I have tried most everything I can think of, short of rebuilding the carb. Removed and cleaned the fuel bowl, checked the float to make sure it is seated. The carb is still leaking out of the bottom, drip by drip. Even with the fuel shut off it will empty the tank in a few days. Not a full one obviously, I am putting only a gallon in at a time to test it. I assume the shut-off is not "shutting off" so fuel is draining into the carb, as IT leaks. Any ideas? Thanks
- Thread starter nydolphin
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glennster
Well-known Member
you will prolly need to replace the sediment bowl assembly to get the fuel to shut off first. then tackle the carb. either there is a problem with the float hanging up, float level set too high, or possibly a hairline crack in the fuel bowl. with the fuel bowl off the carb, set it up on a table or something so it sits level, the fill the bowl with gas and see if it is leaking thru the casting or possibly the main load jet area. if not, look to the float, and needle and seat.
rustyfarmall
Well-known Member
Is the needle valve SEAT screwed down tight and is the gasket good? Is the float in good condition? Is it set to the proper height and is it free to move up and down? Carburetors are much more complex than most people realize, and proper adjustments are NOT a guessing game.
Also, obviously the sediment bowl fuel shut-off is not working. A complete, new sediment bowl assembly is not that costly, and is the easiest, quickest way to solve that problem.
Also, obviously the sediment bowl fuel shut-off is not working. A complete, new sediment bowl assembly is not that costly, and is the easiest, quickest way to solve that problem.
I have decided, after taking the sediment bowl apart, that yes I should replace the entire thing. This will solve the gas getting TO the carb. I assume Rusty that you mean the horizontal adjustment screw, directly off the front of the carb, as the needle seat? This has a felt gasket around the threads on the outside of the carb. Is that what is supposed to be all the way in? I always considered that a mixture adjustment because when turned even a quarter turn affects the idle. Pardon my inexperience with these but I do think a carb disassembly is necessary for me to get familiar with it. I hadn't considered the cracked casting possibility glennster, thanks. Looks like I have some work ahead of me.
rustred
Well-known Member
most probable cause would be needle&seat. it is located at the carb inlet behind the brass screen. BUT you need to remove carb and separate halves and remove float, by pulling out pin. then you can remove needle & look at it. the metal ones usually show the wear where its seating. the seat unscrews. best to just o/h the carb, as you will need to soak it in carb cleaner to dissolve junk out of it.after soaking wash in warm water and blow out all passages with air.rest later.
Janicholson
Well-known Member
The needle/seat Rusty refers to is the internal valve attached to the float inside the bowl. The load adjustment(front bottom of carb)you refer to is not it. The original seat and most replacement seats are brass. Original needles were also brass. Over the years the needle wears into the brass seat, deforming both to an ever wider contact area. Eventually this leaks, allowing fuel to overflow the bowl.
The new needles are often made from Viton (a relitive of neoprene with a harder compound) These will often work well, but have been known to have molding marks on them that can weep fuel slowly. Most do not, but when they do it is frustrating. With the bowl off gently holding up the float and turning on the fuel will allow you to see directly the rate of leakage, and how much light pressure it takes to stop it.
The needle/seat should not leak, and the fuel shutoff as described (sediment bowl) should be replaced to allow real control every time it is shut off. JimN
The new needles are often made from Viton (a relitive of neoprene with a harder compound) These will often work well, but have been known to have molding marks on them that can weep fuel slowly. Most do not, but when they do it is frustrating. With the bowl off gently holding up the float and turning on the fuel will allow you to see directly the rate of leakage, and how much light pressure it takes to stop it.
The needle/seat should not leak, and the fuel shutoff as described (sediment bowl) should be replaced to allow real control every time it is shut off. JimN
One way to check for a crack in lower casting is to put a fitting in the drain hole and a clear hose running up beside the bowl and higher.
Then you can see if the fuel level comes up higher or lower than the overflow. If it stays lower than the overflow and still leaks there's a leak in the bowl somewhere. You probably just need the carb gone through the.
Then you can see if the fuel level comes up higher or lower than the overflow. If it stays lower than the overflow and still leaks there's a leak in the bowl somewhere. You probably just need the carb gone through the.
rustyfarmall
Well-known Member
Pay no attention to that number. The number you need is on the small, round brass tag that is riveted on to the area where the governor tube attaches, and even that number is somewhat irrelevant. I keep only two kits in stock. A very basic, very inexpensive kit that contains only the gaskets and a needle valve and seat, and the super complete kit that contains absolutely everything needed, and that kit can be used for every M carburetor that comes across my work bench.
rustyfarmall
Well-known Member
I will just add that not all NEW sediment bowl assemblies are created equal. Some of them are junk from the get-go, and WILL NOT stop the flow of fuel when shut off.
I did take the carb apart, as suggested, checked the float. The needle appeared to be seating properly but when I put the carb back together it continued to drip. It is overflowing and it doesn't help that the shutoff isn't working. Must be the needle...
Ok. I just got back from the local store and bought a new sediment bowl/shutoff. It is not like the 'original' but if it shuts off, I don't care. Hopefully it isn't one of the 'junk' types you referred to. I also tried to get just the needle and seat for the carb but had to buy the entire kit to get it. I hope I got the right one. My throttle body says 8557D. They had a kit for and 8867-DX with no cross reference. It looks like the same size and shaped gasket. I'm hoping... anyone know or have a cross reference? Thanks for all the advice.
Ok. I just got back from the local store and bought a new sediment bowl/shutoff. It is not like the 'original' but if it shuts off, I don't care. Hopefully it isn't one of the 'junk' types you referred to. I also tried to get just the needle and seat for the carb but had to buy the entire kit to get it. I hope I got the right one. My throttle body says 8557D. They had a kit for and 8867-DX with no cross reference. It looks like the same size and shaped gasket. I'm hoping... anyone know or have a cross reference? Thanks for all the advice.
rustyfarmall
Well-known Member
The gaskets are all the same. Likewise the needle valve and seat, so no problem there, but if you bought that sediment bowl assembly at a farm supply type store, you most likely are going to be disappointed.
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