but is very sensitive to how clean the pickup is (i.e the tiny pitot hole in the bullet of the lower leg) at slower speeds. So it seems from seeing this topic before that some are pretty accurate and others are not. I checked mine against a GPS both with and against the current to check. I take little notice of the mileage side of the thing, so can't help on that side of it.

 

[swist]

Re: Yamaha speedo tube clogged

Just use the drill in your fingers, or at most, a small hand chuck. If you break it off you will have no choice but to do it again and push the broken end into the pickup chamber (I've had one sitting there for years with no problem). <br /><br />It looks to me like taking the outdrive off does nothing for you - the pitot hole leads to a small closed chamber (to which the pickup hose attaches) It is part of the lower unit casting - there is no way to get inside it.<br /><br />The arrangement is mickey mouse, the pitot hole is just asking to be clogged, positioned where it is.

 

[swist]

Re: Yamaha speedo tube clogged

Oh yeah, and one piece of engineering trivia - it actually doesn't matter what the diameter of the pickup hole is as it is only measuring pressure (not flow). Same principle if you hook a #6 wire or a #26 wire to a voltage source, a voltmeter will read the same at the end of both wires.<br /><br />So if you wind up enlarging the hole it won't affect the (already inaccurate!) readings. The idea of it being so small is keep crud out but as we have seen, it doesn't succeed at that!

 

[GurdMar]

Re: Yamaha speedo tube clogged

So how did you end up fixing this problem?<br /><br />I have a similar problem with my Yamaha 115 4 stroke. The speedo doesn't work at all and I think it is a blocked tube.<br /><br />I have tried cleaning the lower end of the tube just before it enters the small closed chamber as suggested with a paperclip and drill bit but to avail.<br /><br />I tried blowing into the barbed connection of the tube ( lower gearcasing area - towards the small closed chamber) and it seems very hard / blocked. Blowing in the other connection ( towards the speedo ) seems OK ( air can pass ).<br /><br />What can I do???

 

[mark n dark]

Re: Yamaha speedo tube clogged

what ever you do dont try to blow compressed air into the end at the speedomter i did and blew the line off down in the lower unit that now has to get pulled

 

[Ray Neudecker]

Re: Yamaha speedo tube clogged

Best thing you can do is get a GPS and forget that pitot hole. The frustration of spending an hour getting it cleaned out and having it clog back up in 10 minutes will get to you before long. Boating is supposed to be fun. I can't seem to find any fun in getting down in a position to clean the thing out and having it clog right back up. May just be old age that gives me that additude.

 

[douglloyd]

Re: Yamaha speedo tube clogged

I had the same problem on my 115. I just bought a speedo pickup and some hose. Screwed it to the transom and that did the trick.

 

[petehublein]

Re: Yamaha speedo tube clogged

Yes you could pull it out of there but you wont get it back on unless you drop the bottom half off...Dumb i know...I just fixed my 40hp yamaha. I play guitar and used a old G string to ram the gunk out of there from the top down. Then from the bottom. I also sprayed simple green into the tube from the top down to help out. I also used a 4" piece of pilot tube to blow into the hole at the connection. If you dont play guitar, at wallmart you can get strings for about 3.50. good luck