Now, before I ask this question, remember I' am a 60 year old retired car salesman,(39 years) and my expertise was selling em' not working on em'. Anyway. How hard is it to install a tach? And wouldn't it be in my best interest to have one? Thanks, Tmikewww
most tachometers will come with installation instructions. on an engine with a distributor and coil it's really easy and straight forward. pick a spot to mount it black wire to ground red wire to a keyed hot white wire to the headlight switch green wire to the negative side of the coil (the same place your points plug into it) rev the engine and watch it move!!
I actually just did this on my Subaru, very easy. The wire that goes to the Tach, in my case green, just taps into the yellow wire coming off the connector that plugs into the distributor. Then like Milt said above, power and ground, then your done!
Here's how I did mine, also a picture of what wire I tapped into. Tach is a Sunpro Mini, got it from Advance auto (also called parts america, Kragen, checker auto) for $30.
Sambars are distributor & coil systems. Possible coil location varies on if it's N/A carb or S/C FI. My coil on '91 SC is right above rear engine access hatch inches away from distributor, this is where I tapped into for my tach signal.
On S/C there is a ECU mounted behind the drivers seat and it has quite a big grommit were the wiring harness enters through the cabin floor. From there I went under the carpet and up under the dash.
Okay, I got the tach installed, but have just one stupid question - for some reason it shows an idle speed that is about twice what I think the little engine is turning.... 3,000 RPM at idle is way way way off. I never bothered to hook up the white(light) wire - figure I really didn't need it -do ya think that is some how the cause? Nothing like spending an afternoon working on something -then it not working!!!!!!!!!!
Easy now. Did you set the switch for the # of cylinders i.e. 4-6-8. Most tachs have this feature and it's usually on the back, sometimes hidden under a plug Not saying that yours does but worth a looky loo
lucky, is it always 3x what it should be? or is it just goofy at idle? rev it up, if it goes to 15,000 rpm you probably have selected the wrong amount of cylinders like tripper said. but if it's just goofy at idle you may have a bad tach.
Yeah, I set it to 4 Cyl - it's not always way,way off but I took it for a ride and at 60 KM/H I was doing 8,000 RPM, in 5th gear - at idle is shows about 3k and by my best guess I would say 1200-1500 tops!
okay, it's set at 4 cyl - I thought something was wrong when at 60 KM/H I was showing 8,000 RPM in 5th gear, and an idle of 3,000~ kinda off right?
Aaaarrrg... Hey - Still need help, Here are the facts as I know them- - I have looked at both pictures on the board that show where you attach the wire to the "yellow" wire by the coil- the small problem that I have is that my connector, the one in all the pictures only has ONE wire, it's yellow but in all the pictures that I see online there is both a yellow and a green wire - I also tried to wire it to the wire coming directly from the coil, still have the same problem with the RPM's Any more ideas?
Don't forget from S/C to NA you will have differences in wiring. If I remember I have three wires - yellow, yellow c/w stripe & green so if yours only has yellow then that's ok as it's the right wire. At this point I might be thinking that the tach is faulty. Just for fun could you try turning the 4,6,8 switch to something other than 4 to see if maybe it's labelled wrong. From what you have told us everything should be working ok.
you may have just solved it.... I just switched it to 6 then 8, it dropped the RPM's to what I think correct, I just need a shop to tell me what it is really turning so I can figure out if I should leave it at 6 or 8.... I guess it is a bad tach, or something like that.......
Lucky dog, what year is your truck? I have a NA engine with a tach, so I could tell you what my rpm's are running.
not yet solved.... I spoke too early, Last night I thought I had this solved, but after going for a canoe ride this AM I realize that the RPM's are still off...... The truck is a 1991, I think I may just have a bad tach, I really don;t know what to do!>!>!>! Everytime I try to make something a bit better, I end up in a whole mess:frustration:
Does anyone know which wire is the signal wire from the distributor's VR sensor? For my Megasquirt installation, I need to get the VR signal to the ECU, and it can't be just reading the coil, as the coil will be controlled by MS. Is it just the yellow wire coming from the distributor? Thanks
Well, well, well. After monkeying around with the truck for a little while, I've come to the conclusion that the yellow wire (thin one) entering the negative side of the coil is the sense wire from the variable reluctor. Just in case anyone is looking for that info