mr475 Posted January 27, 2011 Share Posted January 27, 2011 My Quintrex runabout has a 70hp Yamaha 2 stroke engine and associated instruments on the dashboard such as speedo, tacho, trim, fuel, etc. However my speedo has stopped working. All fuses look intact under the dash and so do wiring connections. Question: how does the speedo read? There is no pitot tube so I am assuming the reading is done in the engine somehow. Do I need a new gauge or is it about some sensor in the engine that may not be working? Link to comment Share on other sites More sharing options...
NickF Posted January 27, 2011 Share Posted January 27, 2011 From what I understand there is a pressure sensor/tube in the leg of the outboard. These can get clogged etc and stop working. I use my GPS unit for speed readings as the one on the dash isn't 100% accurate. Get a can of Inox/Lanox or the like and stick the little nozzle inside the hole on the outboard and give it a blast to dislodge and grit and it should work again. Link to comment Share on other sites More sharing options...
oz_brett Posted January 27, 2011 Share Posted January 27, 2011 From what I understand there is a pressure sensor/tube in the leg of the outboard. These can get clogged etc and stop working. I use my GPS unit for speed readings as the one on the dash isn't 100% accurate. Get a can of Inox/Lanox or the like and stick the little nozzle inside the hole on the outboard and give it a blast to dislodge and grit and it should work again. I agree with Nick only with my old Yamy I would give it mouth to mouth and suck the debris out. I found this much better then pushing it further in. after a while I gave up worrying about it and continued using GPS. Link to comment Share on other sites More sharing options...
TheAlby Posted January 27, 2011 Share Posted January 27, 2011 I agree with Nick only with my old Yamy I would give it mouth to mouth and suck the debris out. I found this much better then pushing it further in. after a while I gave up worrying about it and continued using GPS. i got the same problem with my Yammie 70hp. Where abouts on the leg is the hole usually? thanks for the info Alby Link to comment Share on other sites More sharing options...
NickF Posted January 27, 2011 Share Posted January 27, 2011 Whay obey said, you wont miss it, the hole is quite small but clearly visible. I like to use Inox to blow all the grit out as it will dissolve any other unwanted grime in there. Link to comment Share on other sites More sharing options...
mr475 Posted January 28, 2011 Author Share Posted January 28, 2011 Thanks all of you for this info. I will have a look this weekend and see if I can fix it. This is another maintenace item I can easily attend to but need to be aware of, it seems. Bless you. Link to comment Share on other sites More sharing options...
garryl Posted February 7, 2012 Share Posted February 7, 2012 I've had the same problem with my 2002 Yamaha 115HP the last couple of times I went out. The info in this post helped me out, so thanks to everyone who contributed. For my contribution... Don't put your mouth anywhere near the port to clear it, especially if it's been blocked up for a few weeks. The water certainly gets putrid! After gagging a few times I had to come inside an take a couple of shots of OP Rum to try to kill the bugs that I'd stupidly inhaled. I'd be a little nervous breaking into the tubing to blow out the line the other way. My luck is I wouldn't get it back together and sealed up OK, or the tube or connections would start to crumble in my hands. I used a fine drill bit and dug out the muck, hoping that this is enough to clear it. I'm also a little curious about the use of Inox. I would have thought it would leave a film of lube inside the tube which might attract debris, or have an adverse affect on the plastic tube? Anyway, cross fingers next time I go out the speedo with work! Thanks again, Garry Link to comment Share on other sites More sharing options...
mr475 Posted February 13, 2012 Author Share Posted February 13, 2012 (edited) Thank you for all the suggestions, guys.(A long time ago, I know!) I tried Inox squirting down the tube, a broom bristle, fine wire but could not get it working. Even though I hate things not working on my boat, I think it is not worth fixing because it doesn't even register until 10 knots so is useless when driving in a 4 or 8 knot zone. So I have tuned in my Humminbird combo to read speed from the GPS and it reads speed to one tenth of a knot. This is really good because I was actually pulled over by the water police in an 8 knot zone one day but not booked because I was only marginally speeding and pleaded that my speedo did not register. Now I can show them my accurate speedo. And a GPS speed is a ground speed, not a water speed. I presume the speed limits are ground speed limits, not water speed limits. Doing 8 knots in the water against a 5 knot current would make for a very slow trip. Does anybody know? Edited February 13, 2012 by mr475 Link to comment Share on other sites More sharing options...
Bleeding Green Posted February 20, 2012 Share Posted February 20, 2012 Good question 475, I've always wondered about this. I'm interested to hear from those that know. Link to comment Share on other sites More sharing options...
GaryO Posted February 20, 2012 Share Posted February 20, 2012 Thank you for all the suggestions, guys.(A long time ago, I know!) I tried Inox squirting down the tube, a broom bristle, fine wire but could not get it working. Even though I hate things not working on my boat, I think it is not worth fixing because it doesn't even register until 10 knots so is useless when driving in a 4 or 8 knot zone. So I have tuned in my Humminbird combo to read speed from the GPS and it reads speed to one tenth of a knot. This is really good because I was actually pulled over by the water police in an 8 knot zone one day but not booked because I was only marginally speeding and pleaded that my speedo did not register. Now I can show them my accurate speedo. And a GPS speed is a ground speed, not a water speed. I presume the speed limits are ground speed limits, not water speed limits. Doing 8 knots in the water against a 5 knot current would make for a very slow trip. Does anybody know? If you are doing 8 knots against a 5 knot current you are doing an actual speed of 3knts , which is what you would be measured on. Link to comment Share on other sites More sharing options...
bisso Posted February 24, 2012 Share Posted February 24, 2012 8 knots is 8 knots.. it doesnt matter if you are going against or with the current... the speed limit is 8 knots so legally that is the maximum you can do. hypothetical, what if you had an 8 knot current behind you? Link to comment Share on other sites More sharing options...
tonez Posted February 26, 2012 Share Posted February 26, 2012 8 knots is 8 knots.. it doesnt matter if you are going against or with the current... the speed limit is 8 knots so legally that is the maximum you can do. hypothetical, what if you had an 8 knot current behind you? I would love to hear the argument between a boatie and the Maritime guy when that 8 knot current is going thru a 4 knot zone Boatie: "mate, i was in neutral being pushed by the bloody current, whataya want me to do...?" Maritime guy: "Its a 4 knot zone sir. You're the skipper, not the current. You could have had it in reverse to counter the speed of the current. Here is your fine". I would hate to think it is anything but actual ground speed. Link to comment Share on other sites More sharing options...
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