1978 corvette
Thread Starter
7th Gear
Joined: Sep 2025
Posts: 7
Likes: 1
1978 corvette
Hello, I’m having a lot of trouble trying to get my 1978 corvette running. I replaced the pump, rubber fuel lines, the hard fuel line going from pump to carb. I also replaced all the spark plugs and tested them. I also pressure tested the fuel pump and it seems to be around 8-9 psi. However, the car won’t start unless I manually pump the accelerator a few times and then the car dies. I also replaced the fuel filter. I would also like to mention I did open up the carburetor to clean it out and replace the gaskets.
1967 Pedal Car Champion
Joined: Mar 2020
Posts: 8,887
Likes: 4,071
From: US-PNW
Pics of the engine from both sides without the air cleaner may help diagnose...
So it fires up but won't stay running, even if you pu the accelerator lever?
What carb do you have?
Has the car ever run while you've owned it?
So it fires up but won't stay running, even if you pu the accelerator lever?
What carb do you have?
Has the car ever run while you've owned it?
Thread Starter
7th Gear
Joined: Sep 2025
Posts: 7
Likes: 1
Drifting
Joined: Jun 2025
Posts: 1,570
Likes: 554
Suggest siphon all of it out, isolate it, and start over with all fresh non-ethanol.
Once all old cat pee is isolated, you might draw from it, only a gallon at a time and into your DD's nearly full tank.
Le Mans Master
Joined: Sep 2002
Posts: 5,228
Likes: 895
From: Myrtle Beach SC
Dunno if that's your root problem, but that ol' cat pee will continue to cause problems; and will only get worse.
Suggest siphon all of it out, isolate it, and start over with all fresh non-ethanol.
Once all old cat pee is isolated, you might draw from it, only a gallon at a time and into your DD's nearly full tank.
Suggest siphon all of it out, isolate it, and start over with all fresh non-ethanol.
Once all old cat pee is isolated, you might draw from it, only a gallon at a time and into your DD's nearly full tank.
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1967 Pedal Car Champion
Joined: Mar 2020
Posts: 8,887
Likes: 4,071
From: US-PNW
Are you familiar with Lars Grimsrud for rebuilding and tuning Quadrajets to new or better? That would probably be the best option because you don't really know what other owners have done to it over the last 50 years.
BTW, there is also a filter in the gas tank -- called a sock. That could be plugged up with gunk too and not allowing full flow. Try retesting the fuel pump for flow volume into a container. You can have high psi but inadequate volume. I don't know the recommended specs for this but know others will chime in or you can look it up.
Safety Car
Joined: May 2001
Posts: 4,720
Likes: 1,625
From: Fairfax Virginia
Getting that old gasoline OUT of that Corvette is the first thing I would worry about doing. As the guys mentioned above the Ethanol will cause the gasoline to go bad in just a couple months. If you didn't put any ethanol treatment in the gas then you are opening yourself up to multitude of problems.
Do Not try and burn the old fuel the way it is, it can gum up your carburetor in a short time. I like to use the fuel pump to assist me in emptying the fuel tank. Just remove the line going forward and divert the gasoline in to some 5 gallon cans. This is the fastest method for getting rid of the problem gas and not hurting the engine in your vehicle
If you try and burn the gas then you will need to put some new gas in to dilute the old stuff. There are fuel additives that help burn older fuel with no issues. One favorite is the famous "Mechanic in a Bottle" (at Home depot) which will rejuvenate old fuel and help you get rid of it without plugging up your carburetor. This works okay for me in most cases and then I use the Ethanol laden fuel and add it to my regular fill ups to use it up. This way we are not throwing away $3 a gallon fuel...
Do Not try and burn the old fuel the way it is, it can gum up your carburetor in a short time. I like to use the fuel pump to assist me in emptying the fuel tank. Just remove the line going forward and divert the gasoline in to some 5 gallon cans. This is the fastest method for getting rid of the problem gas and not hurting the engine in your vehicle
If you try and burn the gas then you will need to put some new gas in to dilute the old stuff. There are fuel additives that help burn older fuel with no issues. One favorite is the famous "Mechanic in a Bottle" (at Home depot) which will rejuvenate old fuel and help you get rid of it without plugging up your carburetor. This works okay for me in most cases and then I use the Ethanol laden fuel and add it to my regular fill ups to use it up. This way we are not throwing away $3 a gallon fuel...