Fuel starvation at the carb???

[saltman]

I have good fuel flow to the carb inlet. The motor will start right up... then, after 4-5 seconds, it will slowly die within 3 seconds. I have a reproduction Zenith on it and initially it cranked right up and ran beautifully. Then, I started having the starvation problem, which I blamed the inline filter for. But now, nothing is to prevent fuel flow to the carb. This problem did't happen suddenly, but over time. I need some carb help here.,, now, if you are watching... Thanks! Saltman

[Tom Wesenberg]

If the fuel has good flow into a quart jar, then you need to take the carb apart and clean it. Junk must be plugging the needle and seat, or they are sticking closed, or one of the jets is plugged.

[J Franklin]

Maybe junk in the filter screen in the carb?

[saltman]

Tom,
The car is about to undergo complete restoration next week, thats why I was running it. Unfortunately, the car has been sitting in one place and only cranked occasonally. Would this support your suspicion that the carb is dirty from a rusty/dirty gas tank and things are sticking due to lack of use?

[Ken B]

I had a similar problem years ago. When I initially tested the flow to the carb, I thought it was fine as I only let the gas flow for about a second. After many other tests I went back to the fuel flow to the carb. This time I let the flow continue longer than a second or two. Sure enough, the flow started out great and reduced to a trickle after a few seconds. What I found was a little piece of brass from when the fuel valve core was drilled out was stuck in the core. I dug it out and the problem was solved.

[Gary WA]

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Remove the drain plug bottom of carb 1/2", turn gas on, put can under carb Should have good fuel flow from the carb. If slow plugged!! If it is a zenith as jfranklin states check the carb filter looking at carb right side 5/8" wrench, Gas off.

[MikeK]

Let’s try some simple rough geek math
Brake Specific Fuel Consumption for a normally aspirated gasoline engine is .45 to .55 lbs per hour per horsepower.
Driving W.O.T. with 40 horses is ~20 lbs/hr or 3.33 gallons/hour. That’s 426 fluid ounces/hour.

In 60 seconds, you need a bit less than 8 fluid ounces.
If you have a “hot” banger, 60 hp, that’s 12 fluid ounces in 60 seconds.
I’d probably want at least a 40-50% margin, so 12 oz/min bone stock, 16 oz/min for a hotter motor.

Remember, that’s fuel delivered to the carb bowl, not just through the line. Float valves can be restrictive! To get a true picture, drop the bottom half of the carb and wire the float open only ¼” down. Then put the catch container under it. Why only ¼” down? Simple- if you can’t maintain that fuel bowl level at WOT, the carb will get the lean surge DT’s as you drive.

Clear as mud?

[Fred K-OR]

Did you also check your filter in the gas tank? (If you have one) Some large chunks of rust could be covering the gas tank opening and not letting much gas through. This could be why it starts and quits-gas had filled the carb but did not continue.

[Tom Wesenberg]

You say the car has mostly sat around for some time. This ethanol gas at best is garbage gas when it's fresh, but when it's a few months old it turns to sewage gas.