Otto,
Actually, I probably had the same problem on the mechanical pumps as you.
I did purchase a new one(s) with most not working at all.
Had one work for a bit but seemed to be pumping air so put my original one back in and that seems to work best.
I should say the Elect fuel pump is an axillary pump that I use just to prime the line after not running for a while and to try and overcome any vapor lock issues,
I can turn it off and just use the mechanical pump for driving.
The electrical pump has a check valve bypass for the mechanical pump.
I did this after reading some recommendations from others on the pump.
Sorry for any confusion.
