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86 GMC 4x4 305edlebrock 1406Discovered that i had water in my gas tank. Ran through some Heet and couldn't get it to git rid of the water. I dropped the tank and drained and resealed my sending unit. Put fresh gas in it with some seafoam and couldn't get it to idle below 1500 rpm. Runs pretty smooth after 2000 rpm. Things I have Tried:-Replaced plugs-Checked for vacuum leaks-Drained carb and cleaned out-Replaced carb gasket-Put electric fuel pump on(buddy had one...still have mechanical to put back on)-Replaced fuel filterWhat to do next?
Best guess is crud in the idle passages came along with the water blocking idle passages and you must open the butterfly’s enough to bring the main system on line to add fuel to keep running.You can try to blow out the idle passages through the mixture passages with compressed air or carb cleaner if compressed air is not available.Unscrew the mix screws counting the turns and remove. Blow though the holes using all safety precautions. Watch for spraying fuel.Install the mix screws back where the we’re counting the turns.
Hi, Scritt had mentioned in his original post that he had drained and cleaned the carb. I am curious how the carb was cleaned after draining? At this point in the discussion I am inclined to agree that the idle circuit is clogged and that is the reason the set screw has to be turned in to bring airflow past the mains. Admittedly, I am not well versed in QJ carbs but have encountered this situation in other carbs.All the best,Tracey>>>>>>>>>>>>>>>>>.
I had a similar problem with high idle, but what I found was caused from ethanol sludge in the carburetor from sitting idle for several months. If you cleaned out the carburetor because of sludge, it's more than likely you need to overhaul your carburetor. I've total broke down my Edelbrock carburetor and found numerous passage inside the carburetor had been clogged up. After my carburetor overhaul, my idle speed was restored. You might it better route to invest in an new aftermarket or Edelbrock carburetor. If you have a Edelbrock carb; take pictures during the breakdown and when removing every part do not to forget to the fuel filter screens where the needles and seats are. When removing the primary metering jets at the bottom of each bowl, be careful not chip away the screw wall when removing passage screw by using a properly fitted screwdriver and even pressure. I used carburetor cleaner, air compressor, small brushes and wooden tooth picks to clean small jet holes. I was able to use the same gasket after cleaning every parts. Use a good work table with lots of containers to hold parts and don't loose those step-up piston springs because they're so thin and very hard to find if they roll away!! Good luck.
Quote from: Chuck Step-a-side on April 08, 2018, 12:20:01 PMI had a similar problem with high idle, but what I found was caused from ethanol sludge in the carburetor from sitting idle for several months. If you cleaned out the carburetor because of sludge, it's more than likely you need to overhaul your carburetor. I've total broke down my Edelbrock carburetor and found numerous passage inside the carburetor had been clogged up. After my carburetor overhaul, my idle speed was restored. You might it better route to invest in an new aftermarket or Edelbrock carburetor. If you have a Edelbrock carb; take pictures during the breakdown and when removing every part do not to forget to the fuel filter screens where the needles and seats are. When removing the primary metering jets at the bottom of each bowl, be careful not chip away the screw wall when removing passage screw by using a properly fitted screwdriver and even pressure. I used carburetor cleaner, air compressor, small brushes and wooden tooth picks to clean small jet holes. I was able to use the same gasket after cleaning every parts. Use a good work table with lots of containers to hold parts and don't loose those step-up piston springs because they're so thin and very hard to find if they roll away!! Good luck.Thanks for the info...Sent from my SM-G920V using Tapatalk