Idle up vacuum and other vacuum mysteries
#22
Your welcome.
I noticed in that picture the "Idle Mixture Screw" is backed out quite a bit. It is the brass looking slotted thing to the lower left of that port in the air cleaner housing. It is almost flush with the carburetor body. Normally it is not out that far. Mine is maybe half way out. I don't if that maybe necessary for your vehicle or maybe it's causing some of your issues.
What the Idle Mixture Screw does is add more fuel to the idle fuel circuit. It increase the fuel of the air/fuel ratio at idle.
I noticed in that picture the "Idle Mixture Screw" is backed out quite a bit. It is the brass looking slotted thing to the lower left of that port in the air cleaner housing. It is almost flush with the carburetor body. Normally it is not out that far. Mine is maybe half way out. I don't if that maybe necessary for your vehicle or maybe it's causing some of your issues.
What the Idle Mixture Screw does is add more fuel to the idle fuel circuit. It increase the fuel of the air/fuel ratio at idle.
Last edited by slow-mo; 08-01-2012 at 03:11 PM.
#23
I recently adjusted the mixture per the FSM, but that was before I found these problems with my vac lines. After I get that resolved, I will definitely do a new adjustment. Thanks!
#26
AAP fixed
Found a carb rebuild kit on rockauto for $10 plus $6 shipping - replaced the AAP (which did have a hole in it). Installed the missing "jet" and now all vac lines are hooked up properly. I will do the whole carb rebuild sometime. Next to troubleshoot the EACV - I'm still getting an RPM drop at 2100 RPMs once warm.
#27
If you can find a place that has an ultrasonic cleaner, I would recomend using them to clean the parts and internals of the carburetor itself.
I went the usual route of soaking the disassembled carburetor in the gallon of carburetor cleaner. If I had know about an ultrasonic cleaner, I would have found a local shop that does it. From the research that I did, the ultrasonic action as well as the cleaning solution would have been better for cleaning an old carb.
My carburetor works fine, except for the semi-common fuel bowl draining, so maybe soaking the carb in the parts cleaner may all be that's necessary. But if I were to do it again, I'd probably buy a small ultrasonic cleaner to clean out the carb.
The following is just a general FYI for those that don't know:
The EACV (Electronic Air Control Valve) is part of the California emmisons hardware for smog control. What it does is when the oxygen sensor detects a rich mixture, it will open to allow air (from the air cleaner) into the exhaust stream to lean out the mixture downstream of the combustion chamber, i.e. the exhaust manifold.
Working in unison with the EACV at the same time is the EBCV (Electronic Bleed Control Valve). What the EBCV does is adds additional air upstream of the combustion chamber, i.e. into the carburetor. Both of these systems are ON at the same time and OFF at the same time. They work together to control the air/fuel mixture. Youll see two vacuum hoses on the passenger side of the carburetor near the very top of the carburetor, those go to the EBCV.
These two systems are part of the "feedback carburetor" the California trucks have.
I went the usual route of soaking the disassembled carburetor in the gallon of carburetor cleaner. If I had know about an ultrasonic cleaner, I would have found a local shop that does it. From the research that I did, the ultrasonic action as well as the cleaning solution would have been better for cleaning an old carb.
My carburetor works fine, except for the semi-common fuel bowl draining, so maybe soaking the carb in the parts cleaner may all be that's necessary. But if I were to do it again, I'd probably buy a small ultrasonic cleaner to clean out the carb.
The following is just a general FYI for those that don't know:
The EACV (Electronic Air Control Valve) is part of the California emmisons hardware for smog control. What it does is when the oxygen sensor detects a rich mixture, it will open to allow air (from the air cleaner) into the exhaust stream to lean out the mixture downstream of the combustion chamber, i.e. the exhaust manifold.
Working in unison with the EACV at the same time is the EBCV (Electronic Bleed Control Valve). What the EBCV does is adds additional air upstream of the combustion chamber, i.e. into the carburetor. Both of these systems are ON at the same time and OFF at the same time. They work together to control the air/fuel mixture. Youll see two vacuum hoses on the passenger side of the carburetor near the very top of the carburetor, those go to the EBCV.
These two systems are part of the "feedback carburetor" the California trucks have.
Last edited by slow-mo; 08-03-2012 at 11:28 AM.
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