In other words, after the new or no-filter prime test and pump side inspection, if you have nothing definitive I'd just replace the whole carb. Given how much time and money you could spend trying to get it to work properly, and that small delivery galleries could remain restricted and it still won't run right even once the primer works, your best bet is then to replace the carb. And if you find gelled fuel, stop there, that's bad news. While this may be a learning experience, you have to consider WHY the primer quit to begin ually it's from stale fuel building up gum/varnish, or corrosion, both of which are from not using a fuel preservative. If so, then that would just leave the primer assy. Check the inlet needle valve to see if it can be opened freely by depressing the lever. If the screen and flap valves look ok, pull the metering chamber cover with the primer over it. If you ever pull one out, you'll need a drift punch or similar tool to re-insert properly. FYI rarely you'll have to take note that the screen inlet is reverse flow, and crap can be under the screen rather than on top. There's a screen in there, and 2 flap valves that would then need inspection. If it still doesn't prime with a new, or without a filter (can test w/o one to speed things up here), pull the pump chamber cover - the side opposite the primer. The fuel filter will need to be replaced no matter what, because if you end up replacing the carb., you should always replace the filter to protect that investment. Still, they have to be checked to be eliminated from suspicion. Usually when the conditions I mention above exist with regard to a restriction in the system, the primer won't prime and won't return either. fuel pump diaphragm check valve (flap valve) could also provide that symptom. Or just heavy corrosion in the carb.Ī bad carb. In most cases when a primer won't fill, there is crap in the fuel system - clogged filter in tank, clogged inlet screen in carb., or stuck inlet needle valve. Sometimes a primer won't fill, but the engine will still run ok - rare, but it happens. Clamping one line off at a time and pumping it does help tell you the condition of the primer check valves. If a carb.-mounted primer doesn't fill, it could be the primer plate is NG.Ĭlamping off both lines an pumping the primer isn't a test we use. When you pinch off the fuel lines and let up on the primer, on the return of the bulb is emptying what fuel it can from the metering is natural for it to return a couple-three times before it creates a partial vacuum. Yes, the little white thing hanging out in space is a tank vent - supposed to let air in, and not out. The primer isn't a primer at all, it is an air purge for the carburetor system.
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