cub fuel problem

It appears there is the fuel line is getting a vacum lock which stops the flow of gas. If the tractor sits idle a few minutes the gas will again begin to flow. I can get the gas to flow again immediately if I disconnect the fuel line and syphon it by mouth gas will flow fine the tractor will restart and run 5 to 10 minutes before the same thing happens again. I'm open for suggestions, Thanks, JB

You wrote: "I have 55 cub. It starts and runs fine for about 5-10 minutes then quits. I can see that there is NO fuel getting to the carb when it quits as the clear fuel filter is dry."

First, in a gravity type fuel system as a Cub is equipped with, fuel filters only accomplish one thing - restrict or completely prevent adequate fuel flow to the carb from the fuel tank.

Suggestions -

1. REMOVE auto type filter, or even lawn mower type filter - it is basically useless.
2. If you must have the fuel filter, then ensure that the fuel filter is at least 1 to 2 inches ABOVE the Fuel Filter Screen in the Carb Inlet.

Secondly, I would suggest that you visit the Cub Manual Server at www.cleancomputes.com/Cub/index.html and then read Lurker Carl's Carb Fixes series of articles which can be found under the Maintenance Tips and Techniques link.

You may also find that the little tiny almost impossible to see hole in the END of the Main Metering Jet may be plugged. This is a common and commonly overlooked item whence cleaning the carb.

As far as a vaccum lock, you have to have a pressurized system to essentially have that. The only instance that comes to mind where fuel flow might be impeded and mimic vaccum lock would be if your gas cap's vent holes are plugged. The cure for that is two fold. If you have the old original style cap, then I would suggest you click on the Navistar Free Gas Cap Offer Form link and fill it in after you print it. In about 4 months or so (last shipment was about 2 months ago) you will get a new one. Check the vent holes in this cap and make sure they are clean as a whistle. If you have the new style cap, make sure the vent holes are clean.

You wrote:

"I can get the gas to flow again immediately if I disconnect the fuel line and syphon it by mouth gas will flow fine the tractor will restart and run 5 to 10 minutes before the same thing happens again. I'm open for suggestions, Thanks, JB "

Even though I am by no means a mechanical whiz.. in fact I am mechanically challenged, I do know this. What you describe can only be caused by a couple of conditions... these are:

1. Addition of an extraneous in-line fuel filter.
2. Plugged vents in a gas cap

Please try these two cures... and let us know what happens.....

You've got a fuel flow problem at the tank. Either its vapor-locking because the gas cap's vents are plugged, or you've got a serious crud problem inside the tank.

"Blowing the tank out" with air, all you're doing is stirring up the crud. You might get a little bit coming out the neck, but most of the crud just bounces around inside the tank and goes right back to the bottom. Especially the big pieces.

You may need to take the gas tank to a radiator shop to have it cleaned.