Speedometer faded out ...

[ThorSen]

Good morning all!

I did a search first, didn’t find any answers and am putting this here as I understand the types of speedos differ from sport boats and outboards versus cruisers, etc.

Trying to find out why the speedometer on our 2018 SPX190 OutBoard (with 16 hours on it) gradually went out yesterday (as in the needle gradually read lower and lower even when we throttled up and were obviously moving faster; in other words, the needle did NOT just all of a sudden “plummet” to zero), it finally bottomed out at zero and then didn’t budge after that.

This occurred Sunday eve and we know the speedo was working aces Friday evening. We keep our boat out of the water on a lift at our dock when not in use.

It was getting late so we just returned to our dock and lift and everything under the dash “looked” in order (to a retired cop which could be scary! so, I am scratching my head where to look next.

The owners manuals for the boat as well as the Mercury 150 Engine do NOT mention troubleshooting anything even approaching this (we are contemplating on investing in tech manuals for both the boat as well as the Mercury outboard engine. We did this for the wife’s ‘66 GTO and those manuals have turned out to be good investments - when something “goes wrong”, Even if we aren’t up to more than changing oil, lube, sparks and Filters etc. it is always nice to at least have an idea what gremlin we’re chasing ... or seeking more expert assist in resolving)

Thanks in advance for any assist!

 

[BillK2632]

Most boat speedometers work with water pressure. A pickup is either in the engine itself (a little hole on the leading edge of the outdrive or outboard) or there is a transom mounted pickup. From there a tube runs to the gauge on the dash. As the boat moves, water is forced up through the tube which causes the gauge to move. It is common for debris from the water, leaves, weeds etc to clog the pickup - the fix is usually to use a small piece of wire or wire tie to clear out the clog.

 

[ThorSen]

Hey BillK2632, Thank YOU, buddy!

LOL, looks like I’m going overboard to get under the boat and motor as the floating lift we have holds the boat 4 feet or so above water level. (Oh well, it’s in the 90’s onmour lake so, nice day for it

The Admiral opines, “I’ll betcha dollars to donuts a d*mn spider crawled up in there. (Our dock is beset with the darn things this year as I did not spray everything down with vinegar yet this year but, as soon as I can get her to move the boat out, I am gonna rectify that too!

Thanks again sir!!!!

 

[ThorSen]

Turned out it was some dried up algae; more than likely from our raising the trim while learning how the vessel responded, etc.

The pitot on the current Mercury 150 4-strokes is on the front edge of the lower unit, immediately above the “cone”

I probably could’ve pinched it off of there with my fingers but had a wire with me so I used that (had it been wet a wire would’ve been absolutely necessary).

Now we know, as we’re hosing the hull off after the lift is raised,shoot a jet-stream of water at that pitot from the side, to ensure it’s clear of any micro-particulate debris.

Thank you, again!

 

[BillK2632]

Glad it’s all fixed, nice when it is something easy.