bravo III speedometer problem

paulswagelock

Well-Known Member
Oct 25, 2010
2,183
pa
Boat Info
2018 SDX 270 OB 300 Verado
Engines
Verado 300
All last season my speedometer was very sluggish to repond. It lagged the actual speed on the way up, and was slow to return to zero when stopped.

So over the winter I did the drill bit clean out in the lower unit leading edge pitot hole, nothing. I removed the tube from the top of the lower unit and used compressed air to blow back through the lower unit - air flowed freely out the pitot hole. Yesterday I splashed and went for a quick ride - problem still exists.

I have the Mercruiser Smartcraft gauges, so I do not think the actual air line runs to the speedometer, I assume there is a pressure sensor somewhere in the engine bay? Any one know what happens to the air tube that comes in through the lower unit once inside? I want to find it and use compressed air reversed to try to blow out something that must have made its way up through the sensing line somewhere above the lower unit.

Thoughts, recommendations?
 
Thanks. Looked up the pics and it shows where it should be inside my engine compartment. Also looked up the Smartcraft pitot sensor so i have a pic of that as well. Should be able to find that component, disconnect the tube, and try to blow air down through the entire passageway.
 
Thanks. Looked up the pics and it shows where it should be inside my engine compartment. Also looked up the Smartcraft pitot sensor so i have a pic of that as well. Should be able to find that component, disconnect the tube, and try to blow air down through the entire passageway.

The sensor should be attached to the relay plate along with some relays just behind the ECM on the inside of the Port Riser. I have a pic somewhere I will try to post.

You will be able to trace the Pitot tube from that sensor down to the transom assembly. There is a "quick disconnect" fitting that snaps on to the tube in the transom assembly.

Have you seen a Pitot fault?

I am having some issues with mine as well.
 
Here is a Pic. It is circled in RED. I took this pic for an article I wrote on steering sensor install so the pic is not a great one of the Pitot sensor.

finalwiredup.jpg
 
I have not had a pitot error, and it does work, just very sluggish. Picture is perfect, can see what I am looking for installed. Thanks.
 
Stopped by the marina today. I readily found the sensor and disconnected the tubing that runs into the outdrive. Tried to blow through it - plugged. Got my 12v compressor for bike tires and topoffs on cars, and put on an attachment that fit into the tubing for the pitot. It took several runs up to 40 or 50 psi, but on the third pressurization it let free. I was able to easily blow through it. Connected back up, and out for a spin. Works perfect again.
 
Stopped by the marina today. I readily found the sensor and disconnected the tubing that runs into the outdrive. Tried to blow through it - plugged. Got my 12v compressor for bike tires and topoffs on cars, and put on an attachment that fit into the tubing for the pitot. It took several runs up to 40 or 50 psi, but on the third pressurization it let free. I was able to easily blow through it. Connected back up, and out for a spin. Works perfect again.

I'm super new to boating and the nomenclature. Any way I can get these parts in dumb guys terms? I've looked everywhere on the BIII outdrive for an import sensor, and can see none. There is a hose? I would greatly appreaciate any help, b/c I'm sure I'm having the same problem.
 
I have the digital gauges called Smartcraft from Mercury, so I have a sensor in the engine compartment. If you just have regular gauges, the tube runs all the way to your speedometer. It would be a black tube about the size of a straw at the top port side of your transom assembly when looking from the cockpit of your boat into the engine compartment. You can disconnect it at the speedometer and pressurize there, or cut it in the engine compartment, clear it, and splice it back together with a small vacuum splice fitting from an auto parts store.
 
I am definitely going to try this fix. My speedo starred working intermittently last season.

Sent from my NookColor using Tapatalk
 
My speedo is also not working. Got out for the first time this season over Memorial Day Weekend. I have both traditional speedometer and a digital one via the smartcraft gauges, both not working. Would I have the Pitot sensor in the engine bay?
 
Yes, and both the gauge and the digital reading are driven from the pitot sensor. Do what I described a few posts earlier.
 
any idea of a part number for the sensor?
Is it from Mercury? Or from Searay??
 

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