Well its a long story, but I own a 1980 175 Merc, that for 10 years didn't really run right. It would run out of fuel at lower rpm's

Here's what I did in order to try and fix it over the last ten years.
Change primer bulb
Rebuilt fuel pump
Tried external fuel tank
Cut open my inboard fuel tank to see if I had an anti-syphon device, none
Fule pick-up fine
change fuel line
rebuilt fuel pump again
change primer bulb again
put clear fuel lines between primer bulb and fuel pump, and fuel pump and carbs
no bubbles between primer bulb and fuel pump
small bubbles would develolpe inside fuel pump, and start coming out of top carb line, then a rush of air starting from the upper, and middle carb would happen, going in the direction, carb to fuel pump. This takes 30 seconds to happen.
I go locate a used fuel pump, since at this point I think the fuel pump is porous, I rebuild it, put it on, and the same exact thing happens.

I throw my hands in the air and start cursing, not at anyone or thing, and I am ready to give up. It's been ten years, and I still don't have the !@#$#@ motor running right, it won't idle, and I need to go trolling to catch a record muskie already.

I am staring at the primer bulb....again....and a voice pops into my head, and says take the primer bulb off completely, so I argue with the voice and say, that makes no sense, then the voice says try it, you might learn something (lol) so I take it out.

Bingo, the motor starts right up every time, idles like a champion, and I picked up 200 rpms on the top end, which means I was probably running lean. Even if the fuel pump is dry, and carbs are dry, and fuel lines are empty, it only takes 4 seconds of cranking to fill the lines and have the motor start. I have run 90 gallons of fuel through it since then, and it runs perfect.

I still haven't caught the muskie yet though.