don't feel lonesome afriend of mine got gave to him a 21" selfpropelled,electric start he said that after w while of mowing it would die gas would come out of the carb. found part # ordered one from ebay put it on today start die start die,took it off clened up the old one mowed about 30feet started spitting spurtting then dead it will not hit a lick primer bulb is working insted of shooting a mist into the carb it spewes out of a brass pipe in the carb. could almost run back out spraye carb cleaner in it won't hit a lick.going to try one more carb. if it don't work to the dumpster it goes i even did a compression check 100psi that's good enough to run on.seems to me like troy bilt had a bunch of 2nds not up to standard quality passed them of to lowes and other places got a lowes hot line going to call tommorrow see what they say.not mine they may not talk to mei don't know when engine cos. quit rating engines in hp this is 7.00hp bought a new bolens it's ccs.

Try replacing the diaphragm. 3.75 Briggs carb rebuild This is an easy DIY job to replace the diaphragm of the carburetor. A damaged diaphragm will cause engine surging, hard starting, and erratic high speed operation. You may also notice that the primer bulb isnt working properly. This is an overview of the carburetor and these types of carb-over-tank are typical of small Briggs engines. Note the two governor springs. The carb/tank assembly is held in place by a ½" bolt to the left of the carb and a 3/8" bolt on the engine head to the right. Remove both bolts and pull the tank straight out with a rocking motion. If possible, the carb/tank assembly should be blown off with compressed air and all loose dirt removed. Use the proper safety equipment, especially safety glasses, before using any compressed air in any of the steps below. In the highlighted area you will see the governor linkage still in the throttle plate of the carburetor. You will have to gently separate the carb/tank assembly from the linkage. It is a Z type linkage. It is not necessary to remove the springs or the other end of the linkage, from the governor. Note that on the rear of the carburetor is found a white plastic ring and O ring. Sometimes these remain on the tube of the engine housing. If so, place them back into the carburetor body, as shown, before reinstalling the carb/tank to the engine. Note the raised area of the diaphragm. This is caused by age, but more often, by ethanol fuels, which damage the diaphragms. A damaged diaphragm will cause engine surging, hard starting, and erratic high speed operation. You may also notice that the primer bulb isnÂt working properly. Shown here are the dip tube, which brings up gas from the tank, in the bottom left corner. Just behind that and partially obscured, is the orifice that compressed air can be used to clear the dip tube of debris. It also leads to the primer bulb, so any air must be low pressure and the primer bulb must be held in the depressed position to prevent it from blowing out. In the center top, youÂll notice the jet, surrounded by a wire mesh filter. In the bottom right is a spring. Be careful to not lose the spring or forget to install it during reassembly. Remove the old gasket and diaphragm combo from the carb body. Install a new gasket/diaphragm on the smooth surface of the tank. I always blow out the tank with compressed air to remove dirt and any water. Be aware that there may also be old gas in the tank. I always empty the tank and let it sit in the sun until all the gasoline evaporates before applying compressed air. Align the carb and lower it down on top of the gasket, trying to keep the five screw holes in the gaskets aligned. Insert the screws and partially tighten them and install all five screws. Tighten each screw until it gently bottoms out. Then turn each screw another quarter turn. It is not necessary to use more than a few inch pounds of torque on these screws. Reinstall in reverse order. When installing, be sure to engage the breather tube with the rubber piece on the carburetor.

"Grinding", that might be a bit tight (by my definition of "grindingly tight"). There really should not be any "tension" on the feeler gauge at all. What we are trying to establish is the proper amount of CLEARANCE or empty space between the end of the valve and the rocker arm. You really want the feeler gauge blade to slide very easily when it is withdrawn from the rocker/valve juncture, and it should slide back into the same without your having to force it or manually push the valve open to get it back into the space. Or in other words, you want the open space to be exactly the same amount as the thickness of the feeler gauge blade. If you can actually feel the drag or resistance against the blade, you are too tight (too little gap). Do this: Turn the engine while watching the valve action. When you turn the engine so that the intake valve has been pushed down as far as it will go, measure the height of the valve spring from the cylinder head up to the top of the valve spring washer (use a small pocket ruler). Carefully read the dimension and record the value. Next, turn the engine until you see the exhaust valve move down as far as it will go. Measure the same way as before and compare the 2 values. The distance should be identical (or within 1/32" inch) for both valves. If you measure a difference of 1/8" or so between the 2 values, the camshaft is worn out (a possibility on 31 series engines).

Receive all my parts finally, and had a warm day yesterday. After looking at the gasket surface of the head closer, there was no doubt that I had a leaking head gasket. I taped the corners of sheets of sandpaper onto a large piece of glass and smoothed the gasket surface area of the head. Started with 150 grit and worked my way up. This took some time. I was surprised how warped/uneven the gasket surface of the head appeared to be. I checked that old coil again and the readings were still off so I left the new one on the mower. The old one produced a spark, but meter showed bad readings as noted before. Torqued the head to spec and put her all back together. Started on 3rd pull and purrs like a kitten! Note to others that my head gasket was leaking on the bottom, and it was almost impossible to detect without removing the muffler and/or the head. If I had it to do over, I would have, if necessary, removed the muffler and sprayed carb cleaner along entire the gasket surface with the engine running before removing the head. However, I waited too long and couldn't even get the engine started. In my case, it worked out well because the gasket was definately leaking. Do yourselves a favor and check compression in the early stages of repair before throwing parts at one like I did. The low compression reading, along with Tomplum, got me on the right track. Thanks for the good advice. This site is awesome!