After running my vehicle and I turn it off, gas floods over into the intake flooding the engine. Won’t start.
- Could be fuel pressure – When the engine if shut off there should be some release of pressure. Make sure you have a vented gas tank. After running open the gas cap. Do you get a rush of air? If so, then you need to vent your gas tank. Some vent through the gas cap itself and some have a separate tube coming up from the gas tank. Make sure the tube is clear. Test your fuel pressure. Should be about 4 lbs or less, but compare with what your motor manual says.
- Your gas may be percolating – The engine gets hot, you turn it off and the gas boils over, or evaporates out of the carburetor. Gas has a lower boiling point these days and especially in hot parts of the year, this may be a challenge. Experiment with different brands of gas. Try Startron ethanol additive in the gas. Make sure fuel lines are away from the manifold. Is your water running at a good temperature. While very hard to find, spacers will sometime help. Do you have a bowl vent on top of the carburetor and is it hooked up to a hose correctly? Check the bowl vent gap. Specifications are in the carburetor kit instruction sheet.
- Some Holley 1920 carburetors have a hot idle compensator. The compensator opens a vent into the main body letting off some pressure when coming to an idle. If the idle compensator is bad the idle will be erratic. To test:
- Remove the air cleaner with engine running.
- Cover the hot idle port. If the idle smooths out there is something wrong with the idle compensator. Check the seal and/or replace.