Small Engine (lawn mower) Stalls

I have a Toro 5 1/2 horsepower 4 stroke mulching "Super Re-Cycler" lawn mower. I have a current problem where the machine will start and run fine for about half an hour, then it stalls, sounding as if it has run out of gas. I then prime and re-start, it starts running strong for about fifteen seconds and stops again. I can keep the engine running by pumping the primer while running, but, as soon as I stop priming it stops again.
I will be taking it apart today to have a look at it. If anyone has any suggestions on what to look for, that would be great.
It really seems like it is starving for gas, loosing it's prime somehow. Could it be something as simple as a blocked fuel line?
There is no gas leaking anywhere. I'm pretty sure the plug is okay. and filter is okay.
I seem to recall that I replaced a cracked filler cap a few years ago when I had similar symptoms.
Thanks Andre
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It does sound like a fuel blockage of some sort. Perhaps trash in a line. One thing you might check is whether your fuel tank is adequately vented. Often, the fuel cap has an integral vent so air can fill the void as fuel is consumed. If the vent is plugged, the symptoms are similar to what you describe.
A good way to check is to see if you get a sucking sound when you loosen the fuel cap after the engine dies.
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On Sun, 2 May 2004 09:29:41 -0400, "Kyle Boatright"

I checked the fuel flow from the tank through the fuel line. It seems okay there. The idea about the vent may be the answer. The cap that I have doesnt have a hole in it, but the rubber seal on the inside of the cap has a couple of groove in it that are probably intended to be vents. The only problem is they are far too shallow. I think when I tighten the cap down too tight I am closing off the venting. I cut two grooves a little larger and tried it again today. Now everything seems to run fine.
Another poster had a similar problem and suggested cleaning the bowl under the primer. I haven't done this yet, but it couldn't hurt.
Thanks for the help. Andre

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Hi Andre, I had a similar problem with mine yesterday. I haven't cleaned my carb for a long time nor emptied out my gas tank out at the end of the season as you are supposed to. I opened up the small container under the primer button (let the gas dribble out), and inside I found a load of slimy gucky bits. Cleaned it out and after also cleaning the air filter it fired up and is running great! I also changed the oil while I was on a roll. Rob
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Thanks Rob,
I may have solved the problem with venting in the gas cap. I will do what you suggest as well. It sure can't hurt. The gas does seem to be getting through now, but I suppose debris could be moving around and clogging the line intermittantly.
Andre
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Dies after half an hour sounds like one of several things.
Might be valve clearance, which is hard to explain over the net.
Might be a bad gasket between the carb and the engine -- leakign and letting in air.
Gascap vent clogged is very possible. Try the new filler cap.
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On Tue, 4 May 2004 09:21:30 -0400, "Stormin Mormon"

It seems like it's running fine now. I checked the fuel line to make sure that it wasn't clogged anywhere. I discovered that the gas cap wasn't venting at all do to a faulty rubber seal. There is no hole in the cap, but the rubber seal looks like it is designed to vent. I just cut the vent slot a little bigger and it seems okay now. I'll know more in a couple of days, when I have to cut the grass again.
Thanks, Andre

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