Nah tank should hold a few PSI (3-4) of pressure - tank vent will hold a wee bit of pressure its to prevent fuel from getting out, and main purpose is to allow air in and prevent vapor lock. I'd suggest pour about a teaspoon of gas into the spark plug hole and put plug back in, see if it will fire on that gas, if it does then likely a fuel supply problem - if not, could be a valve hanging open (which might explain why the excess clearance if it was)bill18163 wrote:Well I did have to adjust the valves. The intake was way off. It still will not start. It's not getting any fuel. I can pull on the start cord many times and then go check the plug and it's dry as a bone. Compression seems Ok. My readings are a little iffy because I have to use an old press in style gage. I don't have a screw in gage. Looks to be in the 80's and the spec for this engine is 100/87. It's getting spark for what that's worth. I took the carb apart and except for a small adjustment needed on the needle valve lever everything else looks OK. Very clean inside. One thing that bothers me and I can't make sense of is why would the fuel tank have pressure in it? When I was taking a carb hose off the other day fuel came squirting out full force from the hose port on top of the tank. I had to grab the fill cap and open it to balance out the pressure to stop the fuel from squirting out. What would cause the fuel tank to build up pressure? Now that I think of it as I write this post wouldn't the tank vent valve balance the pressure in the tank to agree with atmospheric pressure outside the tank? Isn't that what it's supposed to do? Is my problem as simple as a bad vent valve? Any comments or suggestions would be appreciated.
I would do the tach thing right now, and get your idle and high speed settings dialed in to factory spec - Idle setting is very important and if it is maybe a bit lean (and masked by a bit rich on the high speed side) it can be hard to start. So, I'd find out the factory specs for both idle and high speed , and follow procedure (with proper load applied - this may involve removing guard to allow a longer string, or shortening the string to a specific length) to set the idle mixture first to get it dialed in (basically turn in/out the idle stop to get specific RPM while adjusting idle mix, then do the "rich down") and then do your high speed mix adjustment, THEN see if it starts properly after a cool-down - those mixture adjustments can have a huge affect on startability.bill18163 wrote:I took the limiter caps off the adjustment screws when I rebuilt the carb and I actually think the machine is running too fast by the sound of it. If I ever get this problem solved I'll put my tachometer on it and make sure it's within specs but for the little amount of time I test run it I don't think I can hurt it. Further suggestions??
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