musashi28

So I have a 1973 Stingray that has been sitting for the better part of ten years until a few months ago.

My big issue is when starting the car cold. I have to crank it quite a bit before it will even try to fire. After pumping the gas pedal quite a bit, crank, pump, crank, and on and on the car finally starts to fire(after a minute or more) but is a beast to get going at first. You could have driven the car the day before and it still does this. It just seems to me that the fuel is draining back to the tank or something which is why cranking it for a while finally gets fuel to the carburetor but I have been spoiled by fuel injection for years now and am knocking the rust of two decades off my mechanic skills so...

The other issue is the off-idle performance which may be related as below 2000 RPM the engine does not want to take the fuel but is more than happy get get up and go if I just stomp on it.

Parts replaced
- New fuel tank
- Fuel lines flushed
- Rebuild Quadrajet
- New cap, rotor, points and condenser
- New spark plugs(Delco AC10)
- New fuel pump
- New battery(and the list goes on)

Any help is appreciated

lars

The following info is taken from my Q-Jet Tuning Paper, which is available to all Forum members via e-mail request:

Technical Explanation: My Car Is Hard to Start – My Carb Must be Leaking all the Fuel Overnight!

One of the most common complaints on a Q-Jet carb is that the car is hard to start after sitting overnight or for a few days: The engine must be cranked excessively and will finally start after pumping the gas pedal repeatedly. The common diagnosis is that “The carb well plugs are leaking – you need to epoxy the plugs.” Actually, there are several issues that can cause this symptom, and the plugs are seldom to blame – some of these things can be fixed, and others cannot, but there is no one single cause for this problem:

1. The most common cause of Q-Jet start problems, if it occurs after the car has been sitting overnight or longer, is that the fuel standing in the fuel line between the pump and the carb is draining back through the fuel pump checkvalve due to a slight leak in the pump's internal checkvalve. Since the Q-Jet's needle and seat is in the bottom of the float bowl, the fuel draining back through the fuel pump will actually siphon fuel out of the carb's float bowl. To fix this, you need to replace the pump, but not all new pumps have checkvalves that seal completely, thus the problem can persist.

If this is the case, you can first install a checkvalve inlet filter, part number 23052 from NAPA (for the “long” filter, or 23051 for the “short” filter) and see if that cures the problem. If not, you can remove the clip from your needle so that it will drop down into the seat after engine shutdown to seal off the seat from the siphon action.

2. If this does not cure it, you may have a leaky float bowl well plug (either on the primary or secondary side). Before doing any well plug repairs, I strongly recommend that you verify this problem first: If you remove the carb from the engine and set it up on some tall sockets on your workbench, you can fill the float bowl with fuel and easily see if the well plugs are dripping. Leaky well plugs will be readily and immediately visible. It is seldom that a post-’70 Q-Jet will leak from the well plugs. To fix leaky primary well plugs, drill and tap the well plug area for #10-32 screws. Install 10-32 x ¼” Flat Head Socket Cap Screws coated with JBWeld epoxy into the threaded holes – this is the only permanent repair to the leaky plugs. If the leak is on the secondary side, you can install the thick secondary well gasket that is provided in almost all NAPA/Echlin rebuild kits.

3. Many Q-Jets came from the factory with porous castings, resulting in fuel leaks right through the exterior and internal walls of the carb. If this is the case, you need to replace the carb. I have seen many of these, and you can often find the problem by, again, setting the carb up on your workbench, filling the bowl, and observing where the drips are coming from.

4. A bad accel pump will cause hard starting, and bad accel pumps are extremely common with today’s ethanol-additive fuels. After the engine has been running, shut it off, look down the carb, and flick the throttle lever slightly. Verify that you have an immediate pump shot in both primary venturies. The accel pump will often lock up in the pump bore due to the ethanol in the fuel, resulting in an inoperable accel pump – the lever and pump rod will go up and down, but the rubber “cup” can be seized in the pump bore. This will make the car very difficult to cold-start, but can produce satisfactory performance once the engine has started.

5. Verify correct operation and setting of the choke. An inoperable choke will make the car very difficult to start. See the Choke Setup section of this paper.

6. Finally, there is the issue of modern fuel. If you have stopped the drain-back and siphon problem and have verified that you have no leaks, you likely have a problem with the high vapor pressure of modern fuels in the Q-Jet's vented float bowl. The fuel will simply evaporate off its volatile additives (the ethanol), and this will lower the level of the fuel in the bowl just enough to prevent the accel pump bore from being filled. If this is occurring, there is no fix.

Lars
V8FastCars@msn.com

musashi28

Thanks for the update. I see a number of items that can be eliminated since the carburetor was just rebuilt, including the epoxying of the plugs. I hope that the body itself is good but I did find another Qjet sitting in a bucket next to the car...