Bubbles in Sediment bowl ???

Jim Parker Toronto

Jim Parker Toronto

Well-known member
I was at a friends place tonight to sort out some problems. Car will run for 15-20 minutes and then it stops! While searching for a fault, noticed a small stream of bubbles coming from the carb, going back up in into the sediment bowl. Once these cleared, the car could be restarted immediately. We did this several times. I checked the temperature of everything around with a Laser Temperature Gun, and there was nothing over 150 degrees. (Gas line, carb, coil, sediment bowl, intake manifold, rad, and block.) This does not seem hot enough to boil the cheap gas to me. I don't know whats causing this, any help would be greatly appreciated. TIA, Jim
 
Did you check the gas cap vent? Could it be pluged up causing a vacum in the tank and pulling air back up the line?
 
Air leak? Are you sure it was coming back from the carb? Pump and vac is all going the other way.
 
Gasoline boils over a wide temperature range starting around 100 degrees F and going up as the lighter components are boiled off.
 
Not to change the subject (I guess i am kind of) but are all flathead fuel tanks vented?

Did you check the gas cap vent? Could it be pluged up causing a vacum in the tank and pulling air back up the line?

That would make sense if the pressure in the tank is beyond the engine vac and psi of the fuel pump. huh.
 
No, its not old winter gas. Its fresh, but the 87 kind. The sediment bowl is tight, with a new gasket. The vent in the carb bowl will be checked tomorrow!
 
Ah crap, I thought this thread was in the early v8 section. I will cordially shut up now.
 
When the engine went dead, did you pull the fuel line out of the carb and check the flow at that point?
The only other thing I can think of other than vapor lock is if the shut off valve has one of the stand up screens on it and it is cloged.
 
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We tried to pull the line to check the flow, but got bubbles, and then a good flow. The tank was just cleaned and sealed, with a new shut off. Thanks for your ideas.
I feel our problem was all with the cheap gas that was boiling even at that low a temperature. I'll check with my friend later, no answer on the phone yet today, but I feel confident that that was it.
Thanks for all the replies and suggestions, Jim
 
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