Hi Guys,

I tried to rebuild my old Holley 850 DP.

The car fires up and idles, but is dumping a load of fuel beneath the throttle blades. Raw fuel is coming out the exhaust, but interestingly only on the passenger side.

Any ideas what I might have screwed up?

Thanks.

Greg

might be a piece of dirt lodged in the needle/seat. sometimes even with a good cleaning of the carb itself, the dead air space created when you open the line, then when done the fuel rushing to take up that space will dislodge a minute piece of debris in the fuel line/pump.

So a needle/seat/float problem would be the likely cause, right?

I read overpressurization could also be a cause, but it's just got a mechanical fuel pump, and my 750 carb seems to be okay.

I would think, but not sure why its only on the one side (& my Holly exp is real limited). I would go ahead & open it up & go thru everything.

I am confused on why only one side.
most things would affect both.
the needle/seat/float affects one whole bowl not just one just/side.

the only other problem I have had is when I did the rebuild it was with a generic kit and I put in the wrong gasket for the idle circuit.

but in my case it would not idle.

unless you are parked on a slant.

in which case I might just re check the float level as a whole.

with the sight hole open, are you getting fuel pouring out?

Don't forget the power valve(s); a ruptured diaphragm or leaky gasket will dump fuel below the throttle blades.

You can eliminate a few items by pinching off the fuel line. When the fuel supply is cut off and the flooding stops, then some items like dirt between the needle and seat or improperly adjusted floats will be the problem. Because once the fuel flow is stopped to the carb, then the overflow stops.

But items like a blown power valve or accel pump circuit problem can still cause flooding as long as there is enough fuel in the bowl.

Thanks everyone, I will check these things out.

Greg