Engine/Transmission (1994 - 1998) High Idle Screw

[nfox]

Where is the high idle screw, and do i need to fool with it?What tools do i need to adjust it?

 

[bmoeller]

I don't know if the pumps on the 12v are similar to the pumps used on some of John Deere engines. The Deere pumps, on the lower rear of the governor housing there is a small square cover. Behind are two screws. I don't remember which is which but, one is for the high idle adjustment and the other is for setting fuel delivery to turn up the HP. Depending what your goal is, changing gov. springs might be the best/only way to change it on your pump.

 

[Missouri Mule]

nfox,

High idle screw is on side of injector pump govenor. It is about 3 to 4 inches in front of low idle screw, it is one of these no tamper srews ( plugged with gunk). It is used to set max fuel flow to injector pump ( basically it changes the spring settings).



bmoeller is right there are two screw on backside of govenor. They usually have a wire threaded thru them so you can not adjust. They change fueling and by changing spring settings and/or angle of plate as I recall, some what risky to play with them.



If you want more fuel flow, a fuel plate would be more pratical this way you can always put back to stock performance by dropping the oem plate in.

Govenor spring kit will allow you to increase rpm above 3000 to 4000 rpm depending on which kit you get. ( which is increasing the rate of max fuel flow for a specific top rpm) I don't think of the govenor as defueling but rather staying at steady rate of fueling(maintains fuel flow) when it reaches the max, my truck doesn't slow down it maintains the same speed at my top rpm( little over 2600 in 5th and 2750 in 4rth).

 

[shendren]

i didn't know there was a "high" idle screw on my 12v pump. i thought there was just the screw on the bottom rear that i adjust my idle with???????

 

[Missouri Mule]

That is your low idle screw Shreden it works like a low idle screw on a gas job(sets rpm while engine is at idle). You know that though.

The high idle screw is a misnomer as it has nothing to do with setting the idle at start up (especially during cold weather) like it does on the gas engines (when the choke is activated).

The high idle screw is for setting max fueling/rpm, when the govenor spring reaches that setting fueling levels off.

The idle screw I believe will only let you adjust to about 3000 rpm before fueling levels off ( but you can stretch the spring to much which causes loss of fueling/power).

If you want more than 3000 or more than 4000 rpm you need to replace springs in govenor.

As I recall when replacing springs one can adjust springs (high idle) from inside of govenor.

 

[Stixx]

I know a guy with a 97 that turned his high idle all the way in and he would start defueling at 3500.

I turned mine in some and it hits 3000 and about 2800 in 5th.