I have a problem with my David Brown 885 tractor. I am getting no power (for obviously good reasons), frequent backfires, and gas (liquid) occasionally coming out of the exhaust stack. Cylinder 1 and 3 spark plug are soaked with gas (cylinder 2 seems to run fine), and are most likely not firing and the oil in the crankcase is also full of gas. Looking down in the carb I can see large drops of fuel coming out of the main jet. It is dripping directly into the intake manifold - it does not appear to emulsify/vaporise. I took the carb apart and made sure all the jets were clear, ensured that the float needle was not sticking, verified that the float level was correct, verified the fuel pump pressure, ~2.5 psi, which is within spec. I also checked the economy device. Although the diaphragm appears to be ok, I cannot tell for sure. It there any easy way to verify it? Could this be the source of my problem? If so, where can I get a replacement? Or can it be repaired? Any other ideas? Any help would be greatly appreciated - I'm stumped! Thx.
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