[mikeboggess]

Pumping gas into crankcase, replaced the crankcase vent. Could the cause be the fuel pump diaphragm? Crankcase had fuel in it before we changed the CC ventand put in fresh oil., after changing the CC vent mower ran very well for 10min then started pumping oil/gas through CC vent, we assume this is because there was too much pressure because of the volume of oil/gas in CC. The bad river boys wanna know.

 

[tomw0]

Diaphragm or needle & seat. Either can allow excess fuel into the crankcase. The latter more generally when things are parked. The former when the engine is running.
You can test by applying vacuum to the 'crankcase' port on the pump. If it will hold vacuum, then it is not allowing fuel to pass. If it won't it may be punctured or cracked, or stuff may be loose internally. If the body is held together with screws, you may be able to take it apart for inspection. I would expect about any of the vacuum pumps would fill the bill for replacement. IOW, I don't think the carbs are particular, and they all will produce about the same pressure. In most cases the gpm is insignificant. It just needs to 'get it there' because of physical height difference between tank outlet and carb inlet.
tom

 

[RED-85-Z51]

Probably a bad diaphragm letting fuel leak past it, and down the pulse hose to the crankcase.

 

[mikeboggess]

hank you, followed your advice, rebuilt fuel pump, all new parts, since there had been fuel in oil we changed oil, ran for 5 min., changed oil again. Ran mower for 15 min on low and high speed, no fuel in crankcase and no gushers. Thank you again, the bad river boys wanted to know and now we know.
P.S. We like to fix things but we ain't too good on the computer, we haave trouble understanding the hows and whys of posting and replying, hope this gets to you via MTF or Gmail.