Where is the fuel pressure relief valve on a LB7?

This valve often referred to as FPRV is located in the rear of the driver’s side fuel rail on the LLY, LBZ, and LMM, and is buried in the valley on the LB7 and functions much like the Temp and Pressure valve on your water heater.

What is the fuel pressure on a LB7 Duramax?

Note that the fuel rail pressure is at 24,053 psi. As stated previously, the fuel pressure with the Ignition relay unplugged needs to be a minimum of 2500 to 3500 psi during cranking for the return rate test results to be valid.

How much fuel pressure does LB7 have?

On a LB7 at full temp its about 4600-4800 PSI.

What should lb7 fuel rail pressure be at idle?

As it gets warmer it will drop. At 185 it should be about 4.3kpsi. It might go up or down 100 psi, that’s normal.

What causes low fuel rail pressure on a Duramax?

What is happening to cause this? The direct answer in most cases: Injectors. Simply put, the backflow or return rate is excessive so the pump does not keep up and rail pressure drops. Our testing of suspect injectors has shown backflow rates of 2x the factory spec or more.

What should lb7 injector balance rates be?

GM states that balance rates should be no more than plus or minus 4 (+4/-4) in park at operating temperature. Unfortunately balance rates do not always provide a 100% accurate diagnosis of the injector’s performance due to numerous variables present in the engine.

How long to install fuel pressure regulator in LB7 Duramax?

This guide will demonstrate the procedures to install the LBZ/LLY fuel pressure regulator in the LB7 duramax. The time taken to accomplish this was around 1.5 to 2 hours. If you don’t have all the tools listed below it may be slightly difficult to accomplish in that time frame.

Why do you need a LBZ fuel pressure regulator?

The Design of the LBZ FPR allows you to push higher fuel pressure through your truck because the LBZ FPR has more points to monitor pressure. It can provide a more accurate reading than the prior versions could. This also allows you the option to switch to the LBZ CP3 pump in the future if wanted.

How to replace the fuel pressure regulator in a Chevy?

Blaaa MAKE SURE YOU SPRAY SOME SORT OF PENETRATING OIL ON THE BOLTS BEFORE YOU TOUCH THEM. ALSO TRY TO CLEAN THE HEADS OUT SO THAT YOUR BIT WILL SEAT COMPLETLY IN IT OR YOU WILL STRIP THEM OUT. Remove the three bolts (White Circle) from the FPR/CP3. This part will not be fun.

Can a FPR be replaced on a LB7?

Just replaced the FPR on my LB7 although I went stock FPR rather than LBZ FPR. It absolutely cured the lope idle and surges and P0089 occasional codes. My truck has 236k miles. While for the most part this write up was accurate, the EGR version of the LB7 does yield some challenges although quite doable.