Cub fuel flow question

Rodger In Sabula · Aug 20, 2009

I developed a "surging" problem with my '53 Cub that eventually results in complete stalling. By waiting a short while, I can get the engine started using complete choke... obviously a fuel problem(?). Upon checking the flow from the tank, how fast should the gas flow into the strainer bowl? It seemed slow to me, filling the bowl in 5-6 seconds. Does that seem normal, or do I need to remove the strainer, shut-off, etc. and try to clear the line?

Janicholson · Aug 20, 2009

With the bowl on and tight, the rate of filling is not going to point to a problem. Remove the bowl and fill a can held under the fittings. It should flow a pint in less than 30 seconds. A good solid soda straw of flow. If it does, the down stream lines need to be checked. There is a screen at the carb inlet that must be clean. If it flows out the carb fitting into a can at the same rate, then that is cool. It should flow out the inlet of the needle and seat in the carb at about 1/2 pint in 30 seconds or more. Good luck, JimN

james rumph · Aug 20, 2009

Do you have a in line fuel filter there as well? If you do that is the problem. All auto fuel filters are designed to work with fuel presure [pump] not gravity feed.

If no filter pull the fuel line off the strainer bowl and make sure it is wide open "clean". I have seen this 2' of line get slowly closed off over the years from the minerals and junk in the fuel.

I had this happen to mine and i just went to the auto part store and bought a new line and bent it to match the orignal one.

Bigdog · Aug 20, 2009

If the carb inlet screen is clean and the flow is good that far remove and clean the main jet on the carb. Clean both openings with a soft copper wire such as a small telephone wire. Do not use anything made with steel you do not want to damage the openings. You probably have a small piece of dirt partially blocking the jet.

Tom Fleming · Aug 20, 2009

Sounds like a sticky float to me. when it starts to sputter and "search", try pulling the choke out 1/2 way or so. If it smooths out again, take the handle end of a small hammer and moderately tap the sides of the float bowl on the carb. if it will run smoothly with the choke off after that, you definately have a sticky float or needle valve.

This of course is after you have determined you have good flow into the carb.

IMHO.

Cub fuel flow question

Rodger In Sabula

New User

Janicholson

Well-known Member

james rumph

Member

Bigdog

Well-known Member

Tom Fleming

Well-known Member

Similar threads