Project 7.3

[Bduck]

Next Task, there is a fuel pressure regulator spring located in the top of the engine mounted in fuel/water separator housing, very easy access with 2 screws in its own external cover attached. This stock spring is a noted culprit for engine to quit running which weakens under heat cycles of the engine not supplying adequate fuel press to fuel injectors. So, prior to replacing spring I installed a fuel press gauge in the cab. Fuel press at idle was 62psi, when accelerating to 75mph on interstate fuel press as it should drops off between 50-55psi and once speed is stabilized press recovers to 62psi. Truck runs really well which I would think its ok. Now, I replaced the spring and surprisingly fuel press at idle came up to 92psi which is 30psi more than old spring. I then drove truck on a lessor speed trip at 55mph, acceleration press dropped off to 76psi and recovers to stabilized 92psi. I don't know if the limits of the fuel press has changed but previous limit was 75-85psi. Research indicated the original stock spring was not heat treated and was the issue of weakening. The new spring is treated. New spring is $25.


      
Original spring            Comparison with
                                   ink pen spring