bummer, I got 350 k miles out my BMW's FP. Running an electric pump out of gas will kill 'em fast. When I'm messing around with my spare pump, I run a little MMO through it.

I erroneously thought that some of the fuel pumps worked off pulsed compression, no reason they couldn't, but apparently all used on small gasoline engines operate off pulsed vacuum. Note: If it was a constant vacuum they would not work because the interruption in the vacuum is what makes it pump. From a B&S service manual we learn the following: "The fuel pump will prime at 30.5 cm (12") maximum lift. Fuel pump pressure is 0.1 kg cm/sq (1.5 psi). The pump is operated by pulsed crankcase vacuum." NOTE: "THE FUEL PUMP PRESSURE MUST NOT EXCEED 1.5 PSI." On this particular engine the pulsed vacuum line is connected to the valve cover.

Shucks, I accidentally hit submit . .................................................... Are you quite certain that the gas you are now discovering, was not already in the oil from before you undertook this rebuild? What may be damaged depends on how long the engine "ran" with contaminated and diluted oil. If the engine had been running with gas in the oil before the fuel pump work, I would expect the exhaust would have had a definite blue or blue-white color "smoke" in it. In which case, the most likely components to suffer damage would be the crankshaft rod journal and connecting rod, the piston and cylinder walls might have sustained some "scoring" or galling, but usually, the piston and cylinder of a 4 stroke engine, are "spared" in cases of gasoline contaminated oil in the crankcase. It usually requires that these engines be "run without any oil" before the piston and cylinder walls see damage (of course by that time, the crank and rod is usually "trashed" as well). Consider a 2 stroke engine escapes damage to the piston and cylinder with as little as 1 part oil to 50 parts gasoline. Also consider the the same amount of oil is sufficient to lube the crank main and rod journals in a 2 stroke engine, but ONLY DUE TO the 2 stroke design using ball or roller bearings in those 2 places. Plain bearings in the typical 4 stroke OPE engine will NOT survive long if run with diluted oil. If all the time this engine has actually run with gas in the oil, amounts to a mere 20 to 30 seconds, I believe all you have "suffered" is a solvent washing of the interior surfaces of the engine. Post engine numbers and let's see if we can find some illustrations of that carb. Maybe then we can retrace your steps during reassembly of the pump.

It vents the chamber so that the diaphragm can move freely. Proper service is to blow across the top of the screen to lift out oily residue if needed. Blowing directly into the port can damage the diaphragm.