Flooding at idle but not float level problem
07-01-2017, 02:12 PM
#1
Melting Slicks
Thread Starter
Flooding at idle but not float level problem
BG Demon 750 idling rich and stalling but float levels are fine. The one telltale symptom is that gas spits out of primary vent tube and the venturis appear wet.
Can debris foul a power valve and keep it from fully closing? It was flooding and stalling yesterday with a fouled needle valve so I changed the fuel filter, cleaned carb plus replaced needle valve and power valve. There was debris in the float bowl which is why I changed the filter back at the tank and did my best to flush out the fuel line from the filter to the carbs but there's only so much one can do.
Can debris foul a power valve and keep it from fully closing? It was flooding and stalling yesterday with a fouled needle valve so I changed the fuel filter, cleaned carb plus replaced needle valve and power valve. There was debris in the float bowl which is why I changed the filter back at the tank and did my best to flush out the fuel line from the filter to the carbs but there's only so much one can do.
07-01-2017, 03:15 PM
#3
did you clean/blow out all the passages in the metering block?
did you clean/blow out the air vents in the main body?
did you clean/blow out the air vents in the main body?
07-01-2017, 05:15 PM
#5
Melting Slicks
BG Demon 750 idling rich and stalling but float levels are fine. The one telltale symptom is that gas spits out of primary vent tube and the venturis appear wet.
Can debris foul a power valve and keep it from fully closing? It was flooding and stalling yesterday with a fouled needle valve so I changed the fuel filter, cleaned carb plus replaced needle valve and power valve. There was debris in the float bowl which is why I changed the filter back at the tank and did my best to flush out the fuel line from the filter to the carbs but there's only so much one can do.
Can debris foul a power valve and keep it from fully closing? It was flooding and stalling yesterday with a fouled needle valve so I changed the fuel filter, cleaned carb plus replaced needle valve and power valve. There was debris in the float bowl which is why I changed the filter back at the tank and did my best to flush out the fuel line from the filter to the carbs but there's only so much one can do.
07-01-2017, 06:08 PM
#7
Would it be correct to assume fuel is spitting out the nozzles into the venturi also? try to lower the float level one turn clockwise and see if this stops the boiling outside the bowls.
Last edited by tbarb; 07-01-2017 at 06:11 PM.
07-01-2017, 06:25 PM
#8
Melting Slicks
Thread Starter
I don't see it 'spitting' out the nozzles but that's not to say it's not weeping out. I've lowered the float level to the bottom of the sight glass which is a larger opening than standard Holley. Do you firmly believe it's a fuel boiling issue? I'll have to go have a look now that it's cooled down and see if it still does it.
07-01-2017, 07:09 PM
#9
If it does not spit fuel when the engine is started cold and only does when good and hot then I believe it boiling fuel.
If that's the case lower the fuel level a turn and see if it makes a difference. You also need to try and find out if there are things that will allow the engine to run cooler like manifold vacuum advance, wire heat riser open, a shield under the carburetor that extends out to shield the float bowl from heat soak coming from the intake manifold.
The ethonal fuel is the problem with it's low boiling point.
If that's the case lower the fuel level a turn and see if it makes a difference. You also need to try and find out if there are things that will allow the engine to run cooler like manifold vacuum advance, wire heat riser open, a shield under the carburetor that extends out to shield the float bowl from heat soak coming from the intake manifold.
The ethonal fuel is the problem with it's low boiling point.
07-01-2017, 07:45 PM
#10
Melting Slicks
Thread Starter
If it does not spit fuel when the engine is started cold and only does when good and hot then I believe it boiling fuel.
If that's the case lower the fuel level a turn and see if it makes a difference. You also need to try and find out if there are things that will allow the engine to run cooler like manifold vacuum advance, wire heat riser open, a shield under the carburetor that extends out to shield the float bowl from heat soak coming from the intake manifold.
The ethanol fuel is the problem with it's low boiling point.
If that's the case lower the fuel level a turn and see if it makes a difference. You also need to try and find out if there are things that will allow the engine to run cooler like manifold vacuum advance, wire heat riser open, a shield under the carburetor that extends out to shield the float bowl from heat soak coming from the intake manifold.
The ethanol fuel is the problem with it's low boiling point.
I have headers so no heat riser and do run manifold vac advance, which only leaves adding a shield under the carb. I did add a 1/2 spacer previously because I was concerned about how close the high volume accel pump sat to the intake riser but apparently that wasn't enough.
Thanks for the tips.