Chevrolet Repair Questions? Ask a Chevy Mechanic for Answers ASAP
Here is the procedures that need to be done to isolate the problem.
Check for restricted, kinked or damaged fuel supply lines.Check for water or contaminated fuel.Using the scan tool, check the actual fuel rail pressure and the desired fuel rail pressure. They should be within 100 PSI (690 kpa) of each other while operating the vehicle through varying loads or when commanding the pressure to increase and decrease through the scan tool.Install a vacuum/pressure gauge to the fuel system service port near the front of the engine. Prime the fuel system to 10 PSI. The fuel pressure should not drop below 2 PSI in less than 1 minute.Check the vacuum on the supply side, the vacuum should be:a. cranking - 1-6" Hgb. idle speed - 1-6" Hgc. hard accelerations - 6-10" Hgd. 3000 RPM no load - 3-7" Hge. 2750-3000 RPM full load - 10-14" HgIf the vacuum is high, check the fuel filter, fuel lines and fuel pickup for restrictions.If fuel supply test check OK, inspect the fuel pressure regulator 1 for metal debris.If there is any metal debris found on the regulator, replace the fuel injection pump, fuel rails, fuel injectors, fuel return line assembly, all high pressure fuel pipes, indirect fuel injector, and fuel feed pipes (pump to indirect fuel injector). Clean and flush all fuel chassis lines, fuel filter housing, filter pipes, and other engine mounted fuel system pipes not replaced. The filter housing should be inspected and cleaned with a new fuel filter installed.
If the test procedures were followed, they should have been able to isolate the problem down, I will reopen your question and allow some of the other techs to give there input, maybe they can add something else to solving your problem. Do not respond to this post or it will lock me back into
your question. Thank You for using just answers.