I have an Auto meter sport comp silver tach and I think its crapping out. When I start the car up it will just sit at zero and sometimes jerk a little bit. It will work again sometimes if I give it a gentle slap but most of the time this does not help. After I've been driving for a while at varying RPMs it will start reading properly but stops again just as quick. It will not work at all at continuous RPMs (freeway driving). I don't think the connections are bad, could it be the internal?
bsa

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"If they do not run, Then they will die." - Stonewall Jackson

'87 IROC, 355 TPI,700R4, Trick Flow Heads, Comp Cam, Comp 1.6 Rockers, Lucas 23# injectors, Edelbrock headers, Flowmaster 3'' exhaust, gutted cat,
Mallory coil, Mallory HyFire IV ignition box, Mallory Sidewinder 8mm wires, Autolite platinum plugs, K&N filters, Transgo Performance Shift Kit, Corvette Servo, 2,000 Torque Converter

 

it sounds like you should check the wiring...if it all looks good, return it for a new one !!

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1992 25th anniversary edition Z28 (Black W/Red stripes) 5.7 L98 engine, 3.73 gears,
Aluminum under drive pulley's, Gutted air box, K&N air filters, Air Foil, Bosch platinum spark plugs,
8MM spiral core wires, stage 2 chip, engine oil cooler, soon to have a high flow cat with a 3" flowmaster exhaust and P7000 Perelli Z rated tires all around.
Did I mention the interior is fully loaded!