Jacobsen lawn queen fuel problems?

[Austen]

I have a late 1940's Jacobsen lawn queen two stroke mower that I'am fixing up. The carburator has just been cleaned and rebuilt and put back on. The mower starts and runs very well. For some reason now it will run for about 10 minutes just fine and then all of a sudden act like it is running out of fuel and then die. If you try and start it again it will start for a few seconds then die. There is plenty of fuel in the tank. If you let the mower sit for about a half an hour it will start right up and do the same thing. Someone told me that the gas cap vent whole could be pluged? If you have any suggestions please let me know. Thanks.

[MoRo]

Try taking the fuel cap off the tank and running it that way. Stuff a rag in the hole so as to keep debris out. That'd tell you if the plugged vent theory is correct.
~M~

[K D Redd]

The coil or condenser could be getting hot and you are losing ignition.

Kent

[Houston]

Richen the mixture, 1/4 turn ccw should be more than enough, see if it will continue running then. If it does, either you were running too lean, or you have a failing ignition system. Dang motors are picky about running too lean.

[Austen]

I know what you mean about the fuel mixture. When I first put fuel in it,it was to lean and wouldn't run so I had to drain it and make a new mixture for it. I've been told that the mixture is 16:1, 32:1 and 50:1. Which one is the correct one?

[Bill Sherlock]

Austen,

I don't have a Jacobson manual but most two cycle engines of that vintage used 16 to 1 gas to oil mixture as far as I know.

Running too lean wasn't a reference to the gas to oil mixture, it's referring to the amount of fuel being burned.

Bill

[Andrew Mackey]

Is your mower equipped with the fuel line that makes a 'U' bend between the tank and carb? It may be collapsed internally, and is not allowing fuel to pass thru fast enough to keep the fuel bowl full. Is there any rust in the tank? There is a very fine screen on the inlet valve, and it may be jambed with dirt and or rust. Check the tank for water, it will do the same thing! With the fuel cap on, pull the fuel hose off the carb, and let it run into a can. If fuel flow stops or slows, remove cap. If it runs full again, clear vent hole in cap and gasket. Check float level, and inlet to top of carb. If dirt is in inlet, again, make up for fuel bowl is slowed - clean out debris. OIl mix for the Lawn Queen - 16:1 SAE 30 NON Detergent, or a good 2 cycle OIL - not lubricant. The lubricants are cut with mineral oil, and are made for modern hardened engines. The Lawn Queen is a plain bearing engine, and needs oil.
Andrew

[Austen]

I put a brand new fuel valve and hose on it temporarily to see if it would run any different. I have two parts engines for it that have fuel valves and fuel lines that I'll put on it later.

[toolazy]

I encounter a similar problem before tearing down my engine. The piston was so gummed up it stick to the top of the head when hot!

I also found that the brass fitting on the tank was clogged from over the years. Maybe this is the same reason yours is cuttin out also?

That and I believe the condensor was going. Just didnt seem to have a nice thick blue spark.

[Austen]

Well I've figured out it's not the coil that's wrong with it. The needle valve just doesn't seet proporly and when you put the needle back in, it just doesn't stay there it falls right out. We made an adjustment to it, but when I tried to start it, that's when the spring inside the recoil broke, so I'll have to wait until I get my new one I got off Ebay in the mail. Hope it starts!