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No speedo- 2001 Sunsetter lxi


asp13

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Finally got my new (to me) boat out over the weekend. The thing ran like a top and we have a blast all day on the water. Only thing that wasn't working was the speedometer. 

Any ideas why the speedo wasn't working or ways to fix it?

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does the needle buzz and twitch when you cycle the key?  If not, check connections.  If connections OK and you can validate it's getting power at key-on with a DMM, the servo may be hosed.  If no power, the MDC might be bad.

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2 hours ago, UWSkier said:

does the needle buzz and twitch when you cycle the key?  If not, check connections.  If connections OK and you can validate it's getting power at key-on with a DMM, the servo may be hosed.  If no power, the MDC might be bad.

Didn't notice any movement from the speedo needle. Whats DMM and MDC?

 

2 hours ago, John I. said:

Did you try the pitot selector switch? 

Where would I find that? (sorry I am a boat owner newb)

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1 hour ago, asp13 said:

Didn't notice any movement from the speedo needle. Whats DMM and MDC?

 

Where would I find that? (sorry I am a boat owner newb)

DMM Digital MultiMeter

MDC is the Medallion computer.  It's up under the dash and is identifiable by the two small tubes that connect to it for the speedometers.

Asking the obvious: the pitots are down and clean, right?

By your key you should have two rocker switches with arrows on them.  One is the left-right selector to select which input to display.  If it's in the middle it takes the highest of the two readings IIRC.  The up-down arrow is to adjust each individual input.  To calibrate, take a GPS out and run at a steady speed.  Then select one of the inputs and use the rocker to adjust it up/down until the gauge and GPS say the same.  Then repeat on other side.

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The pitot tube system just needs to go. Spend a little bit of money now to get a more accurate speedo that won't wreck the expensive Dash Computer.

First thing, cut off the pitot tubes to the Medallion Dash Computer (MDC) under the dash. You will need to bend the tubes over and secure them closed with a zip tie.  Go to the back of the boat and take the tubes off and plug the holes.   The pitot to MDC system will eventually fail and water will enter the MDC resulting in a failure of the MDC.  Water dripping on your feet from under the dash is the sign that you waited to long and that water has entered the MDC.   Replacing the MDC is Expensive.   

Second, get a GPS conversion kit.  Simple to install and you will have accurate speed.

You could wait like I did until I had to purchase an MDC (expensive) and then buy the GPS conversion Kit.

or you could upgrade the speedo to a Perfect Pass type unit, this would be the gold standard.

 

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20 minutes ago, Bozboat said:

The pitot tube system just needs to go. Spend a little bit of money now to get a more accurate speedo that won't wreck the expensive Dash Computer.

First thing, cut off the pitot tubes to the Medallion Dash Computer (MDC) under the dash. You will need to bend the tubes over and secure them closed with a zip tie.  Go to the back of the boat and take the tubes off and plug the holes.   The pitot to MDC system will eventually fail and water will enter the MDC resulting in a failure of the MDC.  Water dripping on your feet from under the dash is the sign that you waited to long and that water has entered the MDC.   Replacing the MDC is Expensive.   

Second, get a GPS conversion kit.  Simple to install and you will have accurate speed.

You could wait like I did until I had to purchase an MDC (expensive) and then buy the GPS conversion Kit.

or you could upgrade the speedo to a Perfect Pass type unit, this would be the gold standard.

 

I plan on getting perfect pass for next season. I have seen a few possible fixes including getting a small nail/drill bit into the pitot hole to clean out any possible weeds/grime/etc. Hopefully a few of those tips work for the rest of this season.

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35 minutes ago, asp13 said:

I plan on getting perfect pass for next season. I have seen a few possible fixes including getting a small nail/drill bit into the pitot hole to clean out any possible weeds/grime/etc. Hopefully a few of those tips work for the rest of this season.

you could use a speedo app on your phone or just drive by tach,  3000 rpm should be 30 mph etc

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26 minutes ago, Bozboat said:

you could use a speedo app on your phone or just drive by tach,  3000 rpm should be 30 mph etc

Yeah we were running based on rpm the first day. Wakeboarding felt good at 25-2600 rpm. Im assuming it was about 22mph.

What rpm would be in the 32-34 mph range for slalom? Prop on the boat currently is a acme 653 

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With the 653, it should be close to this:

32=3300

33=3400

34=3500

get yourself a speed app on your phone to verify.  I use Speed Box

Edited by Brodie
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On 7/17/2018 at 12:06 PM, Brodie said:

With the 653, it should be close to this:

32=3300

33=3400

34=3500

get yourself a speed app on your phone to verify.  I use Speed Box

Awesome, thanks. I just got a speed app that I will try next time I am out on the boat. So far is seems to be dead on with the speedo in my car.

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The pitots are unreliable. I pulled mine and did the GPS conversion. I also have the GPS perfect pass.

If those pitots leak and get up into the MDC...that will get expensive in a hurry.

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