6 ms·
This is the first time I've heard of intentionally running a fuel pump backwards and I wonder whether you're right. The fuel pump in modern vehicles is normally
by hathawsh 6y ago
This is the first time I've heard of intentionally running a fuel pump backwards and I wonder whether you're right. The fuel pump in modern vehicles is normally submerged in the fuel tank. My guess is that air drawn in by the pump would just make harmless bubbles; the pump would still be fully lubricated. Does anyone know for sure?
- dkdk8283 6y agoFuel pumps on EFI motors have a supply and return. Return is significantly smaller in diameter and will probably allow the engine to barely run at all. It would probably start and shut off giving the thief the impression the car is junk instead of being disabled.
- spiritplumber 6y agoOh, this thing was made in 1975. The motor is a mopar 440.
- technothrasher 6y agoNot all EFI systems use a return line. Some use a PWM controlled pump, rather than a pressure relief valve, to keep the fuel rail pressure constant and so forego the return line.
- throwaway0a5e 6y agoYou're forgetting the part where the fuel pump is a vane pump and will pump in reverse just very poorly (assuming directional rotor, which most have).
- throwaway189262 6y agoIt's likely old and carbeurated. Running pump in reverse may serve to empty the carbs fuel "bowl". Some cars can run a good while off the bowl. Enough to get a mile maybe.