My 1989 dually has a high idle problem. I took apart the TBI unit along with the poweraid block. Clean them both with fuel injector cleaner and put back together. If I tap the accelerator it idles high until I "tap" The spring lever on the TBI unit itself and then the idle goes down to normal. I have tried using wd40 but it seems that the butterflies are not seating properly. I thought butterflies just open and close and thats it?

Could these things be wore-out? Has anybody have this problem before? What it the solution?

Thank you for your help!!!

 

You should probably ask this in the 351 engine forum.