how do you adjust the jrsc fmu? what does it do when you tighten it and what does it do when you loosen it?

 

You can't adjust the JR FMU. The screw on top only controls ramp up rate. In other words... how quickly the fuel pressure goes up as you get closer to the vacume to boost crossover point. Basically it's a fixed rate RRR. Also, if you do mess with the screw on top of it you'll never get it back to the way it was. Jackson sets these properly for the 6psi kit inhouse and doesn't recommend changing the setting. This is why you'll find the screw is glued in place so you can't turn it w/o some force.

 

raises and lowers static fuel pressure under boost

 

Probably best to $hit can the JR, and pick-up a CarTech FMU (RRR) or something like that. That way you can adjust it to where you want it. Also, there is a possiabilty that the JR tends to trash out the injectors over time, due the high fp pressure. Some peeps have seen as much as 100 psi in their systems...

 

Clockwise on the allen bost increases, counter- decreases