dennis wrote:A friend has a Twin II L-Head Briggs and Stratton 18HP engine, model 422435, type 1199-01, code 87112412. The carburetor fuel pump cover has two tiny vent holes that are seeping gasoline. Could this be caused by a hole in the pump diaphragm? Could it be caused by a sticking float or dirt under the inlet needle? To remove the carburetor, I read that you have to remove the intake manifold first (with the carb on it). If the problem is a leaking pump diaphragm, can the diaphragm be replaced by just removing the 3-screw fuel pump cover without removing the intake manifold and carb?
Just some tips from experience:
No need in removing the intake on that Briggs l-head opposed twin engine to remove the carb. You may have to remove the mower's hood for easier access. You will need a 1/4 inch drive socket set, 3/8 socket and extensions to remove the carb bolts. (they are accessible from the bottom of the carb and if they are torx use a 3/8 socket or a torx adapter. Torx is more user friendly.
The 3 screw fuel pump is bad and since you have never been into one you most likely need to remove the carb and go to a clean workbench. You will need a 393397 fuel pump kit. You can look at exploded views of the 3 screw pump so as too get an idea of the layout.
You can use little dab of vaseline to hold the itty bitty springs in place and in the kit sometimes both springs are wound together to look like one spring AND if you put it back on the mower and it's still leaking you did not get the front cover and diaphragm correct. (sometimes the front diaphragm is not user friendly to get in place for a seal at it's very lower edge)
You can try it while on the mower but just be aware that you will most likely have to remove the carb.
Be careful when re-installing the carb, the plastic adapter under the carb has a little locator pin that goes down to help hold and align the adapter. If you break any of the mounting gaskets. just get a piece of cereal box cardboard and make the gasket using the other one as a pattern.
Have patience when re-installing. Once you have done one the next time will be more user friendly.