View Full Version : Small Engine Problem

Walt B
Jun 9th 2012, 11:51 AM
I've got a 344cc, 12.5hp, manual start Briggs and Stratton engine that powers a shredder. The last couple of times I went to start it, the rope wouldn't release.

I removed the spark plug, cranked, and gas came out of the plug chamber. After a few cranks, then spraying starter fluid in the chamber, blowing it out with an air gun, and installing the cleaned spark plug, the beast started up, ran fine and started fine the rest of the day.

After letting it sit for a week, same thing happened with the same remedy. Today I just grabbed ahold of the rope as I walked by and the same thing. :???: It's going to get old going through this routine every time I'm going to shred.

I have a walk behind shredder with the same engine and it's fine. I'm greatful for any suggestions and how to fix this beast. Thanks,


Jun 9th 2012, 12:10 PM
I have a similar Briggs that did the same thing. In my case it was the carburetor inlet valve not shutting off and the fuel was gravity flowing from the tank and hydrolocking the cylinder. Todays fuels seem to be much worse for creating crud and attacking fuel lines of older equipment. Usually taking apart and cleaning the needle valve and seat does the trick. It can be a dangerous condition for fire.

Jun 9th 2012, 12:36 PM
I agree with Crofter, gas is flowing past the carb into the engine when it's not running. You can get a rebuild kit for the carb or depending on the condition of the gaskets you may be able to take it apart and blow it out. A quick fix is to put a brass shutoff valve on the gas line until you've had a chance to make the repair.

Jun 9th 2012, 02:29 PM
I agree with the above, but will add this.

Methanol will eat the seals in the carb, so always buy pure gas only, not the 10% meth. All your equip. will run much better and quit locking up.

Jun 9th 2012, 03:01 PM
The premium gasolines are supposed to have better stabilizers in them too. I have an old lawn tractor on which the fuel tank is actually disolving and going gooey with the alcohol content or some of the compounds they now use for octane boost. Springtime carburetor problems where gas has been left in are so bad that some shops are investing in ultrasonic cleaners that supposedly do the job without pulling the carbs apart. Of course lots of the new homeowner lawn and garden stuff is virtually unserviceable anyway and not made to be taken apart.

Jun 9th 2012, 05:08 PM
I agree with all of the above. A valve in the fuel line will work wonders on equipment that is hauled around while not running. When the float gets to bouncing around it is opening and closing the inlet valve all the while filling the cylinder and crankcase full of gas. You need to check your oil to make sure it is not diluted with gas.

Walt B
Jun 9th 2012, 07:19 PM
Thanks all for the suggestions. I think the fuel valve is going to be "insurance" for all the implements of destruction we have around here. The Honda mower came with a shut off, but it's the only one.

I'll let you know how everything comes out...kind of like "Car Talk" checking to see if their diagnosis was correct.


Jun 9th 2012, 10:19 PM
I run 100% gasoline in all my small engines. Here's a site that has pure gas locations listed (there are probably more, but this lists a lot of them):

pure gas (http://pure-gas.org/)

Jul 3rd 2012, 09:21 AM
Check your float, just had a similar problem with my shredder. Got the float positioned correctly, fresh unleaded gas and problem solved. Hope this helps. Tom