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I have a 2001 Silverado with 92,910 miles on it. Recently I had a reduction of power. I had someone check the OBDII system. The code is a P0093 Large Fuel leak .... The truck is completely stock. I have owned it since it was new.
I checked the oil and it smells Ok and is not above full. I do not suspect it being injectors. Knock on wood; I have not had any problems with them yet. Can you share with me what I should try or evaluate next. I have looked and smelled for fuel leaks. Fuel filter was changed 4,200 miles ago.
Any assistance would be appreciated. Regards, Scott Via Email The Diagnostic Trouble Codes P0093 applies to the 2001 model-year Duramax. This trouble code was updated for the 2002-2004 model year engines, and received a new number - P1093. Each refers to the same problem. P0093/P1093 are defined as “Fuel System Large Leak Detected”, which could mean that one or more injectors are experiencing a high fuel-return flow rate. People usually start looking beneath the truck for signs of fuel when they read this code description, but this isn't that kind of a leak. Let's have a look at these sort of trouble codes to provide a little more insight into what they mean and how to deal with them. Most P0089, P0093 & P1093 trouble codes occur due to a problem with the fuel supply or a pressure mismatch within the high-pressure fuel rail system. A plugged fuel filter, an air leak in the related fuel lines between the engine and the fuel tank or a defective fuel filter base can all prevent the Bosch high-pressure pump from generating the desired fuel-rail pressure that is commanded by the computer. GM added a fuel supply test port to each Duramax 6600 engine – near the alternator on the front of the engine. This port is used to prime the fuel system at the DMAX factory in preparation for its initial start-up. Additionally, the test port can also be used to evaluate the fuel supply system when diagnosing an engine starting or running problem. The brass Shrader valve is covered by a black plastic cap. Pressure/vacuum gauges can provide valuable information to aid you in evaluation of your truck's fuel supply system – like that available from www.kennedydiesel.com. Under normal circumstances, the gauge should read 5” of vacuum or less with the engine idling. Replace the fuel filter if more than 5” of vacuum is present at the fuel test port. There's a specific fuel-rail pressure test that examines the fuel pressure at 2000-RPM and again at 3000-RPM. The difference between actual & desired fuel-rail pressure must not exceed 20-MPA (mega Pascals), as measured with a Tech II scan tool. If the difference between
MOST P0089, P0093 & P1093 TROUBLE CODES OCCUR DUE TO A PROBLEM WITH THE FUEL SUPPLY OR A PRESSURE MISMATCH WITHIN THE HIGHPRESSURE FUEL RAIL SYSTEM.
the actual & desired rail-pressure exceeds 20MPA, the GM service test procedure winds its way through the various possibilities for a low rail pressure, such as high fuel return rates due to faulty injectors or leaking fuel-return lines, a leaking fuel-rail pressure relief valve, and concludes with either an FRP (Fuel Rail Pressure) regulator or high-pressure injection pump replacement.
A more detailed fuel return flow test can be performed by the dealer tech where he uses a set of graduated cylinders that allow for a precise measurement of fuel return flow for each bank of injectors.
Once the cheap and easy items are eliminated (like the fuel filter or obvious fuel leaks), the most likely cause usually winds up being the injectors. Let us know what develops. Thanks for writing.