I am chasing a new problem and looking for some advice. After I replaced the original mechanical pump with a reproduction pump. I had an issue with the rebuilt Q-jet leaking gas onto the manifold. I get gas on the left and right side of the manifold. I tinkered for a bit and thought my rebuild was bad. I purchased a rebuilt Q-jet from Eckler’s, installed it and have the same issue. As I was troubleshooting that I discovered that there is a pin hole in the stainless steel line near the intake on the carb which may be unrelated. Any thought on what could be causing the carb issue?

 

You dont state where either one of the two carburetors are leaking.
Did you check if the new pump is supplying too much pressure, over 7 is too much.

 

that would be my guess as well

 

I've had a similar issue before, carb leaked around the base gasket on both sides.....turns out somebody plugged the vent tube from the gas tank. Just one thing you can verify, now that you have good fuel pressure, it's possible the tank is not venting properly and the pressure of the fuel system is finding the easiest way out! Just a thought.

 

I am seeing gas around the accelerator pump and also on the manifold round the front of the carb on both sides. I am not sure if the carb is leaking around the base (new gasket) or if it is the result of the pin hole leak in the stainless steel line running between the fuel pump and the carb inlet. I have not tested the pressure but will do that as soon as I figure out how. I know I need to replace the line with the pinhole but was thinking of using a rubber fuel line while troubleshooting the issue.

 

That is a good thought. I replaced the tank, sending unit, hoses and fuel separator. My understanding is that this is a closed system and the tank itself is not vented but I could be wrong on that. I assume I could test that by loosening the lid on the gas tank, would that work?

 

It should! I would cut a 1 inch piece of 3/8 fuel line the long way, so it's split the long way, then put it around your metal fuel line so the split is on the opposite side of the pin hole, then open a hose clamp all the way and put that around the rubber fuel line right around exactly where the pin hole is and tighten it up (this is for testing only). I would think this should seal the pin hole, with the gas cap still tightened, start it up and let it run and and see what happens (also, for good measure, snug up your carb bolts again and the screws holding carb together). If you still get a leak, wipe it all down so it's dry again and take the gas cap off....now run it again! Most C3'S have a non-vented gas cap and there is a "T" fitting on the driver's side of the top of the gas tank that connects to the Hardline running the length of the vehicle to the charcoal canister hidden behind the front driver's tire behind the the fender, this is how it vents!

 

I was suggesting the "patch" fix to the hard fuel line so you don't have to disturb anything else. When you take your fuel cap off do you feel/hear pressure releasing? When you locate your charcoal canister make sure all hoses are hooked up, if this is indeed your problem a temporary fix would be to just buy a vented fuel cap or don't tighten your existing one all the way! Definitely get a new fuel-pump to carb hardline ordered and replace it.

 

Good thought on the "patch", I had not thought of that but will definitely try it out. I have ordered the new line and will get it replaced when it gets here. I will try out your suggestion early this week as soon as I have a chance. I appreciate the suggestion!

 

No problem, can't help myself, but don't forget to snug up the screws on top of the carb down inside the bowls or between the primaries and secondaries.... can't get an exact mental picture right now but you'll see them! Please post what you figure out, have a great day!

 

Yes, it's a closed fuel system but you have to ensure the fuel EVAP system is installed and operating. The canister is just ahead of the driver side fender louver. Access it by removing the closeout panel behind the driver front wheel. There's a short rubber hose going from the center of the tank to the hard fuel line on the frame. Another hose leads from the carb bow (front of the carburetor) to one of the two inlet connectors at each side of the center. A third hose leads to a "T" in the PCV system on the driver side. A small rubber control hose leads from the passenger side of the carb to a tee where it branches to attach to the two side fittings on the canister. These operate a valve (the carb bowl valve closes with vacuum; the PCV system (purge) valve opens with vacuum.

The hose leading down from the carb bowl vent to the canister takes a real beating--they turn into something like bubblegum over time and will literally stick closed (permanently) if pinched. The line must also lead smoothly downhill with no dips for liquid fuel to collect.

The charcoal inside lasts a long time but isn't eternal You can replace it with charcoal from an aquarium/pet store. It's easy to check the operation of the valves with a hand vacuum pump. Like all vacuum valves/switches they're extremely long lasting.

 

I tried wrapping the fuel line with 3/8 rubber gas line as suggested and clamped it off to cover the pinhole for testing. I also snugged up the screws and found a vacuum port that was not closed off that did not exist on my old carb and capped that. I tried it with the gas cap on and off to rule out some sort of pressure from improper venting. Idle was better but the carb was still filling with gas an leaking from the top when I stepped on the gas. My thought it maybe the new fuel pump has too much pressure and I was thinking I would test that by getting an inline fuel regulator to ensure pressure and installing it after the pump and before the carb. For testing, since I have to replace the hard line, I was going to cut it and use 3/8 rubber fuel line clamped off at the regulator and hard line. If it solves the issue, I will replace the rubber lines with hard lines. Thoughts?

The problem presented after the fuel pump was replaced and I am getting the same flooding/leaking on two different carburetors. This was not an issue prior to replacing the pump.

 

what is the manufacturer and part number of the new pump?

 

I purchased it from Ecklers: https://www.ecklerscorvette.com/corv...Product_Viewed

 

The link doesnt work for me.
Did you buy the AC-Delco pump?
Is the fuel return line hooked up to the pump?
If you bought the Holley pump you need a pressure regulator.

 

I did purchase the AC-Delco pump ( 970-1974 Corvette AC Delco Fuel Pump For Cars With Rochester Carburetor And 454ci Engine). The return line is hooked up to the pump. I had it installed by a mechanic.

 

Since the Quadrajet is rebuilt and typically rebuilds are not done correctly, you may want to ask your mechanic to check the float level. A good setting would be 1/4".

 

I will have the new one and the one that pulled off checked. The old one was working and the car was running well before the fuel pump was replaced, that it what keeps throwing me off. Thanks again for the suggestions and your help, much appreciated.

 

Why don't you just check the fuel pressure at the carb inlet..? Should be above 4 and below 7. Chances are also good that your "rebuilt" carb from Ecklers is a complete POS - I've never seen a good carb from those guys. It's likely hacked pretty bad... e-mail me for info about those commercially "rebuilt" carbs.

Lars
V8FastCars@msn.com

 

Thanks Lars, email is on the way! I appreciate the help.