Idle won't adjust down

[SteveMc]

Idle has always seemed high in my 87 6.2 Suburban. Just installed a Tiny-Tach and sure enough, it was idleing at 700 rpm in park. I tried to get it down with the idle adjustment, but it won't go below 690. Could find no interferance from cold start solenoid or cabling. Is there another adjustment. All other swrews had the red no touch paint on them.

StevMc

[britannic]

I'm sure you've already tried these, but I'll ask anyway :D !

Did you try disconnecting the accelerator cable? What about the throttle position switch on the passenger side of the pump - is it preventing the throttle from returning? How about the throttle return spring - is it strong enough? If the IP was adjusted and the governor guide stud wasn't inserted through the metering hair pin spring (at the back of the pump), it can prevent it from returning all of the way and keep the fuel flow above.

If the IP fuel flow metering screw was turned up too much, it can cause the idle to be too high with the throttle closed.

It's only 50rpm over recommended and some even set theirs at 700rpm deliberately for a smoother idle, so if you have good power and acceleration, you may want to live with it. Otherwise to fix it might require a pump rebuild.

[Kadzban]

I ran across a 6.2 that had a high idle and it was the fast idle solenoid sticking. After unplugging it it fixed the problem.

Just a thought!

[SteveMc]

Well I decided not to touch anything on the pump untill after I had changed the injectors.. After I put in the 6.5 injectors it idles right at 650. I didn't touch a thing! It had 6.2 injectors that the pump shop man thought may have been the origional. With the Banks Turbo he suggested going to the 6.5. I havn't noticed any differance just driving it around, but will be towing 5800 lb trailer thru the southwest next month. We will see!!

Thanks for the suggestions

STeveMc 87 Suburban 6.2 w/Banks Turbo &
6.5 injectors