my 82 vette is my daily driver lately I have been noticing some issues arising.

1) my tach seems to be going, when first starting the car it will drop to zero and stay there every now and then might pop up for a second or two maybe freeze at a position. but after 5 minutes of driving it will start to respond better and once it is responding properly it doesnt stop responding until i turn off the car and then start it up again. Could it be anything other than the tachometer and assuming it is the tach can i get it rebuilt or should i just buy a new one altogether.

2) with all this rain we have been having in pensacola i have noticed my passenger floor board getting wet/soaked. I know it is NOT the heater core because i just replaced it last summer and the wet floorboard only happens when the car is getting rained on (driving or parked). I seem to have noticied it coming from two places one is at the front of the door it seems to be sliding inbetween the door and body and draining into the floorboard not out of the car. the other place is i have seen what seems to be a thin line of steady water (when pouring rain) from the front right corner of the passenger floor pan, is that where the fresh air intake is? Is it common to develop a leak in that area?

3)my fuel gauge freezes after half full and doesnt drop anymore or sometimes freezes at different spots like quarter full, is this the sending unit? Do I need to replace the whole thing?


Thanks!

 

The thing I have to offer, is it sounds like the capacitor is either came loose or going bad. My tach went wacky when I did the top end on the l48. Turned out that the capacitor was loose. Wish I knew more about your leaks or fuel gauge. Good luck with your project.

 

Fuel gauge is probably your sending unit or a ground in the system. Do a search on the forum, there's a good diagnostic process for fuel gauges that I think was put together by Willcox. Sending unit is pretty easy to replace on the later C3s because it is in the top of the tank.

http://www.parts123.com/parts123/yb....Z5Z5Z50000050G

 

silly question maybe but where is the capacitor on my tach and can i diagnose with a voltmeter?



yeah i have replaced the fuel pump before the ease in removing the sending unit is a god send. any insight on tach rain water issue?

 

The capacitor is bolted to the intake manifold. Follow the tach wire out of the distributor and it will lead you to it.

 

1)The tach's have a couple common problem areas. One is the "tach filter", which I believe is mounted on the right rear of the intake manifold, near the distributor. Another problem area is the circuit board, in the tach. I think the Shop Manual has a couple checks you can do, to test the tach. My Shop Manual is in my shop, but I can try to take a look at it in the morning.

2)The windshield frames in 68-82 Corvettes, are notorious for leaking. The factory used a little sealant across the windshield frame header, to seal the area where the outer stainless molding, meets the t-top header molding. With time, the sealant dries up and shrinks, allowing water to get in the frame, and run down the a-pillars, where the water leaks onto the floors. This is why so many 68-82 Corvettes are found with rotted out a-pillars and cowls, as well as rusted floors on 76-82's.

There is also a problem with water getting in through the cowl, in the area on the outer edges of the cowl, that form the plenum, to feed air to the vents. Check under the screens, on the left and the right of the wiper area, for debris and clogged up drains.

3)The issue with fuel gauge, is likely with the sending unit.

 

From what you describe about the tachometer, the board could be taking a hike. We have these on the web site and we also have a ton of diagnostic info there as well. They are an easy fix assuming the analog movement is in good condition. (most are). But this could also be a issue with the tach filter so a quick test is to un-plug the filter and plug the tach wire directly into the distributor and see if the problem goes away.



Tach Board:
http://willcoxcorvette.com/product_i...ducts_id=26787

Tach Tech pictures:
http://willcoxcorvette.com/advanced_...&keywords=tach

Tach Board Installation video:
http://willcoxcorvette.com/advanced_...&keywords=tach

How to remove the tach with easy for repair and other files. (you must click on the document you wish to view). http://willcoxcorvette.com/advanced_...&x=-987&y=-172

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In regards to your question about the water leak. Remove the kick panel from the car and inspect inside the A-pillar. It is smart to do this when you see the water leak coming in. If you see water in the A-pillar then you have a hole in the windshield frame that will need to be repaired…

I did another write up on this and you can find it at this link: http://willcoxcorvette.com/repairand...lp.php?hID=306


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Now to the fuel gauge.. I did another help page in these and you can upload it for free at this link.

Corvette Fuel Gauge and Sending Unit Testing 1977-1982
http://willcoxcorvette.com/repairand...lp.php?hID=277

Another hard call here but here goes.

Pull the ohms wire on the sender and see what the out put reading is on the sender. The scale is 0-90 ohms and it is linear. So when you have a ½ tank the reading should be around 45 ohms.

Next.. ground out the ohms wire and see if the fuel gauge goes to empty with the key on. Next let the ohms wire dangle not touching anything and see if the gauge pegs full. If you have these functions then the dash unit is fine and your problem is either the sending unit or the tank!

The tank has a bladder inside it and when it gets old it can separate from the fuel tank. Fuel in most cases can get behind this bladder or warp age can cause interference between the float on the sender and the bladder. When this happens the lever won’t be able to go to zero.. (personally I think this is probably your issue). If this is your problem the solution is to replace the tank with one that doesn’t have the bladder.

Oh.. I have the senders should this be your problem http://willcoxcorvette.com/product_i...roducts_id=570 129.00

 

thank you gentleman for your help and advice i will look into them this weekend. Wilcox I will probably be making an order through you shortly.

 

 

update,

1) couldnt get the tach to act up when i went to test it, plus my tach barely reaches the tach filter bypass plugin but i can stretch a wire between the two if necessary. I will have to wait for a morning that acts up

2)I put a cup of water down the windshield. it ran to the reat of the pillar and out the outside of the door. no water in the A-pillar. It also ran down the drain inbetween the windshild and fender in the wiper tray that ran out the bottom of the car. no sign of water. it seems maybe its just due to my weather stripping. I am gonna get a hose and apply water to the windshield for a longer time to see if i can find anything

3)although my tank only had what i believe to be about 4 gallons it was reading over 1/4 full on the gauge and about 33 ohms on the ohmeter so im thinking its the sending unit. although when i unplugged the unit the gauge went past full, should it have dropped to empty?

 

The gas tank is only 16 gallons so 4 gallons should get you around 1/4 full. How much over 1/4 is it reading? Unplugging the unit should make the gauge read way past full.

 

tank is 21 gallons...trust me ive gotten up to 22 gallons in there when i had to push it to the station once

 

there are some rubber plugs on the bottom of the floorboards that may have fallen out causing you water leak..........had an 80 many years ago and the floor was wet after driving in the rain, it was getting kicked up from under the car. easy and cheap........if thats the problem