UPDATE: SOLVED! Only runs if tank 1/2 full +?? Carb problem?

Hi All, Thanks for all the input. I was away and computer free for the weekend so apologies for the delay. There is no fuel pump, gravity fed, so I am going to wait for it to happen again and then investigate in order: 1) air lock/vent in tank/cap 2) fuel filter (too fine?) 3) the whole fuel line end to tend 4) carb.

I will post what I find out.
 
Common issue on gravity systems is wrong fuel filter. Many paper type filters have small enough pores that the fuel surface tension causes fuel to stop flowing at a certain level in the tank. Also, a fuel line that ruses up higher than the bottom of the tank will cause fuel flow to stop at the height of the fuel line.
 
Scrubcadet10 said:
"I'm back, Jack"!


Generally on gravity feds i usually fit the red or white briggs filters, however i've also used Wix 33011 on my own gravity fed systems with no issues.
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The stens paper filter seems to work ok with gravity systems but i fit the red screen filters on customer machines just to be sure. Every year i get a couple mowers in where cust wanted a better filter and installed a paper one and then have fuel flow problems.
 
Probably tens of millions push mowers came with no type of fuel filter. When equipment started having fuel pumps it was easy to add a filter. The original filters were there because metal tanks were prone to rusting. With the switch to plastic tanks rust isn't much of a problem but filters don't hurt anything so they stayed. I have changed hundreds of fuel filters and the only plugged up ones was from water or the jelly like phase separation goo you get from old E-gas. I have cleaned hundreds of carbs and i i can't remember the last one that actually had a problem from dirt. Usually old gas is the problem. Most fine dirt settles out in the bowl of float type carbs and not cause a problem.
Use or don't use your filer of choice. Whatever works for you.
 
bertsmobile1 said:
I think Steve was too busy emptying those cans behind him when he filmed this one.
Yes a paper filter will filter finer than the screen
However if the crud is fine enough to pass through the screen, it will also pass through the main jet & on most carbs the idle jet as well
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People watch this and then go out and put a filter on thay MAY or MAY NOT work. Depending on the height of tank above the carb and the micron size of the paper element things might not work properly.
 
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