slipbakka

Hello i just install a new aftermarket tach gauge and voltmeter in my 1987 2 door cutlass supreme with a 3.8L V-6 motor.The problem is i hook the tach just like the manual told me hooking the green wire to the negtive side of the distributer.but the tach needle doesn't go pass 2000rpms even when i raise the engine up the needle doent move just stay's a 0 rpms. the tach gauge is a racing summit tach gauge with 0 to 11,000 rpm.also the voltmeter works fine but when i turn on the turn blinkers the volt meter needle bounce up and down with the blinkers.and when i turn the a/c ,radio and headlights on the meter drops from 14 volts to 10 volts.can someone help me im confused?

Oldsguy

Many tachometers have a 4cyl/6cyl/8cyl switch. Sounds like yours is still on 4cyl, check it. As for the voltmeter, where is it connected to? You may have either a poor connection or you may actually have a charging system problem which is what the voltmeter is supposed to do, tell you when your system voltage is low or high.

labrats804

my 87 cutlass has the stock voltmeter and it does the same thing. When I have the turn signal on it will bounce up and down...if the headlights are on as well as the turn signal it will go down to about 10 volts as well. I thought this was normal, but I could be wrong.

slipbakka

Hello oldsguy and labrats804 i have the tach on 6cyl and it does the same thing the needle don't move it just move to 2000rpm even when i raise the engine.and the voltmeter i have the red wire connected to the fuse box were the acc opening is at the fuse box under the dashboard,the orange wire to the contact that always have constant power under the dash,and the black wire connect to a piece of metal behind the radio that i scraped real clean.i hope i didn't waste my money on these gauges

perro

im assuming you have an HEI distributor in your car.
an HEI will only accept an ELECTRONIC tachometer - unsure of what you might have, but an electronic tachometer is all it will be able to use.
there is a terminal on the cap of the HEI that will have the word "TACH" on it. Your wire from the tach should go there. It will take one of these kinds of terminals
http://www.allelectronics.com/images...large/1125.jpg

you should have most likely 4 wires from the tach

1 needs to go to a good ground
1 needs to go to the TACH terminal on your HEI
1 probably goes to switched 12 volts (from your ignition switch)
and 1 will most likely go to your dash lighting so when you turn your headlights on it will also light up

if you have an HEI, and you have the tach wire attached to the terminal marked TACH on the cap, then find out if the tach is electronic



next - your volt meter
im a licensed electrician and i build big fancy buildings, and i understand DC theory, but im not an automotive expert (especially on computer controlled cars), so take this advice for what its worth, and thats not much - im just now getting back into old cars and ive been out of the hobby for a while

your car is a 12 volt system
going of memory, a fully charged battery with the ignition off should give you a reading of somewhere between 12.5 - 12.8 volts - not running.

when your car is running the altenator/generator takes over and produces electricity to charge your battery - with the engine running, the volt meter should read about 14 - 15 volts cause of the altenator. The volt meter should stay around 14-15 VDC until you put the electrical system under load (turning on the lights, wipers, heater, AC, stereo, turn signals, etc. etc.)

if when you have the car running, & you turn on any accesories and the volt meter reading falls below 12 volts, then that means your battery is providing some of the current to feed your accesories. Driving around like this for a while will drain your battery and it might be hard to start your car after you shut it off.

if the voltage is constantly below 14 volts, you need to have it checked and replace whats bad cause your charging system isnt working 100%

if it ever goes above 15 volts, you need to check your voltage regulator


hope this helps a bit

sorry for the long post


Mike