need help why the mikuni carb. won't idle

My 88 d-50 has idling issues. The story goes the truck was running fine but would not start after setting over winter because of broken brake lines. After I repaired the lines and the truck would not start. Fuel pump seems to check out ok but no fuel was getting through the carb. Bought a carb kit and replaced pump diaphragm and float valve and some other items . Got the engine running and appears to take gas good, the problem is, it won't idle and quits running below about 800 rpm. Checked vac. hoses and idle adjustment screw. Does anyone have any info. on the idle circuit or what could cause this issue on the mikuni-solex stock carb. model 30-32 didtf? Just took off top of carb. to replace the items. Would the feedback solenoid have anything to do with it? I would like to convert to weber or holley but can't afford to at this time. Thanks

Check the fuel cut-off solenoid. If it fails electrically or its jet is clogged, the engine won’t idle.

I used a hand vacuum test pump to check the needle seat for leaking ~ try that plus remove the float and give it a shake IF it has fluid inside replace it ~ the 1987 Mikuni OEM float should be an exact replacement ~ your engine might be flooding ~ a vacuum pump test is valuable for checking all the diaphragms on your truck including the vacuum advance on the distributor & the 2nd dary butterfly actuator on the carb & vacuum lines too ~ wishing you a quick fix George

Thanks, I'll give it a try. Do you know what parts make up the idle circuit? Is the feedback solenoid the same as shut off solenoid located in center inside of carb.?

The feedback and shut-off solenoids are not the same and have different functions. The shut-off solenoid cuts fuel to the idle circuit at engine shut-off to prevent dieseling and during extended deceleration periods to save fuel. Under other conditions, it stays open allowing fuel flow.
The internal feedback solenoid operates at rpms greater than idle speeds. The computer drives its on/off duty cycle based on inputs from the oxygen, TPS and vehicle speed sensors, to name a few. Its purpose is to maximize fuel economy under steady, low to medium demand driving conditions.
For more info about the solenoids and the idle and primary circuits, look at the guide included in post #8 of this thread:

http://www.mightyram50.net/vbulletin...3354#post73354