73 1150 fuel pump/flow question

[Kailofsouls]

So I replaced the dual fuel pumps on my motor but I think I might have my check valves backwards I'm not sure. When I run the motor after 2 minutes or so if I don't squeeze the primer bulb the motor will die. Vent is clear, tank is clean, all fuel lines are brand new, new bulb, and inline fuel filter. Carbs are clean, and the levers in Carbs are set. My question is. Does the fuel flow in a loop gas to top pump out to carb 1 to 2 to 3 to bottom pump back to top? Or fuel to top pump to carb 1 AND bottom pump to carb 3? I've attached a picture to try to make it easier to understand what I'm saying. I confuse myself sometimes

 

[Chris1956]

I had an 850 with those fuel pumps. I never had to do anything to them, so I am not real familiar with them. I would expect fuel to travel thru the upper furl pump to the lower fuel pump and to the upper carb.

When you squeeze the primer bulb, I expect bottom and top carbs to fill first and then mid carb from both top and bottom.

Hope that helps

 

[racerone]

The pressure operated pumps are very reliable.----Rarely fail.----Might need a new $5.00 diaphragm one in a while.

 

[Kailofsouls]

The reason I replaced them was that I replaced all fuel lines, and had to remove the pumps to do it. Figured while I was there that I didn't know how old any of it was, and I damaged one gasket so I replaced everything. The issue is that everything is clean and new. There's no reason that I can find for losing prime. Compression is good (over 120 all six cylinders). Carbs are spotless. I even decarboned the motor (one gallon of gas to one bottle of seafoam). New plugs, new wires, and she idles at 600rpm so I believe the reeds are fine as well. She just won't stay running.

 

[Chris1956]

An air leak in your fuel line will cause those pumps to pump air. That should be your next check.

 

[Kailofsouls]

I'm fairly certain that I don't have air in my fuel lines all new lines are hose clamped on. I'm just trying to figure out the direction of fuel flow through the check valves. Everything primes up nicely, but it's not drawing fuel like it's supposed to so it can stay running. Also my quick connector is a new attwood plastic connector for mercury.

 

[Chris1956]

Gee, if you can fill the carbs by pumping the primer, the check valves should be in correctly, at least in one fuel pump. Maybe they are backwards in one fuel pump, starving the motor?

 

[Faztbullet]

Make sure you installed the correct diaphragm kits as they look the same but gaskets are different