New Speedometer older engine

[tsmith]

I am replacing a bad speedometer with a "new" speedometer I purchased. The old engine is the '97 225 v76 Saltwater Series. The new speedometer I believe is a 2005. It does not have the switches on the back but a wheel that sets mph/kph/ etc. Is the wiring any different from the old gauge? So far the clock works correctly but nothing else. I used the same color coding as from the original gauge. Are there any simple tests that I could do to make sure the gauge is working correctly or wired correctly?

[Hamfisted]

Only the plugs changed after '94 so yours should swap out fine. Does your fuel quantity portion work? Does the gauge go through it's self-test when you turn the key ON ?


Mike

[tsmith]

The self test where everything lights up in the beginning seems to work fine. After reading through past messages on this board I tried two things that showed me that the new speedometer is working fine.

The first thing that I tried was going to the fuel tank and checking the connections to the sensor. The pink wire was directly connected to the center of a cap. A green and black wire were connected by spade connectors to what looked like a spot weld? just inside the edge of the cap. It came off of the spot weld in my hand when I went to check it. We cleaned up the connectors and touched it to the center post where the pink wire was connected. After 10 seconds, the fuel gauge started to read and in about 20 seconds or so it showed a full tank. When we tried touching this same connection to the hex head screws on the outer edge, the cap itself, or the previous spot weld spot, we recieved no reading. My gut tells me that the fuel gauge sensor needs replacing. Is this a good deduction?

The second thing we tried after reading through the speedometer posts on this board, was to check out the speedometer tube. We disconnected it from the back of the speedometer and the outboard. We blew threw it and expelled water that had gotten into the air tube. We then reconnected the tube back to the speedometer. With the aid of a hand pump, we sent air up the line to the speedometer. The speed indicator started working right away. When we tried to use the hand pump to send air through the outboard, we did not see any bubbles coming out the leading edge or anywhere else. I read that the hole is 1/16th diameter. It would be nice to find out exactly where the hole is. There seems to be two on one side and one on the other. If you could supply a detailed instruction as to where it is, it would be greatly appreciated.

In addition to the speed and the fuel registering on the speedometer, the trip gauge started with 0.0 where nothing was displayed before. So it looks like the gauge is working.

Looking forward to your reply.

[Ken]

tsmith,
The speedometer pickup hole is located on the leading edge of the lower unit. On my 2000 C115 it is about three inches above the center of the round part of the lower unit that is the gearcase.
This hole gets plugged up very easily and needs to be cleaned out every so often - I use a small diameter drill bit - you want one that is a little smaller than the hole - you don't want to make the hole larger, just clean it out.
After cleaning out the hole, you can blow back thru the tubing to see if the hole is cleared - disconnect at the bullet connector where the tubing comes out of the upper casing and try blowing on the tubing there.
Good luck [img]smile.gif[/img] ,
Ken K

[Hamfisted]

What Ken said.

And for your fuel quantity problem: Did it work before you installed the new gauges? From your test I would say yes your fuel sender is bad. I recommend the Centroid electronic fuel senders rather than the old fashion float/resistor type that come in most boats from the factory. With the Centroid theres nothing to wear out and they are fully adjustable for more accurate quantity readings. Here's a link: http://www.centroidproducts.com/tableofc.htm . Just remove your existing sender and measure the depth of the tank through the hole, and order a Centroid in that depth range. Then you just trim to the exact depth, minus a little to avoid bottoming it out in the tank, then calibrate it. Its pretty easy.


Mike

[tsmith]

Due to time and expense constraints I bought the old fashioned type fuel sender. The packaging says the ohms goes from 30 to 240 ohms. I remember reading in the manual about setting the switches on the back of the gauge correctly. Is this one of the adjustments? Is there a write-up of what all the switch settings are on back of the speedometer?