Just bought this truck in july. I had read up on these trucks well before the purchase, so fuel pressure gauge was in on day 2. Mechanical gauge on top of fuel filter housing. When i put this in the pressure pegged the 15 psi gauge. My cummins mechanic said that i just had a strong pump. Over time the pressure came down to 10-12 psi. Then I checked and its down to 2-4 psi running at idle. I bumped the starter and check the gauge was up holding 9-10 psi, but running again it is back down low. I feel like air leak because the pressure relief at shut down is faster. Havent found time for in cab gauges yet. Any suggestions on electronic gauges.