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Posted by Sherman in Idaho [72.47.9.37] on Saturday, August 25, 2012 at 10:51:38 :
In Reply to: M-37 fuel supply problem..suggestions? posted by George in MI [174.124.174.241] on Saturday, August 25, 2012 at 10:36:38 :
Is there a bowl/filter on the fuel pump? Is there dirt on the screen of it? When fuel pumps fail, they don't necessarily put gas into the oil. Sometimes it comes out the "weep hole", and sometimes it doesn't come out anywhere, but the pump just doesn't pump. Dirt can get stuck in the check valves inside the fuel pump, in which case it won't pump but there won't be any leakage either. If the M37 is still stock, it has a filter inside the tank on the pickup, which can get clogged. If there is dirt in the tank which has clogged the pickup, a "field expedient" to get it back to the shop is to disconnect the fuel line at inlet to the pump, and blow hard into the line to blow any crud off the inlet in the tank. I have done this and had it work for a while. Eventually the crud will find its way back to the inlet and clog it again. If the fuel pump is put together with screws, it's easy enough to take it apart in the field and see if the check valves are okay or there's dirt stuck anywhere else in it. If cranking doesn't make any fuel come out of the pump, and you know there's 5 gal in the tank, it sure sounds like the pump is bad or the fuel system is clogged. I suppose it's possible that the pump arm that rides on the cam could be worn out or broken, but the only time I've seen that was on my motor that threw the #1 rod, which came down and destroyed the fuel pump lever arm.