Tachometer Problem

[Keith J]

Fairly new to the forum - lurked a little while but now have a problem that maybe someone could help with.

Tachometer on my 1999 225 Ficht is acting up - showing idle at 2,000 rpm and pegging the needle with very little throttle input. Tapping lightly on the face of the tach makes it jump all over the place. I measured voltage to the tach as 6.25 volts while idling using a multimeter and the gray and black connector pins.

Does this sound like a bad tach or maybe the rectifier going out? I have no idea how to check to see if it's the rectifier.

Thanks,
Keith

[RUSTY63]

Welcome to the BBC.

Do You know which tach you have, could you post that information?

[Keith J]

I'm not sure about the brand/model of tach. I'll see if I can get it out of the dash when I get home from work today and look for that information. It's the original tach on my 1999 Triton TR21 and it has four red warning lights at the bottom that light up sequentially during system check.

I'll try to find out the tach info and post it this evening.

Thanks,
Keith

[ed396ranger]

Mine started the same thing last night. 2001 225HO Johnson. I have the system check. Tapped the face and it went back to normal. I don't think that tapping it is normal.

[RUSTY63]

Tapping on the tach...and that helping....most times means you have a bad tach.

[ChampioNman]

There were a bunch that were made in the "bad years" that had problems, sorry but they are costly especially if you have the system check tach ! Got one right out of the box that was bad, low oil alarm, bad gauge $250. CM

[Keith J]

I pulled the tach and didn't see anything that identified the brand or model number. I seems to be a system check tach though. I tightened all the wiring connections and started it on the hose - it acted up until I tapped on it and then it did fine. Checked the voltage today and it read 6.75 volts at idle. I checked some old posts and found that it should be 9 volts at idle. I'd hate to drop $250 for a new tach and then find out it was the rectifier.

What years were considered the "bad years"?

Keith

[RUSTY63]

Look in the front through the lens, if you look from the top, I mean standing and at an angle you may see writing in the outside edge, this will be the manufactures name.

On a DI the voltage will be about 6 to 7 volts at idle, On a Carb motor the voltage will be about 9 volts on the gray lead.

[Keith J]

I don't know why that last post repeated. Rusty, I checked the tach again for a manufacturer/brand and still couldn't find anything looking at it from all angles front and back. There are some small splotches of what appears to be black paint overspray on the backside of the unit that may possibly be covering something up.

The tach reads to 8,000 rpm, has white lettering on black background, baby blue on the backside, and has the low oil, check engine, hot, and no oil lights on the bottom of the tach face.

Since the voltage reads within normal limits I suppose its a safe bet that the tach is bad - its still giving wacky readings even after making sure that all the connections are tight.

I appreciate the input and help with this

[RUSTY63]

I would say the tach is bad, would be nice if you could borrow one the make sure.

That sounds like a Ferria or Teleflex guage, do you have a picture you could email me?

[Keith J]

It would be nice to borrow one, but I don't know anybody who stocks anything like that around here. It would probably have to be ordered.

I'll try to borrow a digital camera from my neighbor and send a picture of the tach to you. I have one of those hospital jobs where I'm on call seemingly all the time and my turn is coming up, so it will probably take me a couple of days to get it to you.

Thanks Rusty