Problems in the fuel system are generally of two different types: fuel pump troubles and carburetor troubles.
Following are some of the problems and possible causes within the mechanically operated diaphragm fuel pump:
- Pump leaking at joining faces and losing fuel.
- Screws insufficiently tightened.
- Torn fuel pump diaphragm.
- Diaphragm leaking at rivets and losing fuel.
- Diaphragm is damaged and must be replaced.
- Diaphragm material leaky.
- Diaphragm material is damaged by solvent substance in fuel, and must be replaced.
- Excessive pump stroke overstraining diaphragm.
- Pump not installed correctly; gasket too thin.
- Pump pressure low
- Pump incorrectly installed; gasket too thick.
- Spring pressure low.
- Pump pressure excessive; float needle valve forced down.
- Pump installed incorrectly; gasket too thin.
- Spring pressure excessive.
- Fuel pump inoperative or insufficient fuel delivery.
- Valves leaky or sticking; top half of pump must be renewed.