Gaffrig Tach misread
 

My Gaffrig tach (do not know the model number) is reading high by about 3-400 rpm for some reason. At idle and also at speed. Any ideas??

It is in a 98 boat.

Thanks, Allan:)

Check your secondary ignition (wires, cap, rotor, plugs). Worn out parts can cause high readings.
Gary

My guess is the tach is set up for the wrong engine. If yours is like mine there are dip swiches on the back. You will need to call Gaffrig tech & they can send you the sheet on the proper switch setup. When I got mine the sheet was wrong but that was 3 years ago.

Turbo, ran it last year without any issues, thanks for the idea though, I will check it out.

Gary, good idea, I have new plugs....I will pull the cap and see what lies beneith. Probably should be done anyhow....

Thanks guys....any other ideas anyone??

Seeya, Allan:)

I would still check the dip switches, Could be that one was not all the way set & bouncing in boat cased it to move.

BTW, if you have 1 plug wire pulled off it will read about that high.
I've also had tachs that just went bad and gave the wrong rpm.
Gary

Try calling Gaffrig and see if they will warranty it for you. i know it is out of warranty but it's worth the call.

My gaffrigs are a little over 1 year old. Both worked fine last year. This year, the starboard tach started acting up. It is very erratic when I first start the engines. A little rev will send it to 5000rpm. By the time I am out of the marina it settles some, but is still bouncing 200rpm around actual. After running 10 or 15 minutes it acts normal again.

I called Nisonger (place I bought gages) they said it sounded like a ground wire or corrosion. I think they are trying to get me off the free replacement path, but I will do the wiggle test anyway. I may also try switching the 2 tachs to see if the problem follows.

Let me know what you find Allan,

Dave :cool:

Dave, I'll let you know, but something is up on the entire boat. I also started to have problems getting spark. Not sure what the deal is here. I ran the batteries (old batteries, ordering new ones anyway) dead trying to get it to fire. NOthing. Then I slapped a jumper cable on from another boat and it fired right up. Not sure what is going on, but I definitely have some sort of ignition glitch I need to track down. I am going to start by putting two fresh Optima blue tops in the boat and see what that cures. It needs new batteries anyway. My bet is that the lack of fire and the tack misread are related...may as well start with the most simple thing. I'll let you know what I come up with. It ran great on the hose....not on the lake!! MSD 6AL, hope it did not take a dump on me......

Thanks guys, I'll check into all these things this weekend.

Allan:)

Gary.....it ran clean once it fired up, just was afraid to shut it off and the tach was reading high. I'll just have to go thru and check out the entire system. Thanks for the help....