Flooded Combustion Chambers
Thread Starter
Intermediate
Joined: Sep 2000
Posts: 43
Likes: 3
From: Honolulu Hawaii
Flooded Combustion Chambers
Believe my engine has flooded to a point where I've got excessive fuel in combustion chambers. Plugs are wet with fuel, and when I hold a paper towel in front of spark plug hole with plug out and turn engine, the paper towel becomes totally saturated with fuel in about 10 seconds.
I pulled all 8 plugs, turned engine for about 5 seconds, then let car sit for a week. Put plugs back in, tried to start it, and the plugs were wet again within just a few minutes.
Running Q-jet on performer intake -- nothing fancy. Q-jet is stock, and idle screws are set to basic 4 half-turns out. New engine, so rings are probably pretty tight. Could the fuel be "puddling" in a chamber for that long?
How do I dry out the chambers? Is it smart/safe to turn the engine with all plugs out for more than a few seconds to help push gas out?
I pulled all 8 plugs, turned engine for about 5 seconds, then let car sit for a week. Put plugs back in, tried to start it, and the plugs were wet again within just a few minutes.
Running Q-jet on performer intake -- nothing fancy. Q-jet is stock, and idle screws are set to basic 4 half-turns out. New engine, so rings are probably pretty tight. Could the fuel be "puddling" in a chamber for that long?
How do I dry out the chambers? Is it smart/safe to turn the engine with all plugs out for more than a few seconds to help push gas out?
Drifting
Joined: Apr 2007
Posts: 1,970
Likes: 45
From: Cameron Park CA
You might have a stuck float, or the needle & seat may have a foreign object lodged in there preventing the valve from closing. I had a similar problem recently on my Holley 4150 which turned out to be a fuel logged plastic float which I replaced with a brass float.
You can take the top off the Q-Jet and inspect the float and float valve. There is a warning in the Overhaul Manual, "Care must be taken not to bend two small main well air bleed tubes protruding from air horn. These are permanently pressed int the casting. DO NOT REMOVE."
Be extremely careful and have a fire extinguisher nearby.
Good luck,
Pete
You can take the top off the Q-Jet and inspect the float and float valve. There is a warning in the Overhaul Manual, "Care must be taken not to bend two small main well air bleed tubes protruding from air horn. These are permanently pressed int the casting. DO NOT REMOVE."
Be extremely careful and have a fire extinguisher nearby.
Good luck,
Pete
Melting Slicks
Joined: Dec 2006
Posts: 2,669
Likes: 3
From: Kingston Ontario
As soon as you resolve the issue, change your oil. Anytime you flood the engine and fuel wash your cylinders you stand a good chance of introducing fuel to your oil system.
Are you sure you have ignition. Even with excessive fuel or a choke issue it should still at least attempt to start. That's where I would start.
Wow, you guys type faster than me, but I agree with you!!
Are you sure you have ignition. Even with excessive fuel or a choke issue it should still at least attempt to start. That's where I would start.
Wow, you guys type faster than me, but I agree with you!!
Last edited by dannyman; Jan 19, 2008 at 08:22 PM. Reason: wow....
Drifting
Joined: Oct 2007
Posts: 1,317
Likes: 22
From: Marina CA
Make sure you have spark and have fixed the cause of the flooding before running the engine. The well plugs on the Q-jet were known to leak,and you could also have a hung/stuck or sunk (gas filled) float. Turn the engine over to clear the cylinders (plugs out) then give each cylinder a shot of oil and turn it over with the plugs out before you start it. This will get oil between the rings and cylinder walls. You have gas washed the cylinder walls and have no oil film between the rings and cylinders and it's metal to metal contact.
Also make sure you change the oil/filter like the other forum members have advised you to do.
Also make sure you change the oil/filter like the other forum members have advised you to do.
Racer
Joined: Apr 2007
Posts: 361
Likes: 0
From: Sacramento (Citrus Heights) California
When my QJ was flooding last week (only tried starting twice with flooding) I went ahead and changed the oil. Just as a test to see how saturated the oil was, I set my pan in the middle of a parking lot and threw a match at it. It lit up straight away. ~8 quarts came out of that engine, so it doesn't take much.
Put the fire out with my handy-dandy ABC extinguisher, which is always handy when working on carbs or around fuel.
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