Crankcasepulse pressure

[spudnut]

Working on a 1980 Trailfire 440, having trouble getting it to pump fuel. Does anyone know what the pressure/vacuum pressure out of the crankcase line should be? I have a gauge and it is reading about +/- 5psi. That does not seem enough to me.

[JDT]

The pulse from the crankcase to the fuel pump goes from Vac to pressure as fast as the engine rpm is. You will not see this on a actually reading on a guage.
With that said if you see the neddle bouncing above and below zero than it should be ok.

[spudnut]

Yea, it bounce back and forth. So it must be the pump, the diaphram looks ok to me, but maybe it is bad, any other posibilities?

[spudnut]

I got it working, don't ask me how. I replaced all the fuel and pulse lines, and pump diaphram and it still would not pump fuel by pulling the starter rope. Took the "out" line off the pump and used it to fill the carb bowl. Started it up and let it run, reconnected the fuel line to the pump and it has been running ever since. Maybe it just needed primed from sitting all off season.