1980 E35ECSM carburetor operation?

I am in process of overhauling carburetor and the whole fuel system of my OB and have a few questions about its operation. It is definitely Type IV as listed in SELOC manual and I am now waiting for a new float chamber and high speed orifice as it would not come loose without breaking.

I can well how understand how fuel enters the float chamber from the pump and is pulled to the throat through the high speed orifice, but how the low speed jet is fed? Directly by the pump? (If so, there might be something blocking the fuel supply there.)

While disassembling I found out that the fuel inlet valve was very badly worn, no other obvious problems. The OB had such a problem that every now and then it would simply not start or "promise" no matter how much cranking and then just start and run again after some time. The last time I experienced this I was able to confirm that atleast some spark was present, did not have proper tester along then, and that fuel not flow into engine. Primer became hard and fuel line pressurized. Could this problem have been caused by the inlet valve? Or blocked low speed jet more likely?

Re: 1980 E35ECSM carburetor operation?

low speed < idle > is fed from the float bowl. With the float bowl removed from the carb body, note the screw holes at the four corners that attach the bowl to the carb body. Now look for a fifth hole into the carb body, that's the passage way up to the idle mix chamber. Your low speed mixture needle controls the gas mix in this chamber. Pop out the core plug and you'll find 3 or more small holes that enter the carb throat at or behind the throttle plate. These need to be open clean. The passage from the carb bowl needs to be open and clean.

A stuck needle valve < inlet valve > will prevent fuel from entering the carb bowl. A blocked orfice plug < main jet > would prevent fuel from leaving the carb bowl. Don't know the liklihood of one occuring versus the other.

Re: 1980 E35ECSM carburetor operation?

bowl was definitely full of fuel, so maybe inlet was blocking flow and something blocked the low speed jet, preventing supply to engine. I will try to figure out how it is supplied and ensure that the path is clean. Thanks, let's see will it help.

Re: 1980 E35ECSM carburetor operation?

Haven't received the parts yet, ordering intercontinental causes delays. Meanwhile checked through the assembly and found no evident problems. Compressed air flows from bowl for low speed jet and from the jet into throat. Damn, I had thought that the needle valve would receive still liquid fuel. I am going to pry open the plug sealing the low speed chamber also as a new one is included in the kit and I have still some time before the parts arrive.

Seloc manual talks about bearing for low speed needle, but EPC does not show one meanwhile the kit includes it. I could make anything come out either. Should it be there or not?

Flooding caused by the worn inlet valve seems also a likely cause for the occasional starting problems.

Re: 1980 E35ECSM carburetor operation?

the carb diagram at marineengine.com doesn't show a bearing for your low speed mixture needle...carb kits contain parts for several models and it's common to have parts leftover after a rebuild