Lately in the warmer weather (or when i drive it far enough to get the motor really warm), i've been having a weird carburetor problem. Runs great, then i stop it, get out, go into the store, and come back out...and it's flooded! Not really bad, but enough to where i have to get out and blow down the carb for a minute or two to get it to where i can start it. Now usually it would be easy enough with a stuck float valve or something, but i know that it's not overflowing in that manner (i have clear fuel level sights and the level never changes). I've tried to catch it doing anything in the way of pouring gas down the carb and i can see nothing above the butterflies. Has this ever happened to anyone before? The carburetor is a demon...really the same as a holley. Thanks!
Can you tell if the problem is on the primary or secondary side? The secondarys get a small amount of fuel even at idle. Is any gas dripping from the shooters or boosters?
I would be willing to bet that the float level is a bit too high. Either that, or the idle mixture is a bit on the fat side, both will do the same thing. Good luck
A common problem with these cars. After the engine stops the temperature rises and causes the fuel in the carb bowl to boil. This forces fuel out the boosters. About the only way to affect this is to install an electric fan to keep air flowing over the engine for awhile after shut down and insulate the fuel line. Remember that exhaust gas is present at the base plate of the EGR valve and adds heat in addition to the normal engine temperature. The engine bays are very tight due to the solid panels from the front past the spring towers to the fire wall. This allows the heat to stay much longer
A good way to test Kens theroy is to open the hood as soon as you shut the car off and see if that helps.
yes, Ken's theory is possible, very possible. It's more prevalent on Carter/Weber/Edelbrock carbs though, I've never had any of my holleys boil gas. That doesnt mean it's not possible though. Had a '83 Ford truck that did exactly that....with an Edelbrock 750 on top of a 466. Changed to a holley, problem stopped---oh and picked up about 50 HP too
Heh, it seems like it doesn't do it when i open the hood, so i suppose it's possible. It doesn't do it all the time, and sometimes it's hard for me to tell if it's cold and needs me to pump more gas in or if it's flooded and putting more gas in will make the problem worse. What's confusing to me though is that with the clear float level sights it doesn't seem like the float level ever changes, i mean between when it's flooded and when it's running and all, it doesn't seem like it ever fluctuates. I also can't tell if it's on the primary or secondary side, there's never any fuel on the boosters. I will check the idle mixture screws...the demons have four corner idle and i have my secondaries closed almost completely but the idle mixture screw is open about 1/2 turn (just to keep some gas flowing through so it doesn't get old). Thanks for all the suggestions! By the way, i've seen (mostly at shows) some of the holleys have a big metal plate that is supposed to shield the carb from heat, do those things work at all? I was also thinking about a phenolic spacer, wish i had kept my old one.
Carb and EGR My problem with the carb was the worn out gasket between carb and EGR plate. Once that was replaced the carb worked fine until my points gave me trouble. Then I replaced those with a Pertronix. There's always something raising its ugly head.
Quite often a flooding condition after the car is parked can be traced back to a fuel pump return problem. If the pump doesn't bleed the pressure back into the tank as it was designed to do, the pressure can force its way past the needle and seat and trickle down into the engine. I have often found that you can pull the carb after it sits hot for a while and see if there is gas puddled in the intake. Usually, replaing the fuel pump will fix this. Just a thought.
Put in a new (or your old) phenolic spacer. This keeps the carb from becoming a "heat sink" for the engine and boiling the fuel in the bowls. Worked like a charm on Pegasus! Tracy
I have this problem where it becomes flooded while sitting over night or for several hours. Is this indicative of a larger problem? Maybe the fuel pump idea?... Fuel pump has less than 2,000 miles on it Gasket is fine, carb is new edelbrock 1406, No vac leaks, and if it were a heat/boiling problem I would think it would be a problem every time I went into a store or something.
Nope. It's mechanical. The problem started all of a sudden a couple of months ago. One guy said it was probably the winter blend of gas.... but I don't feel that's it.
How are you confirming that it's flooded. Wet plugs?.. or you're having to hold it down to the floor before it starts with a puff of unburnt fuel?
I was having to hold it down to the floor to start it, and then it would start all crazy-like. If I take the air cleaner off and prop the flap on the carb open for a half hour or so before, it starts up so much easier.
Does sound like it's flooded. Couple of things to consider. First rule is to diagnose where the excess fuel is coming from and exactly when it is happening. My guess is that the fuel pump is not allowing ANY drain-back and pressure is creeping up slightly as the engine heat soaks the fully fueled lines/carb. This often creates "fuel swell"(because fuel density changes with temperature) resulting in slight spill-over out through the boosters. Which can be witnessed as occasional drips, sometimes "smoky" looking on hot carbs as the fuel partially emulsifies when it hits the hot butterflies, and also as wet butterflies. Excessive heat soak occurrence over time also eventually causes the oil to become "gassy" smelling and partially ruins its protective qualities. Easy to smell the really bad ones as they tend to happen quickly and cause hard starting in the shorter terms.. not so much the lighter/longer occurring ones that cause later hard starts. I would suggest this troubleshooting protocol. Remove air cleaner, close the hood and idle the car slightly longer than usual to let everything get good and hot. Shut the car off and let it heat soak for about 5 minutes. Open the hood to see if you can see any of the above mentioned drips/wet butterflies. If not, keep the heat in by closing the hood asap and let it heat soak for another 5 minutes or so. Quickly re-inspect and repeat as necessary. The hotter the weather.. the better the chance to make it act up while you're looking for it. Murphy's law can be a major PITA sometimes. If this turns out to be the issue?.. double check/replace the needle and seat to assure proper seating/sealing.. install a heat resistant gasket under the carb(this is a biggy).. and insulate the lines running anywhere near heat sources starting with the hottest area's first. This will also allow greater consistency in fuel temps no matter the weather and may even give slight power bumps as an added bonus if things were really getting hot to begin with. The greater the fuel temp drop.. the better. Good luck with it all.
