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Bought another vette , need HELP

Nobody Cares

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Joined
Oct 7, 2006
Messages
421
Location
Higgins Lake , Michigan
Corvette
red 81, orange 74 vert. , 80 claret,69 chevy pu
Bought a 1980 vette the other day, needs work. The Battery light stays on all the time. If i pull the 2 wire plug from the alternater the light goes out. There is power (with test light ) on bothe side of the 2 prong plug at the alternater. Should there be power on both sides ??? The Gauge is reading Approx. 12.8 amps. Question 2: If i plug in the white wire to the Distributor for the TACH filter the engine stalls , the white wire is beside the pink wire that is for the Tach. Can't figure out why when i plug the tach filter wire in the engine will not run or start. ?? I'm stumped .

VETTE80CLARET009.jpg
 

wishuwerehere82

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Sep 6, 2003
Messages
2,314
Location
Rochester, NY
Corvette
Red '82 Coupe,Sebring Silver '98 Coupe
For your Batt. light, maybe this will help.
http://www.corvetteactioncenter.com/forums/showthread.php?t=96692
It could be your rectifier diodes.

As for your tach wire killing the engine, there must be a short somewhere in the line between the connector and the tach. If you short the connector on the distributor, it is shorting the coil, and on the HEI module.
Try using a meter to find out if your filter is shorted to chassis ground somewhere before it goes to the tach.
 

Nobody Cares

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Joined
Oct 7, 2006
Messages
421
Location
Higgins Lake , Michigan
Corvette
red 81, orange 74 vert. , 80 claret,69 chevy pu
Ok Pete, will check that out. I did disconnect (pulled the plug apart ) the white tach filter wire on the right side of the engine Which only left the white wire running from the tach filter the the distributor. Thnx Dave :w






:bar
 

wishuwerehere82

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Joined
Sep 6, 2003
Messages
2,314
Location
Rochester, NY
Corvette
Red '82 Coupe,Sebring Silver '98 Coupe
So you have the short separate wire(pigtail) that comes off the distributor disconnected, but the main white wire connected, and it runs.
So there must be a chassis ground (short) in the wire that goes to the tach.

That's what I figure must be happening.
 

Nobody Cares

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Joined
Oct 7, 2006
Messages
421
Location
Higgins Lake , Michigan
Corvette
red 81, orange 74 vert. , 80 claret,69 chevy pu
No, the pink wire is connected going to the wire harness and it runs, when i plug in the white Tach filter wire in, the car stalls and will not start until i unplug the white wire. Dave :W ;help
 

wishuwerehere82

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Joined
Sep 6, 2003
Messages
2,314
Location
Rochester, NY
Corvette
Red '82 Coupe,Sebring Silver '98 Coupe
OK, got it! Same thing, it's shorting the coil to ground when you plug it in.
The HEI coil has the red(right) wire that is batt. to power the coil, and the white (left)wire comes off the low voltage windings of the coil for tach output.
cap3.jpg


So somewhere in that wire is a short to chassis ground, because when you plug it in it kills the spark.
Put your ohm meter between the unplugged wire and the engine block. If it reads 0 Ohms, you have a short.
 

navy2kcoupe

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Dec 16, 2006
Messages
799
Location
West Central FL and SE Mass.
Corvette
2000 Navy Blue Coupe A4 Z51
Dave, you have a talent for getting extremely good looking rides. That 80 looks just as nice as that 81, and I REALLY like the 81! Good luck getting the wiring problem straightened out.
Andy
 

Nobody Cares

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Joined
Oct 7, 2006
Messages
421
Location
Higgins Lake , Michigan
Corvette
red 81, orange 74 vert. , 80 claret,69 chevy pu
Ok, did some checking.With the tach filter out of the bracket by the intake maniifold the car will start and run . When i put the tach filter back in filter bracket the car stalls and will not run ( also sparks ) when touching the bracket . If i have the filter wire on at the distributor and the filter out of the bracket ( car running ) there is no power at the outgoing side of the filter. If the filter is bad , should that short out the power when grounded ???????????? and stall the engine or let the engine run ???? Dave :W:W:W:W:W
 

wishuwerehere82

Well-known member
Joined
Sep 6, 2003
Messages
2,314
Location
Rochester, NY
Corvette
Red '82 Coupe,Sebring Silver '98 Coupe
Ok, did some checking.With the tach filter out of the bracket by the intake maniifold the car will start and run . When i put the tach filter back in filter bracket the car stalls and will not run ( also sparks ) when touching the bracket . If i have the filter wire on at the distributor and the filter out of the bracket ( car running ) there is no power at the outgoing side of the filter. If the filter is bad , should that short out the power when grounded ???????????? and stall the engine or let the engine run ???? Dave :W:W:W:W:W

The filter is a capacitor that absorbs a charge and discharges at a constant rate.
This keeps your tach needle from wiggling around.
You apparently have an internal short from the input to the case ground. Or possibly the output is shorted up under the dash somewhere.
I'm not sure where to find a replacement for it, but it needs to be replaced in order for the tach to work.
 

Nobody Cares

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Joined
Oct 7, 2006
Messages
421
Location
Higgins Lake , Michigan
Corvette
red 81, orange 74 vert. , 80 claret,69 chevy pu
Wishuwereher82, Thnx for the info. I'll Go to the parts wanted for sale and post a thread . Maybe someone might have a Tach filter for sale. Thnx again . Dave :w
VETTETACHFILTERPART8-03002.jpg




:bar
 

Mr. Chuck

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Joined
Jan 19, 2005
Messages
230
Location
Southern California
Corvette
1981 Two tone silver / dr grey
Bat Light Stays On

Bought a 1980 vette the other day, needs work. The Battery light stays on all the time. If i pull the 2 wire plug from the alternater the light goes out. There is power (with test light ) on bothe side of the 2 prong plug at the alternater. Should there be power on both sides ??? The Gauge is reading Approx. 12.8 amps. Question 2: If i plug in the white wire to the Distributor for the TACH filter the engine stalls , the white wire is beside the pink wire that is for the Tach. Can't figure out why when i plug the tach filter wire in the engine will not run or start. ?? I'm stumped.



VETTE80CLARET009.jpg

Had same problem on my 81, check the Trio-diode in the alternator, The lgiht goes out once the voltages on each leg of the lamp are equal. One leg gets voltage from Trio-diode and other leg get voltage direct from alternator DC output. If one or more of the three diode segments in the trio-diode goes open the voltage from it will never match the direct output of the alternator. The replacement of the trio in the alternator is straight forward, once you get the alternator out and apart; a socket set and little effort and you are done. Use of an ohm meter will confirm a bad trio-diode once you get it out. I picked up a replacement from a local auto parts store, after it came in (1 day special order). I believe the trio-diode is very senstive to voltage surges; The reason they warn against jump starting.
 

Nobody Cares

Well-known member
Joined
Oct 7, 2006
Messages
421
Location
Higgins Lake , Michigan
Corvette
red 81, orange 74 vert. , 80 claret,69 chevy pu
Mr Chuck, Thnx for the info. I replaced the alternator and it took care of the problen. Charging like a champ now. Dave :w
 

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