Ok I have a weird tach issue. I have had autometer gauges in my car for 7 years know and my tach has had a jumping/needle problem for about a year. When crusing it is fine just jumps a little at 3000 above depending on how fast I am going. But when I get on it and the rpms hit 6000 which is my redline the needle will go to zero or just be erratic until i get back to cruise speed. It its normal to about 60-70 mph, but anything after that is when it becomes erratic. Could my Accel HEI Super Coil be going or the tach. Checked all the wiring the ground is fine and so are the other wires.
Silver00V6
Sorry.......if you buy something for a test with the intention of takeing it back when you're finished.....*****************! Why is that fair to me when I purchase, what I assume is a new, never used product?
Dude people return dead plants to home depot. If you can get one to borrow i dont see why it would be a problem. He'd use it for 5 minutes and if he decides he doesnt want to keep it as a backup (which it what i do) then he can return it u harmed. Have you never returned anything i. Your entire life? Same thing man.
Yes I have returned things that didn't fit. But IMO it's wrong to purchase something, knowing that you are going to use it and return it......... No wonder kids these days have no respect for anything
Like I said, thats not what I do personally since I like to keep and extra of most things as backup or for testing but for some people who not as well off money wise thry may need to return it.
Testing
We do not advocate purchasing parts for testing, only to return them. Sometimes they get destroyed, like when they are hooked up backwards and burn out, then the next poor guy who buys it cant figure out why it wont work.
No sir we advocate PROPER TESTING here, as much as possible.
If one would listen more than talk , one may learn something about testing, then one may actually become SMARTER than he was.
NOW to answer the Original posters question:
Check over all your connections.
Try hooking the up on another car to see if that has any effect.
My experience has been tachs do go bad.
They can cause a running (driveability) problem at times , but not allways.
If you have a dwell meter, it will have a tach in it. Run that to determine if the issue is your tach.
The only other way I can think of is to use an oscilliscope ( like a sun tune up machine) that would display an ignition pattern, so you can determine if the distributor is the cause, or the MSD unit.
Another point I would like to make , is ... circuit boards take on quite a bit of vibration and at times heat. it tends to cause solder joints to get soft at times during operation, and with added vibration the joint can seperate from the leads of electrical components on the circuit board.
That being said, I routinely repair boards, instrument clusters , climate control panels...etc that have solder joints that become stressed, or non functioning. That may be the case with your tach.
If o are familiar with soldering, you can try to repair it yourself.
Not sure what kind of tach you have , but lots of guys like the ones they have, especially the vintage SUN tachs, and dont want a new one.
Also EOD Guy may have a few suggestions,I would follow what he has to offer as well.
We do not advocate purchasing parts for testing, only to return them. Sometimes they get destroyed, like when they are hooked up backwards and burn out, then the next poor guy who buys it cant figure out why it wont work.
No sir we advocate PROPER TESTING here, as much as possible.
If one would listen more than talk , one may learn something about testing, then one may actually become SMARTER than he was.
NOW to answer the Original posters question:
Check over all your connections.
Try hooking the up on another car to see if that has any effect.
My experience has been tachs do go bad.
They can cause a running (driveability) problem at times , but not allways.
If you have a dwell meter, it will have a tach in it. Run that to determine if the issue is your tach.
The only other way I can think of is to use an oscilliscope ( like a sun tune up machine) that would display an ignition pattern, so you can determine if the distributor is the cause, or the MSD unit.
Another point I would like to make , is ... circuit boards take on quite a bit of vibration and at times heat. it tends to cause solder joints to get soft at times during operation, and with added vibration the joint can seperate from the leads of electrical components on the circuit board.
That being said, I routinely repair boards, instrument clusters , climate control panels...etc that have solder joints that become stressed, or non functioning. That may be the case with your tach.
If o are familiar with soldering, you can try to repair it yourself.
Not sure what kind of tach you have , but lots of guys like the ones they have, especially the vintage SUN tachs, and dont want a new one.
Also EOD Guy may have a few suggestions,I would follow what he has to offer as well.
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