Briggs Outboard Carb Adjustment
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northcreeek262
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I'm assuming that this exhausts through the lower unit like most outboards. If so, make sure that it is not plugged by a rodent, mud dauber, sea weed, etc. Nothing goes in if nothing gets out.
sgkent
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more likely a carp
Nope. Exhaust is on the side. Briggs managed to bolt a foot to the bottom of a vertical shaft 5hp motor. I can get in real shallow water.
I don't even know where to begin to check for leaks. Surely can't do it while the motor is running.
Took the boat out today and it ran, but I had to play throttle with the choke. I don't have an intake manifold. Carb bolts directly to the cylinder head. Could I have a bad head gasket? Fuel pump is newer, so I doubt that's the issue. I could have gotten a bad one, but it runs wide open with the choke in the wrong place, haha.
Sprayed carb cleaner everywhere I could think to with zero change. Around the carb mount, around the breather, and around the breather tube. The only place I didn't spray was the head gasket.
I'm going to replace the exhaust gasket (needs it) and the breather assembly/gasket. Maybe it's sucking in air around that somewhere. I can't find anything else unless the head gasket has totally failed.
I'm going to replace the exhaust gasket (needs it) and the breather assembly/gasket. Maybe it's sucking in air around that somewhere. I can't find anything else unless the head gasket has totally failed.
sgkent
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some carbs the breather powers the fuel pump diaphragm.
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Yes the crankcase vacuum powers the vacuum operated fuel pump. The breather operates the same as the PCV unit on cars which allows the engine to exhale but not inhale. This way the engine blow by gases are vented from the engine and vacuum impulse is created after the exhale of these gases. Without this full vacuum impulse the fuel pump will not operate properly so a defective breather assy can cause problems like the one the OP had.
It is just not a common problem for these to fail.