Hi Guys,

I have a 1980 C3 with 17k miles on it. Everything is cherry so I hesitate to start ripping into the dash or anywhere else to start troubleshooting. The car looks brand new exterior and interior, and everything on a car that's 45 years old is bound to be old and brittle, so I really don't want to tear into it unless I absolutely have to. I am the second owner of this car. My uncle gave it to me back in 1996 and I've always taken care of it, kept it in a garage, etc. The only thing I've ever done to the thing was change out all the suspension bushings to poly because all it does it sit, and I changed the catback mufflers because of age.

It was last registered to drive in 2013, and that's probably the last time I started it. After refilling fluids and charging the battery, I immediately encountered two issues:

1. the power antenna motor is constantly running with only the battery connected - ignition off and radio off
2. Turning the ignition to ACC the fuel gauge immediately pins out

I figured I'd try to start it anyway and it will not start - I suspect due to the fault causing one or both of the issues.

Everything checks out under the hood, and underneath the car where the antenna is. It all looks bone stock and factory correct. The forums say there is an anti-theft relay beneath the jack that could be faulty, but I don't see anything beneath the jack, it's just an empty compartment. I do faintly remember there being some funky alarm on the car that the key operated, but I couldn't get it to trigger. The ECM is by the battery.

Hoping there is an easy button here, or at least a solution that doesn't involve me dismantling/possibly breaking anything in the interior. Thanks for any help.

 

I would bet the power antenna has failed, the belt inside is likely the culprit. I would also bet the fuel sending unit on the tank has failed as well. Your dash will thank you for checking those two first.

 

The white plastic drive cable inside the antenna will break due to age. Very common.

The antenna motor will run continuously until you unplug the wire harness .....behind the driver, under the carpet, on top of the drivers side rear wheel well. Just pull the carpet down and find it.

kits are available to rebuild the antenna. Not too difficult. Aftermarket antennas do not work on the same logic so I would not advise you to go that route. Just does not work with the factory radio.

 

Thanks, Guys. I'll order a fuel sending unit and antenna rebuild kit. I am not new to car forums, so I will update this thread as soon as repairs are completed. If the fuel sending unit has failed, this would explain the pegged gauge and the non-start.

 

The pegged gauge could also mean a corroded terminal or broken wire in the circuit (usually at the rear of the car). Check out the 'simple' things, first...before you go spending money on "new" stuff.

 

I hadn't considered that. Definitely worth doing that before purchasing a new sending unit.

 

For the antenna removal no need to pull carpeting up.
Behind the driver side rear speaker or block off panel if no speaker you'll find connectors for both the antenna wires and a connector for the co-ax cable.
Push the rubber grommet out from there and remove the antenna from under the car.
Removing the antenna is easiest to do while laying on your back with the car on the ground. Your reach and arm angle are most comfortable that way.
Lot will say remove the muffler but not necessary.

 

I have an 82 with 11k miles on it that is nearly 99% stock (tires) so I can completely understand your reluctance to start dismantling things. Time is the fire we all burn in including our Corvettes so issues will need to be addressed regardless of the miles driven or not driven. I personally would not let any of my vehicles sit for 12 years without starting/driving it. I periodically start my 82 and lightly drive it to keep the drivetrain lubed. I also periodically operate the AC, windows, radio, hatch, seats, wipers, etc .because I believe this prevents deterioration from 100% nonuse. It is my understanding oil deteriorates over time as well and I change mine once a year. Late model Corvettes engine oil life monitors will go to zero after 1 year even with zero miles driven.

Speaking of tires I would guess yours are well over 10 years old and I would definitely replace them.

It seems you appreciate the treasure you have.

 

Hey Guys,

Thanks for all the responses. The car is garaged 100 miles away from me, so walking out to the car and checking things isn't an option. The car is carburated, so I guess the fuel sending unit, failed or not, wouldn't prevent it from starting. Also, can't find the antenna circuit in the attached diagram. Why would the antenna motor run with just the battery connected? Is this normal operation? Assuming it's a closed circuit unless the antenna cable is intact?

 

Logically....the antenna needs to retract even after you take the key out and walk away so.....it's hot until the retract limit switch in the antenna is triggered. If the white drive cable breaks, the antenna never retracts....the limit switch is never activated....and the motor runs on and on unless you find a way to cut the power...

This a a very well known failure mode. Been here, done that.

 

Copy that, it makes sense in a backwards, 1970s kind of way.

I guess I'll need to order an HEI dizzy on top of the fuel sending unit for my next trip out. Don't know what else could keep a simple thing with such a low amount of miles from starting. It's got juice in all the right places!

 

I winter store a lot of cars for people. So many times they will crank and crank and not start after setting for months.
Even tho you see gas in the carb.
I will simply pour a bit of gas directly into the carb and starts right up. Maybe half a small(4oz)Dixie cup.

As for the antenna that's exactly what's happening, broken cable that pushes it up and down preventing the stops from resetting.
Pretty sure 80s ant.relay is in the jack compartment. Unplug green/gray/white connector.

 

Papillon _1980

Brake lights work?

Gas gauge change when stepping on brake pedal?

They share a common ground at car's rear.

Mapman

 

I'll need to get back to the car to confirm. That's good to know. Thank You. Will respond asap.

 

You're right in taking caution when approaching troubleshooting with such a nice 1980. Couple of thoughts and suggestions follow.

Can't recall if it was on this forum or the NCRS tech board, but the writer explained the challenge of getting fuel to carburated vehicles and described a fix. I saved it but will have to look around for it. But Kaps describes the immediate fix. Here's a dated article that provides background on the sending unit and describes how to get it working again. I did see where you ordered a replacement. Your replacement procedure will be the same. I followed this fix some 20 years ago and my 78 still registers fuel tank level. In fact...the LOW FUEL light came on recently.

https://www.hunt4cleanair.net/Articl...nitRestore.pdf