No Gas to the Carb; Glad I made it Home!

[Cobra 29]

I need to understand what happened. I was driving today in 95 degree weather, engine temp was around 180, have 1/2 tank of gas. Nearing home the engine sputtered and stop dead 50 feet from the drive way (of course it is uphill to the drive). On the third or fourth restart the engine ran briefly to get us home.

Upon inspection there was little or no gas in the front bowl. The electric gas pump ran continuously. I disconnected the fuel line to the carb to test the gas flow. At first nothing then the pump primed itself and gas began to flow. I reconnected the fuel line and the engine started with no problems. No time for a test drive to throughly test.

What happened? Is this vapor lock? If so, how to I prevent? Many times I take my kids (one at a time) with me on drives. I need reliability!

[Cobra20646]

This is hard to believe, but I had just about the samething happen to me tonight. My wife and I drive about a half hour to visit our son and his wife. Temps today were mid eighties.
The trip was uneventfull..... normal even.
An hour or so later, we hear a thunder storm approaching, and my son suggests we take his car from the garage and move the cobra into it should it decide to rain.
Cobra starts right up and I pull from the drive way to the street so he can back from the garage. When I'm pulling in, the car acted like I stalled it....... just quit running. Starter motor turning over the engine, but it won't start. I finally use the starter motor to move the car the last ten feet into the garage.
After dinner, we go to the garage to see what the problem is. While stroking the accelerator, I can't see any gas from the accelerator pump. I pull the fuel line and try to blow air into the carb to see if the needle valve is open......... appears that both needle valves are stuck on their seats, as I can't get any air into the carb. Pull the top off the edelbrock and see that both fuel bowls are about bone dry..... but now I can blow air into the fuel intake and see the floats and needle valves doing their job, although one needle valve will stick closed, but a slightly stronger puff of air will open it up.
Next step, turn over the engine and see if any fuel will flow from the mechanical fuel pump. Seems OK, but the pressure seems low, as I can cover the end of the fuel line with my thumb and stop all flow.
We put everything together and fire it up. Runs perfect. My son follows us home to make sure nothing unexpected happens. When I get her in the garage I again pull the fuel line and put my pressure gauge on it........ reads just a tad under 7 pounds, which is normal.
I'm stumped.........
I'm thinking vapor lock now too.
Anyone here explain exactly what vapor lock is and what it affects? Does a vapor (gas) get into the fuel pump and prevent any liquid from being pushed through it?
Under hood temps were quite warm, but water and oil temps were "normal" for my car, 180 and 160, and I've run the car through hot summer days many times before and never experienced anything like this.
- Jim -

[xlr8or]

How low were you on gas?? As gas is consumed from the tank it must be replaced by air. When you start getting low it can create a vacuum in the tank and since the fuel pumps push better than they pull you can get starvation. That is why some gas caps are made to let some air in but not let fuel out.

[Mr.Fixit]

Make sure the electric pump is on. You don't get vapor lock on electric fuel pumps, only mechanical pumps which are bolted to the engine and receive alot of heat soak. Is the pump "self priming" mounted lower than the gas level? If not, it only akes an air bubble to cause the pump to cavitate and not be able to pull fuel into it. You can hear if this is happening, the pump sounds different when there is no load on the impeller. What about your fuel filter. Make sure it's not full of debris. The needle and seat on the carb can stick and prevent fuel delivery. On a holley, just rap the top of the adjustement screw/ nut with your screwdriver handle, that usually works. Gas in the tank above the pickup, fuel pump mounted below fuel level, fuel pump running, no kinked hoses or blocked filters, is there pressure at the fuel line to carb inlet.