Hello, everyone, I am new to Yotatech. I recently purchased an 89 22RE 4x4 pickup single cab. I love it and have had a lot of fun driving. I am in the military and just returned from a month-long training rotation. After I started my pickup for the first time since returning I noticed idle surging whenever I pressed the brake pedal. Being stationed in Alaska, I do most of my winter driving in 4H anyway since there is always snow on the road. When I engaged 4H I noticed there is no idle surging when I pressed the brake. I switched back to 2WD and pressed the brake again and the idle surging returned. I am new to these older pickups, so I am curious if anyone with more experience could help me diagnose this. Any help is appreciated.

 

Hey man, it sounds like a vacuum leak! Check all vacuum connections to the brake booster and intake manifold, if you are unable to find any bad vacuum lines or connections, it sounds like your brake booster diaphragm seal has went kaput. Hope this helps. Also just to be sure you should probably bleed your whole brake system before changing booster!

 

There's a fuel cut feature- it kicks in if the revs are high with the throttle is closed (like coasting in gear) and also can be affected if there is a leak as stated above or something is out of adjustment. I believe pressing the brake lowers the cut-in rpm.. so it sounds like you're idling too high for whatever reason- vac leak, throttle slightly stuck open, idle air set too high, etc.
Im in Juneau, how about you?