Erratic tachometer

[TulsaSpider]

One thing has been bothering me and it's my tach. It seemed a bit erratic before but now it's plain looney. Do I have it hooked up correctly for a 78 that originally had points?


neg side:
Black - goes to coil
brown with white dots

+side
black- from condenser
red - to coil
blue with black stripes.

Do I have something wrong here?

[divace73]

Hey Tulsaspider

I have a pdf document (that I think I orignally got from this forum) that explains the upgrade from point to electronic, there is also mention of placing a capacitor IN LINE with the tacho...if you PM me I can send it to you via email as I don't know how to add the pdf,,,

[TulsaSpider]

Well I ordered the capacitor that the manual says I need. I should get it in this week and I will report back!

[manoa matt]

That big audiovox capacitor/condenser is usually on the + side to deal with radio suppression. Try hooking it up to the - side and see if that cures your indecisive tach problems. It won't hurt.

[TulsaSpider]

Tried that with no change.

[manoa matt]

OK, try this one: http://www.mirafiori.com/faq/content/ta ... achfix.htm

Its odd that after installing the later (79-85) stock electronic ignitions in earlier cars some owners experience the tach bounce and others do not.

[TulsaSpider]

Yes I have a capacitor on order. I will report my results!

[BurbankJalopy]

Hello
Just in case the other ideas do not fix your tach, I'll tell you about mine recently. My tach would drop or bounce around erraticaly or shortly after start up. Long story short I figured out the voltage regulator on the alternator was allowing 18+ volts into the system, causing tach problems. I replaced the voltage regulator for an instant cure. I hooked up a voltmeter with engine running to figure out the high voltage problem coincided w/the tach giving me fits.

[TulsaSpider]

OK another goofball goof on my part. I tried the capacitor exactly same values as the instructions said and it died.. Ok well come to find out in trying to find a ignition only hot wire under the dash to run my electric fuel pump off of I had inadvertently piggy packed on the ignition.... neg side of the coil--? anyways I found an alternate power supply and tried that. The tach is working properly now but it seems the system does have to warm up a while for it to behave. I can live with that. I put the capacitor on again to see if it made any difference and it did not so pbbbt... Oh and I took it for a test drive and the power really improved!!! I thought I wasn't getting enough spark!! wohooo! bonehead move but I figured it out! ^_^