Somebody already messed with the main pump screw dont know where im at, can i turn it the whole way in, or the whole way out to find where im at, where should i be for the most fuel, thank you<br> <br>

 

First off...I wouldnt turn it in anymore without at least a pyrometer. Turning the screw in or clockwise will give you more fuel. However, turning the screw all the way in has caused a few runaways on some trucks. The best advice I can tell you is to play with the settings a little and find the sweet spot. Go in small increments. When you get to the point where it takes a while for the RPMS to come down when revving it up. You are right at the brink of a runaway. I have my screw turned in about a 1/4 turn from where the collar was welded on and the screw is hard to turn. Seemed if I went any further, the RPMS were SLOOOOW to come down in between shifts.

 

truck has a pyrometer and the screw was turned 2 times, it go above 1100