Bosch High Pressure Fuel Function Block (includes PRV and RPS) 01-04 GM 6.6L Duramax LB7

Bosch High Pressure Fuel Function Block (includes PRV and RPS) 01-04 GM 6.6L Duramax LB7The LB7 Duramax as being the first of the light duty, common rail diesels to hit the market, sometimes did some things a bit different than those released later. One of these instances is the high pressure fuel function block as opposed to a traditional fuel rail. That said, the idea is still the same in that it houses the pressure relief valve (PRV) and rail pressure sensor (RPS) and is responsible for the distribution of highly pressurized fuel.

The LB7 Duramax as being the first of the light duty, common rail diesels to hit the market, sometimes did some things a bit different than those released later. One of these instances is the high pressure fuel function block as opposed to a traditional fuel rail. That said, the idea is still the same in that it houses the pressure relief valve (PRV) and rail pressure sensor (RPS) and is responsible for the distribution of highly pressurized fuel. Now, why would you need to replace this function block? As with any diesel, if you can't maintain adequate fuel pressure, the truck will run poorly, and if low enough, not at all. This function block houses two very important parts of ensuring adequate fuel rail pressure, being the PRV and RPS. The relief valve is responsible for controlling rail pressure and bleeding off anytime there is excessive pressure. However, over time, this valve can, and will, wear out causing rail pressure to bleed off before the set pressure has been reached. Secondly, the rail pressure sensor, as with all things, can fail, as well. When this happens, its unable to send an accurate signal of rail pressure to the ECM, so its unable to match desired versus actual rail pressure. If the ECM is unable to determine what the rail pressure actually is, it can over or underpressurize the system. If you're dealing with symptoms such as these, sometimes its easier to merely replace the entire block.