I just drained 3.5 gallons of fuel from the oil pan in my 03 lb7, I noticed the problem yesterday when my oil pressure dropped. All the threads I have read say injectors or lines, I replaced both side sides last summer (20,000 miles ago). How do I determine which side or injector is bad as it is a lot work to get to injectors. or if its the lines , how do I tell?truck has 240000 miles

 

check balance rates with a scan tool or have them checked. That will show you which ones are bad. You can also do an injector fuel return rate test but, its fairly involved. Id try narrowing down by bal. rate specs. Might could even do a partial tear down, remove only upper portion of valve cover and check for leaks on return rails.

 

I'd check for return leaks but it seems like there was tsb that Chevy had for the lb7 that says " if engine oil is contaminated with diesel fuel, replace all 8 injectors before continuing with diagnosis"

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