Re: Fuel In Carbs But Not Into Pistons
Hi, Have A 1972 800 Thunderbolt Ignition Just Put A New Trigger In The Distributor Got Spark To All Of The Plugs But No Fuel To The Pistons Have Fuel In Carbs And Thats As Far As It Goes.any Help Would Be Great. Bob
Obviously you have to make sure all the jets are not plugged in the carbs, and I assume you've done that. With the cowling off, hold your hand over one of the carbs and crank the engine. It should solidly suck your hand onto the carb intake. If you get vacuum on one carb and not the other, or none on both, and all you feel is a sort of pulsating instead of solid vacuum, you got a broken reed block.
It's unusual to break both side of the reed block at once, so a L4 Merc will usually run on either the upper or lower pair of cylinders with a broken reed assembly. But I have seen a few engines where a chunk broke out of the reed assembly, got caught by the crank counterweight and broke both sides of the reed assembly, in which case none of them will fire.
If you have to put in a new reed block, when you got the crankcase split make sure to carefully check inside and find all the broken pieces. There's not much room between the crank counterweights and cases, and if there's a piece left floating around in there you could end up with a hole in your crankcase if it got wedged between a crank counterweight and the case.
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Chris