Hi, Is there a diaphram in a mechanical fuel pump that can go bad & suck oil & make engine smoke? Thnx

 

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Maybe? The only connection into the "oily" part of the engine is the actuator arm that operates the fuel pump, and is operated by the camshaft or crankshaft. Any leaks there generally just leak around the gasket where the fuel pump mounts to the engine. That said, there IS a diaphragm, and it is operated by the actuator arm. The last engine I had with a mechanical fuel pump was a 1973 Ford 302 V8 with a 2 barrel carburetor, and I got rid of that about 6 years ago.

Here is a good article on mechanical fuel pumps I found, that might help:

https://dannysengineportal.com/mecha...-need-to-know/

It seems it would be more common for fuel to leak into the oil, and also if there is a hole in the diaphragm, fuel pressure will be low, and you should have issues running normally. He also mentions there should be a weep hole on the bottom side that will leak fuel (or oil maybe?) if the diaphragm is bad.

If you are smoking, but running normally, its likely something other than the fuel pump.

 

Thanks JFmorris, The article explained my problem, I think it`s the rings.

 

Sorry to hear that... fuel pump would sure be easier to replace than the rings!

 

What color is the smoke? What's the car and mileage?

 

Smoke is Blue, rings or valve stem seals I guess

 

I would go with valve seals first because that's a lot easier.

 

Very True, I didn't`t think of that, Thanks! How does a person check those seals?