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73-87 Chevy _ GMC Trucks => Fuel Systems and Drivability => Topic started by: ken4444 on November 16, 2018, 12:24:55 pm
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I'm trying to remove the fuel line to the front bowl of the carburetor but the metal tube is twisting. I'm using a line wrench on the #1 nut below and pushing it toward the firewall, which is turning the nut left which should loosen it. I was able to loosen the #2 nut a but but I don't know if that's correct. How can I remove this fitting without breaking the tube? (This is a Quickfuel carb but I have no idea which model. I called Holley/Quickfuel but they were not able to figure it out after a few minutes.)
(https://i.imgur.com/g17PSju.jpg)
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You have to hold the #2 while loosening the #1. I know this sounds bad but that is how it is done....
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Agreed.
Typically, twisting of the tube occurs when the carburetor fuel inlet nut is not properly supported with a backup wrench. Spray around the tube where it enters the line nut using some lightweight penetrating oil (PB Blaster, Sili-Kroil, Liquid Wrench, WD-40, etc). Support the carburetor fuel inlet nut (#2) with an appropriately sized open-end wrench to hold it stationary while loosening the line nut (#1) using a 6-point flare-nut wrench.
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Thanks for the replies! I will continue to hold #2 while turning #1. I'll add some liquid wrench and let it soak in.
Here's the backstory: This all started when the truck would randomly not start. I used an inline spark tester and was getting good and consistent power to at least one spark plug, so I ruled out ignition system problems. I pulled the rubber fuel line that feeds the carb and it had plenty of fuel spray out. Taking a tip from Roadkill, if I tapped on the carb with a rubber hammer, the truck would start. This lead me to think the float was sticking. I pulled out the needle and seat assembly and it looked OK. I cleaned with carb cleaner but the problem still remained. So now I want to check the float assembly to see what it's doing.
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Okay, I got the fuel line off OK. I was 90% of the way there already but I had to reposition the wrenches to get more leverage and the thing unscrewed without too much effort. The float looked fine but I sprayed out the whole bowl assembly anyhow, and re-sprayed the needle and seat assembly.
I got it back together and it wasn't idling right. Go figure.
I found this video that covers some tuning basics of this kind of carb: https://www.youtube.com/watch?v=70hhpX2tfsE (https://www.youtube.com/watch?v=70hhpX2tfsE) . I had to adjust the front idle mixture screws. They were out about 1/2 turn and I brought them out to 1 1/2 turns. The bowl level was high, so I had to screw the needle/seat assembly down a few turns. The accelerator pump and pump arm clearance was wrong, which makes sense because I thought I had to remove that screw to get the front bowl off. According to this video, there's supposed to be .0014 clearance here which seems pretty picky. I was able to get it somewhere in there.
During all of the adjustments I didn't have any fuel delivery problems, but it needs to sit overnight and I'll know if it's sticking again or not. I also worry that I'm going to need to rebuild the carburetor because I suspect the engine may still not be running right after a test drive. Who knows if there's a vacuum leak somewhere.