QuestionBriggs & Stratton 190416 Type 2996 8.5HP horizontal shaft (Snowblower). Very difficult to start and doesn't want to keep running. Spark looks good and armature gap is within spec. The previous owner rebuilt the carb and replaced the fuel filter - along with the electric starter which burned out from trying to start the dang motor. He got fed up with it and gave it to me. I disassembled the carb and checked the rebuild - everything looked good. I still soaked the parts in carb cleaner and blew out all of the passages - I also rechecked the float level. Motor still did not want to start and stay running. By futzing with the choke, it is possible to get it to pop and run for a few moments. Sometimes long enough to try adjusting the needles, but then it will quickly die I checked the leak-down and it seemed a little low at about 85%. I opened the motor up and everything looked relatively clean. Valve lash was on the loose side of the spec. I cleaned everything and re-lapped the valves and seat. Valve lash is now of the tight side of the spec. There was a little bit of scoring on the cylinder walls, but nothing alarming. I think I'm confident that it is not the motor itself which is causing the problems. I checked the flywheel key and it is not sheared so timing should be correct. My last guess is to throw a new magneto at it, but the spark does look good. And/or possibly replace the carb yet everything inside it looks nice and clean. I've tried different gas. I did get it running once where it stayed running and I was able to use it for about 20 mins. The idle oscillated around and it had an occasional backfire in the exhaust (too much fuel?), but it did run and seemed to have plenty of power. When trying to start it with the choke closed, some gas will drip out of the intake opening (maybe the fuel is not atomizing with the incoming air?). It seems to pop best when you hold the choke closed for several revolutions and then open the choke up. Starting fluid does not seem to help. I'm at a loss and can't thing of anything else to do but to throw a new carb and/or magneto at it. Help!?
AnswerDave
I will give you some ideas that you may try some may seem simple,usually that's the answer something easy.Sounds like you went through all the steps,I feel positive it is a fuel problem and a dry plug.Replace the spark plug and try closing the gap to about 026-028
Check your gas cap. The gas cap is a source of ventilation for the fuel tank. If your gas cap is clogged it will make your fuel tank vapor lock, and you will have no gas flow. To check and see if the gas cap is bad, loosen the gas cap and see if it will run longer than before you loosened the gas cap. If it continues running, you need to replace the cap, if it does not continue running check further.
Do you have a gas filter? If so is it clear? If not, replace it.
The float controls the gas level in the carburetor. If any of these signs occur, the carburetor is overflowing out of your air filter or out of your primer. If you have gas in your oil, you have carburetor problems. NOTE: Drain the oil if there is gas in it, if you don't it can be dangerous. You need to check the needle & seat to see if it has trash or is bad. Is your float bad? To check the float pull the pin that holds your float in place, shake the float and if there is fluid inside of the float, replace it. Don't forget to set the float level.
Carburetors with primers represent a large majority of lawnmower and small engines today. They have primers to push or force air in the carburetor and in turn force gas through the center jet to make starting easier. Then look to see if the primer is pumping gas in to the engine.
Things to check for if the primer is not working. This applies to several different types of engines. Check for holes or tears if you have a carburetor that has a diaphragm. (A diaphragm is a gas pump located in carburetors that have the gas tank and carburetors assembled together.) Replace the diaphragm if the diaphragm has a hole or has hardened or slightly slid over to one side, or if the engine will not run correctly and is skipping, not priming, or will not run at all. If you have a float type carburetor, the bowl gasket may not be sealed properly and air will leak past the bowl gasket and will not prime. If you have a air assembly primer box where the air filter box is connected to carburetor, your gasket may not be sealing correctly. If there is a tear or a hole in the gasket, air will leak past it and will not force air in the carburetor which will not force gas through the center jet. Also your air assembly box may have a crack and will be warped because it was over tightened. If so, replace it.
Some models have chokes. Chokes are used to draw gas through the center jet to run. If the choke is not working properly and it is not closing all the way the engine cannot draw gas through the center jet and will not crank.
The throttle cable is what operates the choke on some models and the primer on some others, but it works the speed of the engine. To adjust the throttle that works the choke you need to loosen the throttle and open the throttle all the way, then push it until the choke is closed all the way. To adjust a "speed only" open the throttle all the way and make sure that the engine speed will be all the way open and then tighten the cable back up on the engine. Make sure if you have a kill switch on the throttle cable, that it works when you lower the speed all the way. If not, adjust again. Carburetors: Carburetors are the cause of 99% of all small engine problems. Carburetors are the easiest thing to repair on small engines.
