D 350 Pickup L6-359 5.9L DSL (1989)
Idle Speed: Adjustments
Low Idle Speed Adjustment Screw
1.
Attach an optical tachometer such as Cummins No. 3377462, or Snap-On No. MT139, to read the engine rpm.
2.
If idle speed is not within specifications, loosen the low idle speed screw lock-nut and rotate the low idle speed screw until the specified rpm is
reached. Loosen the low idle speed lock-nut with Cummins tool No. 3823750 or equivalent.
3.
Adjust the low idle speed screw to 700 rpm if the vehicle is equipped with an automatic transmission, or to 750 rpm if the vehicle is equipped with
a manual transmission. If the vehicle is equipped with air conditioning, set the low idle speed with the air conditioning ON.
4.
Tighten the idle speed lock-nut.
