Running out of Fuel

[omcjunkie]

I have a 1975 150 mercury inline 6 that is running out of fuel. The motor has sit for a few years and I have gone through the carbs and rebuilt them with new floats/ seats/etc ,I also have rebuilt both fuel pumps with kit, new fuel line through out mtr. Have a new fuel line on engine to a 6 gallon tank. The issue is when I pump up the fuel line the motor will crank and run until all fuel is out of line and dies, if I pump the line I can make the motor run a little longer. The tanks works on another mtr fine and I replace the fuel line twice with the same results. What am I over looking? Thanks

 

[tlewis1]

I'd be looking at both those rebuild fuel pumps again and confirm they are operating as they should. I believe the fuel pumps work off crankcase pressure so I would also be checking to make sure I have adequate vacuum as well.

 

[tavacska]

It seems to me, the fuel can not get into the floats bowl without you pumping manually. I wound pull the fuel lines off from the carb and check if fuel comes out when cranking. This is to check the fuel pumps.

 

[jhopkins]

I just went through this same issue with my 1988 35hp and it ended up being in the fuel pump. The retaining pin (wall anchor style) that holds the diaphragm had came out and blocking fuel from entering the fuel filter unless pumping the primer bulb. After a lot of research I found that the new kits require the pump body to be slightly drilled out to allow the center pin to be pushed down into the retainer allowing the fingers to be spread out and hold the diaphragm down correctly.

 

[jimmbo]

I would go through both of the pumps again. You did get the hoses all placed correctly? You did set the float linkage and drop as per spec? Initial setting for the idle mix screws 1 1/2 turns out?