'76 30hp - Carb Bowl running dry?

Engine stopped after running for about an hour, anchored and watched the sunset. Wouldn't start-got home on trolling motor. Removed carb, cleaned/inspected thoroughly, checked fuel lines and bulb for flow, cleaned inline filter; made sure float adjusted properly, still wouldn't start. Finally replaced fuel pump (two stage) diaphragm and gasket with new - old one was shot, stiff, losing rubber (Note to self: replace diaphragm at less than 20 year intervals!) Absolutely no hesitation when started up! Boom! like new. Idled like a champ - no problem! Out on the lake gave it WOT and ran like a scalded cat for . . . . .about 40 sec's . . . . .lost power as if running out of fuel, so backed off throttle (didn't die) and idled for about 5 min, then WOT again (bat outta hell!) - then same thing . . . motor idles along at low speed (1200 rpm) just fine . . . .will run at 2000 rpm for about 4 min is all w/o dying .. . . . haven't checked compression . . at a loss . . .definitely unrestricted fuel to pump and to carb - all vents and jets/orifices clear . .

Sounds like the vent line is clogged?
Or the fuel line is obstructed/clogged.

Ethanol has a way of delaminating the inside of the hose.

The squeezie, make sure the one way valve isn't clogged or
broken.
Even brand new squeezie's can be bad right out of the box??

I also have noticed squeeze bulb check valves failing from ethanol too. Damn things are expensive now but terrible quality. Here is another example of ethanol damage. Destruction of rubber. These are mounts from a Johnson 15 horse.

timguy said:

I also have noticed squeeze bulb check valves failing from ethanol too. Damn things are expensive now but terrible quality. Here is another example of ethanol damage. Destruction of rubber. These are mounts from a Johnson 15 horse.

Click to expand...

Really I guess that damage has nothing to do with them sitting in the exhaust path. A bad design more than anything subjected to heat and exhaust . With that comment back to the 50s you go.