2005 gmc c5500 6.6 lly 1093

[Justin1972]

I have a 2005 GMC C5500 with LLY and keep getting P1093! Have change the fuel rail relief on the drivers side rail and same thing. Have done a return test on the injectors left bank less than 10cc and the right bank the same reading. Change the high pressure pump and drove it ten miles and the code came back. Not sure what to do next. Have installed an Air Dog 150 hoping this would help but the same thing. I do know that since changing the high pressure pump i can power brake it and get the code to set. At first it only did it when pulling the goose neck trailer loaded. Need help!!!

 

[Brent@LDS]

What kind of miles are on the truck and does it have original injectors?

 

[Justin1972]

116,000 miles has had some injectors replaced before i got the truck. the balance rates are with in specs. I bypassed the fuel filter today and got the same thing. I have a small code reader and can see some data the fuel pressure when the code sets varies from 6500 to 7900 psi. the longer it runs the less the fuel pressure is at idle. the problem has gotten worse since replacing the high pressure pump.

 

[Mike]

Have you checked the CP3 pump return rate?

 

[Justin1972]

No i havent! Just replaced the CP3. Got it from GM. I guess it could be bad! Being that it was a reman pump from GM. I do the problem has gotten worse since replacing the CP3 pump.