SBF - 289. Rubber line from tank - Steel line along frame - rubber to pump - rubber to carb. Vented tank - [ not blocked ] Fuel line is not near any exhaust or manifold. Once warm i get sporadic bubbles in the filter. The engine does not stutter, it will "drop" a very little at idle, but will not die. I did buy one of those $10 glass filters that break, im gonna replace that first. Is this vapor lock ? , if it was i would figure the car would start to run really rough. Could the fuel pump be on its way out ? if so i thought it would be also running rough Thanks L
Might be that POS glass filter sucking air some air in the filter is normal also if its running fine, than i wouldnt worry about it. Id still change that filter
That's the problem , once hot , it will stutter in traffic to point of being stressful . I'm pretty sure its vapor lock , gonna look into running a return line L
You can run a temporary gas can with a new hose from the suction side of the pump and see if you still get bubbles. It sounds like air leaking in on the suction side. Could be the sock on the p/u is plugged. I'd bypass the stock tank for a test ride and work from there.
Replaced the filter, put a new pump on there. Took of gas cap, tightened all fittings, . . . . . still got the bubbles, definitely gas evaporating , also check the steel line running down the frame, it is not near any heat L
--------------- A portion of the rubber hose might be going porous from age. If the hose is on the suction side of the fuel pump, air will seep in - but fuel might still not seep out. Mart3406 ==================
Does it still have bubbles in the filter if the tank is full? If not the pickup tube in the tank is cracked or has a hole in it.
Bubbles (and partially filled filter) are normal. You would have to isolate the line(s) and run a vacuum test to ascertain they are air tight. Vapor lock happens on the suction side of the fuel pump. Fuel percolation is the evaporation of fuel in the carb bowls/inlet line if there is significant heat soak. More common is blend separation (again suction side) as today's gasoline is blended for EFI. Cavitation will also occur in a filter installed on the suction side. As mentioned, you need to verify pressure and volume delivery.
Good advice right here. If you are looking to throw money at a problem that isnt there feel free to send me some. The bubbles are normal....
I also agree with the vacuum test. Pull the line off the tank...plug it....then hook up a vac pump....bet you have a leak....could be a pin hole in the metal line....especially if it's old and rusty.
And if ya got any left after throwing some KJSR's way .....I'll take some...ditto on the normal for bubbles
The bubbles are normal as a result of a suction type mechanical fuel pump. A properly installed and rated electric pump will pressurize the system and alleviate most problems with modern fuel. You can take it a step further with a regulated return line with either type pump.
Perfectly normal... Every see through filter I've had on carb'd engines , cars and bikes, has had air in the filter. Probably because they are vented. You will not be able to eliminate them.
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