Mechanical Fuel Pump issue?

[Anchor1800]

While you have it off, why not just rebuild the pump? I rebuilt mine about 10-12 years ago and it provides 3-4 PSI no problem.

If you switch to electric, you will need to add the low oil pressure switch, one more complication.

I did rebuild it back at the start of the summer, same time I rebuilt the carb. I found a broken spring at that time and thought it would help resolve my low fuel pressure issue.

When I took it apart just now I was double checking my rebuild, ensuring the check valves were oriented correctly and all gaskets were installed properly.

[Clucas]

I did rebuild it back at the start of the summer, same time I rebuilt the carb. I found a broken spring at that time and thought it would help resolve my low fuel pressure issue.

When I took it apart just now I was double checking my rebuild, ensuring the check valves were oriented correctly and all gaskets were installed properly.

When you did your rebuild, did you replace the check valves?
I had a fuel issue some years ago where the check valves were not functioning properly -- one was stuck and not opening properly -- a poke with a small screwdriver unstuck the check valve and did the trick. Once the check valves were functioning properly, my fuel issue was fixed. (Thank you, ethanol...). What about the diaphragm in the pump - did you replace that also? When you tighten the two halves of the pump, make certain you've tightened them evening to ensure there are no leaks. (Obvious stuff, I know...)

[joe_db]

https://moyermarine.com/product/mmi-mechanical-fuel-pump-improved-upper-housing-fpmp_11-1_357/

You can buy a whole new pump.

Or another rebuild kit and give it another go:

https://moyermarine.com/product/mechanical-fuel-pump-rebuild-kit-fpmp_13_320/

You don't have to go electric. If my engine had a way to use a mechanical fuel pump I would probably use one.

[Anchor1800]

Resolution, and some humble pie

Last update -
Posting this so others can learn from my mistakes and ensure they absolutely check everything.

The long story short is I did not completely remove the old gasket from where it was stuck to the side of the block. I didn't have a great view and was reinstalling it by feel the first time around and the old gasket was holding the pump about 1/16" farther from the block than it should have. This reduced the work the pusher rod could do to pump fuel.

In hindsight, I suspected that something felt off when I would play with the bail while the engine was running and could only barely feel the pusher rod at almost the end of the range of travel.

So with the old gasket fully removed, I removed the carb and got a few other things out of the way to give myself better access to that side of the engine, it now pumps like a champ. Giving me between 3-5 psi of fuel pressure! And now while playing with the bail while she is running I can feel the pusher rod strongly doing work through much of the range of travel.

Bottom line, all the details are important. I spent much time with the pump itself, and I neglected part of the reinstall that ultimately caused problems down the road. I used my phone to take video from different angles during the second install to get a better view which lead me to pull off the carb to get better access and fully ensure that part was done correctly.

So now I move on to the next issue...

[joe_db]

Good find! That would puzzle a lot of us and a mechanic would probably just go buy a whole new engine.