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Carburetors usually don't require as much fuel pressure and fuel injected engines, especially if it's not a tbi. If the fuel pressure isn't knocked down either by changing the fuel pump or at least by installing a regulator, then the too high fuel pump pressure will force the float needle off the seat and flood the engine.
So, let me continue by asking what engine this is, what was the original fuel system and what carb is on there now, what fuel pump/pressure do you have, etc?
Was this the 1976 Volkswagen Truck Transporter 2.0L FI 4cyl? If so, that fuel pressure was 28 PSI. That is way too much for a carburetor. Normally they only require like 7 psi.
When gas enters the carb float bowl and the float rises, then the needle should be forced against it's seat and shut off the flow of gas, so if you have a problem with this, then the foat either has a hole in it if it's metal or could be to heavy if plastic, or the float may need to be adjusted.
Could you then explain what I am not understanding? How did you come to lower that fuel pressure? Did you install a different fuel pump and/or a different regulator or is there an adjustment on that regulator? Nonetheless, if fuel still flows through the fuel pump and the regulator while the engine is off if a mechanical fuel pump or the engine is off and key off if an electrical fuel pump that I agree, that isn't right.
I agree, you should speak to someone who has done the conversion. I'll opt out then, perhaps another expert on here as done one, if so, they might give you an answer. Good luck!
Hello, I understand your concern of the tank gravity feeding. The solution to this is to install an inline fuel cut off solenoid. Just plumb it in before the carb and power it off the + side of the ignition coil. Here's a link to one. You may have to use a smaller nipple depending on your fuel line size.
After the solenoid install an adjustable fuel pressure regulator. Most carbs for these work best at 3psi.
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