Vapor lock?!

[jim cancil]

I think - I remember as a kid, people putting ice on the intake manifold to condense carb output when tfuel became gaseous due to excessive temps around the intake...

I've been chasing a ghost for a couple of years. Yesterday, I was able to continue to cut pasture - well beyond the time the tractor typically begins to loose massive amounts of power and begins to sputter and quit. I thought I narrowed this to alcohol in the fuel they sell us to "cut emissions" and the prospect of the float needle tip swelling.

The difference yesterday was the temps were in the upper 60's and the wind was in the mid-20's vs. our typical 80-90f. with little or no wind. Same fuel .. same tractor .. same settings .. Different Result. The weather seemed the only new variable...

Anyone have any experience with 'vapor lock' that is not muddied in a 50yr memory? Thanks.

Jim

 

[tractor fixer]

adding a length of rubber hose to a metal fuel line will keep the gas liquid. installing a clothes pin to the metal fuel line will accomplish this also.

 

[slinMI]

You seam to be refering to carburetor icing, not vapor lock. Vapor lock only occoures within a fuel pump. On a gravity feed fuel system it can not happen. Carburetor icing is caused by the air passing through the venturi and the resulting low pressure causing a temperature drop. I basic form of refriduration. This causes the carburetor to become very cold and with the right temperature and air moisture ice will form in and arround the carburetor and choke the engine. The fix for this condition is heat baffles and ducts to direct exauste heat on to the carburetor. Some others may have comments on fixes.

 

[Fred Hart]

Jim,
when the tractor quits running have you ever taken the gas cap off and had a vacuum sound.

Could be someone has put a car (non vented) gas cap on old tractor, these old tractors must have a vented cap as they have a gravity flow fuel system.

A non vented gas cap would allow tractor to run for a while before you would build up enough vacuum to stop the flow of fuel to carb.
After tractor quit running and sit there for awhile air would bleed in and fuel would flow again.

Good luck and let us know what you find when problem is fixed.

 

[Jerry/MT]

I have a TO-30 that I operate in temperatures of 100F to -20F and have never experienced "vapor lock". As long as you fuel line is well separated from the hot part of the manifold, you should not have a problem.

The next time the engine dies on you, immediately (I mean right when it happens) check the spark by pulling the center high tension lead from the distributor cap, holding it near a good ground adntrying to start. If you have a FAT, BLUISH-WHITE SPARK, the color of lightning, the ignition is OK. If it"s not, you most like ly have a problem in the primary ignition circuit. If you have a 12V electrical system, make sure that you have a real 12V coil(like NAPA IC-24SB ~$15)

Then check the fuel delivery by opening the plug at the bottom of the carb abd see if you have a CONTINUOUS flow of fuel for at least 45 seconds. If it driibles or is intermitent, that"s not good.

Between these two checks, you can determine whether your problem is ignition related or fuel related and take the appropriate action.

 

[Jerry/MT]

That part number is IC-14SB not IC-24SB

 

[el61-1947]

Jim , I just had a to-35 through my shop this summer that I spent several days discing and almost 30 gal of gas to figure out what the problem was. I never would have believed what the cause was by the way it performed under a load , if you exhaust all efforts to repair your problem shoot me an email and I'll tell you. It was not a faulty coil or starvation of fuel.