Engine stumbles on startup

[ArtJ]

Thanks for the new posts guys

I will keep in mind all suggestions

BTW my carb is extra hard to reach because of FWC, Oil filter and cables for
4 batteries and Oil cooler


Best Regards to all

Art

[capnward]

If you can reroute some of those items that restrict access to the carb, your life will be easier, because carburetor removal is a common task with these engines. I had an oil filter once but removed it, and never saw the need for an oil cooler. I just change oil every 50 hours. Make sure your scavenge tube is tight. Float valve inspection is in your future. Check floats for leaks. Moyer's carburetor rebuild kit includes a small pointed wooden dowel for dressing the float valve seat. You may be able to make one without buying the whole $100 kit. (Buy the kit anyway) It is a hardwood dowel 3/16", tapering down to a point in 5/16". A pencil sharpener might produce the right taper, I don't know, but it is a similar angle. It should match the point on the valve needle. But dressing the seat won't solve the problem of junk in the fuel. New filters and a fuel pressure gauge would be good.

[ndutton]

Art, a good practice is to not re-use a fuel line "end" as pulling them off of a barb often tears the inside a bit. And these bits often get stuck in the carb especially the needle & seat.

I prefer to use flare fittings for fuel lines that require frequent disassembly such as at the carb inlet.

[ArtJ]

Carb fixed

On Reviewing Don's short video in carburetor troubleshooting,
The number one most common issue is a stuck float.
Don's first solution is to remove the main passage plug and flush with
fresh fuel by using the priming bulb or the electric fuel pump
bypassing the oil pressure shutoff valve, which i did by use of a jumper
clips from the lead on the pump to the battery terminal on
the starter and let it run for 20 seconds for a good flushout.
This had immediate results and the engine started immediately
and smoothly wit no fuel dripping from the carb barrel.

Cautions I shut the main power switch off before adding jumpers and again'before removing- don't want a spark to occur wit fuel vapors.
I also cleaned up the bilge thoroughly before starting the engine
and ran the blower until i was certain no vapors were present.

Kuddos to Don Moyer tips!

[capnward]

Glad the fix was an easy carb flush to unstick the float valve, for now. No carb removal required. Don's videos are worth every penny. The question remains why did the float valve stick?
This is another reason why I am keeping my mechanical fuel pump. You can manually flush the float valve briefly without electricity, before starting. No danger of sparks in fuel vapor as when bypassing the OPSS with the power switch on, a situation you wisely avoided. Also, no fumes or spills are created trying to direct fuel into a jar from the main passage, although that is a good way to look for fuel problems. You didn't report any particles in the gas you pumped through the carb for 20 seconds, so that's good.
Using the hand bail underneath the mechanical pump forces gas past the float valve until the floats rise to close it. I like to pressurize the fuel line this way before starting, as it starts with less cranking. This acts as a priming bulb, but is USCG approved. You can hear the gas squirting through the float valve until the bail has no resistance and the fuel pressure gauge goes up. I believe this flushes the valve and helps keep it from sticking. That, and the use of MMO in non-ethanol fuel. IMO, the MMO keeps the rubber tip of the float valve needle lubricated, and non-ethanol fuel doesn't degrade the rubber.

[Al Schober]

Come on guys - the problem is NOT a stuck float. It's smutz in the float valve seat. When you remove the main passage plug, the bowl drains and the valve opens fully. When you hit it with fuel, the smutz is flushed out of the valve seat (usually) then the valve will work again.
I have heard of floats that develop pin hole leaks, get gas in the float, then won't close the valve. But I've never seen one.

[edwardc]

...I have heard of floats that develop pin hole leaks, get gas in the float, then won't close the valve. But I've never seen one.

I have. The right side chamber is half full of gas and sloshed when shook next to the ear. The float is balanced on the screwdriver edge, and you can see that the balance point is way off-center to the right.