620connor Posted March 5, 2015 Report Share Posted March 5, 2015 Hey guys, i have a problem with my carb. I just purchased a new 32/36 genuine weber (made in spain) and after i installed it on my truck, i started it up and set the idle A/F ratio and she was idling as smooth as glass. The next day i was driving it and all of a sudden the idle dropped all by itself and i could barley keep it running. I drove it home and i adjusted the idle A/F ratio, and i had to back the screw out 2 full revolutions to get it to idle good again. So i drove it and it seemed fine. Then 2 days later the idle suddenly dropped all by itself again and i could barley keep it running to get it home. Then i had to adjust the idle A/F ratio screw 2 full turns back in to where i had it set before to get it to idle smooth again. I've never heard of a carb doing this before, could anyone give me some advice on what is wrong? Or how to possibly fix this? My truck is a 74 620 with the L18 engine. Thank you. Quote Link to comment
harlow426@mail.com Posted March 5, 2015 Report Share Posted March 5, 2015 I'll bet butterflys are not closing intermittently. If partially open when setting a/f.....closed will act up. Polish edge of butterflys/venturi/throttle shaft/bushing with mothers alum polish after deburring with worn scotchbrite-400wet/dry(q-tips in dremel work good 2 polish shaft bushing). Clean all polish up...use blue paper towels/qtips w/ carb/choke till no residue. Shy away from adding spring tension to keep em closed...accelerates shaft/bush wear. use good anti seize compound(sparkly stuff) when assembling. I have one fuel filter @ gas tank...one @ firewall...one between pump/carb. Dirt will taint a new carb. Wouldn't trust a new one out of the box till I verified clean inside. Dirt is the enemy.....ethanol dirts' close cousin. Quote Link to comment
dr.feltersnatch Posted March 5, 2015 Report Share Posted March 5, 2015 Also check real good for vacuum leaks Quote Link to comment
datzenmike Posted March 5, 2015 Report Share Posted March 5, 2015 Adapter loose? Did you use some kind of thread locker on it? New fuel filter? Quote Link to comment
banzai510(hainz) Posted March 5, 2015 Report Share Posted March 5, 2015 idle jet got plugged up maybe? rust/dirt in tank. best also to pull the fuel fiter and cut it open. if really bad then ck the idle jet on side of carb and pull out and clean the jet. If filter is clean then its another issue Quote Link to comment
kelowg Posted March 5, 2015 Report Share Posted March 5, 2015 Crap in idle jet. Quote Link to comment
620connor Posted March 5, 2015 Author Report Share Posted March 5, 2015 Harlow426- Okay i'll try setting my idle low and readjusting the idle a/f, and check for burrs and polish. Dr.feltersnatch- I don't think i have any any vacuum leaks but i will double check, i locked everything down pretty tight. Datzenmike- I locked everything down super tight and used blue locktight. My fuel filter isn't new but it only has like 10k miles on it. Should i replace it? Banzai510- My fuel filter is clear, and there is debris in there for sure. If i shake it small black debris swirls around. Kelowg- I'll try cleaning the idle jet. Thanks for the help/advice everyone, i appreciate it alot. Quote Link to comment
dr.feltersnatch Posted March 5, 2015 Report Share Posted March 5, 2015 Yes replace the fuel filter. Cheap and easy. And I would check real well for vacuum leaks. Its also cheap and easy. Quote Link to comment
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