How easy is it to tune with the Adj. FPR?
Where is it on the Jeep?
if you use a hesco it goes in where the stock one is installed. if you have a generic one (the route i took) then you need to somehow replace the stock one - what i did was to use a stock FPR and plug the return port (threaded and put a screw in with teflon tape on it) and then use the schraeder valve to connect to the new FPR - hesco makes a plug disc as well, i had a spare stock FPR so that didn't cost anything. I'll post some pics of these 2 when i have some time to take them - it's pretty straight forward and would work with any generic adjustable FPR that has a high pressure port, a return port and a vac port (you want that as that's the way the stock one is).
On my Mallory as well as most of the generic ones on ebay there's a gauge port on which you can have a gauge to see the pressure - easiest way to tune it is to start the engine, let it idle, unplug the vac port and adjust the pressure and monitor the gauge - stock pressure uncorrected by vacuum is 39 psi. Sometimes the gauge is off so first thing i would do is to verify what the stock pressure shows at on the gauge - for that you can connect the new FPR to the schraeder valve and have the adjusting screw in quite a bit to prevent the fuel come out on the return port of the new FPR - you still have your stock one installed - let the engine idle and take note of the pressure that is displayed - can be 38psi for example which means that is your starting point. From there remove the stock FPR, install the blocking one or the blocking disk and put the contact a few times to build pressure in the rail - adjust the screw until you are close to what the stock pressure was. Start the engine and let it idle (you can also jump the Fuel Pump relay) and with the vac port unplugged set your target pressure - let's say you are targeting your injector static flow to 18.5lb/hr, that is an increase of 1.1lb/hr compared to the stock flow - you need 5psi more final pressure so your gauge should show 44psi (or in case it's off like in the example above 43 psi). Put the vac port back and take it for a test drive (try to hit wot and get a feel for it, best if you do a run with the stock pressure before the change so you can compare) - you can go lower or higher and compare the runs, i was up in the 49s or 50s at some point when in boost but that was corrected by the boost pressure thru the vac and i think that would be too much. For 18lb/hr static flow compared to 17.4lb/hr stock you need an increase of 3psi in the fuel rail and i would say that's the best place to start and then go up or down from there.
Best case scenario is to have some logging capabilites to monitor your AFR via a wideband o2 but if your Jeep is not smoking black and your spark plugs keep their nice color you're good. Of course there's a downside with the mpg, but if you drive it normally in closed loop (you don't hit wot too often and accelerate mildly) there shouldn't be any penalty on that once the PCM relearns the trims. I'll try and post some pics of the adjustable FPR and modified stock one with the plug when i get a chance.
