Johnson RD-19E weird flooding

I'm wrestling with an RD-19E big twin that has the old style OMC fuel pump, fed by a pulse hose from the bypass cover around the plugs and to the pump on the starboard side. I've cleaned and reset the carb twice. Got it running by rope starting it this morning and it kept flooding...I've checked the carb float and seat and they work when the carb is off the motor. Weird part is if I clamp off the gas line and let it run off what's in the bowl, it settles down and runs good..good enough that I could set the high- and low-speed needles. Unclamp the gas line and it floods and dies very quickly. Can these old fuel pumps over-run the carb/engine if something is wrong inside...like a bad diaphragm?

Re: Johnson RD-19E weird flooding

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Re: Johnson RD-19E weird flooding

Which gas line are you clamping off?
If it "fixes itself" when Either the main line to the fuel pump or the line from the fuel pump to the carb is clamped, then the problem is the float/needle valve.
If it fixes itself only when the main line is clamped, but not when the fuel pump-->carb line is clamped, then the fuel pump may be leaking into the crankcase.
You can pull the pulse line on those and see if there is gas getting into it.....

Re: Johnson RD-19E weird flooding

Thanks txwhaler...it fixes itself when you clamp off the line from the fuel pump to the carb. I know the needle is seating okay...I rechecked the carb insides after posting yesterday. Must be the float is not floaty enough...guess it's time to invest in a carb kit, really needs new packing washers for the high and low speed needles. Hope the carb kits are available and come with a replacement float. I'll pull the float today, test it in a can of gas, and maybe jack with the float height adjustment if it does float good.

Re: Johnson RD-19E weird flooding

Went back through the carb today...tried two floats that bob in gas pretty well, used another needle with spring, used a soft gasket on the high-speed tower...adjusted the float and it will seat and shut off the gas when the high-speed needle is seated. Can't open the high-speed more than 1/4 turn out or it floods like a big dog again. Guess the seat on the high-speed needle is toast. Looks like its carb kit or new carb time. When it fires over and runs/answers the throttle, it runs well for about 5 seconds then dies. Pulled the pulse line to the fuel pump and no gas there...so I guess the fuel pump is okay. The mystery continues...