Speedo and trim gauge question

firemedicjoe

Cadet
Joined
Aug 2, 2013
Messages
16
Hello all. I have 2 gauges not functioning properly on my new (used) boat. The speedo works but starts out at 30 and goes to about 40. The other one is the trim indicator. When you lower the boat trim the gauge works until you get about 3/4 of the way down then it pegs and reads that it is up. The question is, is it the gauge or the sensor? I have been looking for replacement gauges but they must be obsolete. Any help would be great!!!
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Joined
Oct 22, 2007
Messages
2,598
Re: Speedo and trim gauge question

It's possible the speedometer has a plugged tube leading up from the pitot, I'd check that before replacing the speedometer. Disconnect the tube from the back of the speedometer, if the reading drops down to 0 you had a plugged tube, if not then it's the speedometer.

As far as the trim gauge, it's more than likely a bad trim sender. They tend to fail a lot. If you can figure out what wires are coming from the trim sender (there's probably a connector somewhere) you should be able to measure the resistance and see if it varies smoothly as it goes through it's range of motion. Chances are the resistance will jump around, indicating that it's bad.

edit to add: As far as replacement gauges, they're pretty generic. Several manufacturers make gauges that should work. The only thing that's the least bit special is the trim gauge, different engine manufacturers have different resistance ranges for the senders. You just need to get a replacement gauge or sender to match the engine manufacturer. And while they may not match your existing gauges exactly, there are plenty out there which are close enough that it wouldn't be noticeable.
 
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Joined
Oct 22, 2007
Messages
2,598
Re: Speedo and trim gauge question

Not bad, at least on the Johnson/Evinrude outboards I've had. They're just held in place with a couple of screws, and then you have to hook up the wires. Other manufacturers I can't vouch for, but it's my guess it would be similar. Get some pointers from the appropriate engine repair forum here if you need help on that.
 
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