Hi,

We've been having an issue with my son's 78 Delta (350R 4bbl motor).

While it runs fine, if it sits a while (even just overnight) it is starved for fuel when you try to start it the next day. You have to crank it long enough to get fuel back to the carb and it starts right up.

No signs of any external leakage. I started wondering about the fuel pump. I know it has an extra vent line on it and I wondered if a check valve ir sometning in the fuel pump is letting gas drain back to to the tank. I replaced the fuel filter in the carb and that made no difference. I was thinking that some of those filters had a check valve in them.

Any ideas?

Thanks!

 

it sounds like one of two things:
fuel is percolating out of the float bowl, or,
the secondary well plugs are leaking.

is the efe system functioning properly? this will cause percolation if it's not.
the efe(early fuel evaporation) system has a valve in the driver's side exhaust manifold that closes after cold startup. it redirects hot exhaust through the intake manifold, under the carb; to improve cold engine operation. the efe valve should open when the motor gets warmed up. it is controlled by a thermostatic vacuum switch. mounted into the intake manifold, that does fail due to wear. malfunctioning also could be caused by incorrect vacuum hose routing in the efe system.


bill