1985 Chevy S10 pick up 1.9L engine 4cyl . carb model DCH340 - - Engine runs well but will not idle . It has two solenoids on the carb , vent switching and slow cut . Both operate when battery power is applied directly to them off the carb .

unless you know someone that can rebuild the carb i would buy a rebuilt carb - easiest way and chepest in the long run.

check for vacuum leaks frist. then you may have to adjust the idle mixture. if the screw plugs are out it's easy, if not they will have to be removed, here's the info on how to do it. let me know what you think. mws919 i'll send the pic if you post email

IDLE MIXTURE ADJUSTMENT

- Set parking brake and block drive wheels.
- Place transmission in neutral.
- Remove carburetor assembly.
- Drill a hole in seal plug and remove plug with proper tool. After drilling, be sure to remove shavings with compressed air.
- Reinstall carburetor assembly.
- Make idle speed and mixture adjustment with the following conditions:

Engine at normal operating temperature.
Choke open.
A/C off.
Vacuum lines for distributor, idle compensator and EGR valve disconnected and plugged.
Idle compensator hose closed by bending hose.
- Turn the idle mixture adjust screw all the way in and back out 1 1/2 turns.
- Adjust throttle adjust screw to 850 rpm (M/T) or 950 rpm (A/T).
- Adjust settion of idle mixture adjust screw to achieve the maximum speed.
- Reset throttle adjust screw to above rpm.
- Turn idle mixture adjust screw clockwise (lean) until engine speed is down to 800 rpm (M/T) or 900 rpm (A/T).
- If A/C is installed:

Turn A/C on "Max COLD" and set blower to high.
Open the throttle to approximately 1/3 and allow the throttle to close. This allows the speed up solenoid to reach full travel.
Adjust the speed up controller adjusting screw to set idle at 900 rpm.

I have tried all this but the engine will not run unless the the throttle screw is adjusted far in and the engine is running very fast . Any reduction of speed stalls the engine .
Thanks for trying to help .I can not help but think the problem is electrical and the control of the slow cut solenoid .

so you need to give it more air across throttle plate to make it run? sounds like you have a idle air control valve promlem. let us know.

if I have an idle air control valve problem ,how do I correct it ?

at this point you'll need a scan tool to read pos of valve and to command it closed and open. it can be done using the batt and a few wires but, it's very trickey. if not done correctly it will hurt valve. other than checking the wiring going to it, you may have to bring it to a repair shop. let us know.

I think with the limited equipment I have , this problem is beyond my ability to repair . Hate to take it to a shop because it says I've failed . Thanks for your input . You have been helpful .

good luck with it, any thing eles, we'er here.