Carb floats question

The only thing that is going to help (stop) this problem is for you to remove the tank and have the crud removed from the inside and relined inside, or you will be having the same problem from now on.   ( I know this from EXPERIENCE )

There was 5 minutes of fuel for idling in the bowl. The in line filter IS a factor in the fuel starvation but not the only factor. The line is probably nearly filled with varnish and rust. The carburetor inlet screen is suspect. A warped float can drag on the side of the float bowl and stick everywhere. A rubber tipped float needle can stick closed. A float needle without the rubber sometimes doesn't seal well. The in line filter can be plugged by water and rust. There can be something solid sucked over the fuel inlet at the gas tank. The gas tank cap can be failing to vent (many new caps don't have the necessary vents) though it should run longer than 5 minutes when the gas cap isn't venting.

You can check for fuel starvation, if it recovers momentarily from the rough running if you pull the choke on that's a good indication.

Dragging floats and sticking needles sometimes respond to tapping the side of the float bowl. Dragging floats sometimes leave marks inside the float bowl.

I like to check for proper float and needle operation with the bottom of the carburetor by blowing into the fuel inlet (by mouth, not much pressure) and by lowering and raising the float to see the low pressure opens the needle and gently raising the float shuts off completely.

You might want to modify the sediment bowl connection to the tank with a tube to leave some gas in the tank (maybe a quarter inch) and with a screen above that to make an inlet somewhat more resistant to floating debris. Your cattle magnet could have settled over the inlet blocking flow.

Common in line filters are used in systems with 3 to 8 psi pumps with carburetors or 30 to 40 psi pumps with fuel injection. Gravity has no where near that pressure. There are gravity rated in line filters, but not at wallyworld.

Gerald J.

Yep, the NAPA on my B works fine. I don't remember what the part number is off the top of my head. It was really reasonable.

I got tired of cleaning out the tank on my D14. I drained the gas, removed the sediment bowl and flushed the tank with the garden hose several times. After draining the water and reassembling, I had to empty water collected in the bowl several times. I also started putting a cup of used oil in every 5 gallons of gas. Been a year and a half and haven't had any more issue with the fuel.

Thanks for all the replies everyone.  This really is a great place for info.
When I posted I was at work and didn't have a lot of time, and left some info out.  Sorry about that. 
I did get the inline filter from NAPA, and told them what it was for.  As far as I know it's a gravity filter, and when I pull the line from the carb and open the valve I get really good constant flow.  The old factory line was getting built up with rust (high cholesterol I call it) and I think I have better flow now. 
I'm not a mechanic, (electrician by trade) but I honestly think that my problem now is the float sticking.  The guy that put the rebuild kit in for me is a well known tractor mechanic and a family friend.  I'm 100% sure what he did is right, but I did not buy a new float kit.  Just the basic carb rebuild kit.
What leads me to the float is the fact that when I had the carb plug pulled out I had no flow until I tapped on the outside of the carb.  I put the plug in and let it sit, and shortly after that I had gas leaking out of the carb.  I started it and let it run, and it ran great.  Then it started doing the run for awhile and stutter to catch up thing. 
Tomorrow night I'm going to pull the carb again and adjust the float to hopefully get it not to catch. This will be trial and error for me.  Is there any way to tell if it's set right (not catching) before I put it all back together? 

Thanks again.

Had the same problem recently with a 170. It was the rubber tipped needle that was sticking. Apparently some of those react with the 10% ethanol in the gas and get sticky. We tried three different needles and finally got an all metal one and that fixed it.

Good test, Wes.

Gerald J.

Next time it's apart try lightly lapping the needle and seat with some engine valve lapping compound or metal polish. Make sure to get all the lapping compound cleaned out when you're done.

who has metal needle and seats available for most carburators

I found a wide assortment of float needles and seats in a marine and carburetion shop on South Broadway just south of St. Louis one time. I just took the old ones with me and he took them to the back room in reappeared in a few minutes with matching new ones. In theory a good NAPA might be able to do that too, but probably not in the real world.

Gerald J.




Edited by Gerald J. - 27 Dec 2011 at 8:59pm

And once again, thanks to everyone for all the advice.  This site has been a great help!