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I apologize if this topic is already posted, but I haven't seen anything quite like it so I thought I'd ask. I just purchased an 80 coupe that I know very little about. I got it from a dealer who got it from an insurance company who recovered it after it was stolen. It appears to be the original block with aftermarket intake and distributor. My first issue is while the speedometer, gas gauge, and battery gauge all work, the tachometer, oil pressure, and temperature gauges do not. Is the fact that all three dead gauges come from the engine mean the causes might be related? I believe that all the gauges use the same fuse, so I don't think that's the issue. Is there something in particular I should be look for? Thanks for the assistance.
Ok, I took a couple more pictures. What is the yellow sensor coming out of the rear of the intake manifold between the air cleaner and the distributor? It also appears that the pcv valve has been plugged. Does this have any performance ramifications?
Good choice of car! 1980 is the best year of Corvette.
The gauge issue could be as simple as a bent tab on the flexible printed circuit board behind the gauges. It's worth taking a look. It could also be a bad ground. The Willcox Corvette website has some great how-to pages on diagnosing specific gauge issues, so you'll be better prepared for what to look for. Now is a good time to pick up a Shop Manual and Vehicle Assembly Manual for your car, too. Repros are available from all the Corvette vendors, and even from RockAuto.
I think the yellow things are just caps to block unused ports from an intake manifold vacuum Tee. In my 80, I just have an "L" in that place, a single right-angle vacuum port.
You'll want your PCV back. In fact, the way it is connected, your gas vapor recovery tank may not work. Do you also have some gas fumes?
I apologize if this topic is already posted, but I haven't seen anything quite like it so I thought I'd ask. I just purchased an 80 coupe that I know very little about. I got it from a dealer who got it from an insurance company who recovered it after it was stolen. It appears to be the original block with aftermarket intake and distributor. My first issue is while the speedometer, gas gauge, and battery gauge all work, the tachometer, oil pressure, and temperature gauges do not. Is the fact that all three dead gauges come from the engine mean the causes might be related? I believe that all the gauges use the same fuse, so I don't think that's the issue. Is there something in particular I should be look for? Thanks for the assistance.
yeah... go to my tech page... enter your year and search gauge.... there are videos and other helpful tips on how to diagnosis gauge issues.... One of the main things I preach is to let the gauge tell you what the issue is. So go read the stuff and you'll probably find out your issue.
Thank you for the responses. Bikespace, if I understand you correctly, the PCV connects to the gas vapor recovery tank? Is that the line that runs down the driver's side of the car? I just had a roll bar installed and in cutting away the body on both sides I noticed three gas lines, two on the passenger side and one of the driver's. Here are a couple of pictures of the exterior. It's in pretty good shape but the paint is faded and needs a redo.
My 80 is missing that plastic Y, so it is connected differently, but in my wife's 79, the PCV valve and the large hose to the gas vapor recovery tank connect to that Y, which then connects to a large port on the carb. I believe there is a second, smaller vacuum hose "signal" (ported vacuum) that activates a valve inside the recovery tank, but the PCV sucks fumes from the crankcase whenever the engine is running.
It looks like you'll have a lot of fun with that car. You probably want to buy some new tires before you take it on the track, though.
EDIT: It looks like the large hose is also connected to the vapor tank and the carb (like mine), and perhaps the signal line is connected to the Y? Is there a second port on your carb to connect the PCV? Your best bet is likely to find a vacuum diagram for your car (1980 L48).
Last edited by Bikespace; Mar 2, 2019 at 07:17 PM.
1980 gauge question
