20-01-2018, 11:14 AM
The fuel pump has a lever inside the engine that is operated by an extra cam on the camshaft. The lever moves the pump diaphragm to push fuel through the pump.
The priming lever on the outside also operates on the diaphragm but if the engine stops so that the pump cam is on the lever then the diaphragm is pushed up and the priming lever can't operate and does nothing. In this state the lever will be quite slack.
Turning the engine a turn or so on the starting handle will release the internal lever and the priming lever will operate and you can feel it doing more work.
The priming lever on the outside also operates on the diaphragm but if the engine stops so that the pump cam is on the lever then the diaphragm is pushed up and the priming lever can't operate and does nothing. In this state the lever will be quite slack.
Turning the engine a turn or so on the starting handle will release the internal lever and the priming lever will operate and you can feel it doing more work.
Jim