1974 50Hp not using all gas in a tank.

[wrunner74]

Hello all:

The past few times I've been out, my motor sputters and dies when there is still about 1 gallon in the tank. The vent is open and I can pump the bulb a few times and get it to keep going a little, but it will quickly die again. If I switch over to the secondary full tank, it runs great, until it gets down to about 1 gallon left in a six gallon tank. Any ideas what would cause this?

 

[GA_Boater]

What tank? Plastic portable? Some portables have a built-in reserve and to use the reserve, the tank is tipped to flow the reserve fuel into the primary area.

 

[wrunner74]

GA - it's an older 6 gallon metal tank. I'm going out for a test run today so I'll bring a chunk of 2x4 along to prop up one end...I assume you raise the end opposite of the pickup. It's never done this before. Always sucked the tank down to a few cups worth. When I refilled recently, it only took 5 gallons. Thanks for the tip.

Wondering of this is common or if anyone else has similar situation.

 

[GA_Boater]

Take the pickup out and see if it has shortened by the screen fixture come off or has any extra holes from rust..

 

[GA_Boater]

Thought a photo would help. This may not exactly match your tank guts, but it still shows the pickup and screen.

 

[wrunner74]

I think I may have figured this one out and it's really stupid. I usually just loosen the vent nut about a half turn or so. What happens is that the weight of the nut combined with the any suction makes it reseal the tank. If I gently lift up on the nut and you can heard air sucking IN, not blowing out as would happen on a non used tank. So, I just backed the screw all the way open and walla! Seems to work better now. Duh! I will be inspecting those tanks soon though...thanks for the pics.