Originally Posted by
dougmac
Hello! I am new to this form. I found this a very interesting thread. I am a diesel mechanic and have my own perspective on this problem..
The first thing I check when I have a rail pressure fault on a common rail fuel system is the injector spill-back. Excessive spill back appears to be the problem most of you are facing. I see it mentioned but not being addressed. I imagine that is due to the cost of the injector replacement.
Common rail systems return very little fuel back to the tank under normal conditions. On a Duramax, if every injector was at the the maximum allowable spill-back, at an idle you would only be returning 100ml per minute to the tank.
Excessive spill back causes the fuel demand to exceed the high pressure pump's capacity. As the fuel temp increases and the fuel viscosity decreases the spill-back will increase.
I also theorize, as the spill-back increases the excessive returning hot fuel introduces more heat into the fuel tank further exasperating the problem by elevating the temperature of the fuel in the tank.
From my perspective, you may be able to mask the problem with program tweaks and beefed up coolers but in the end to really solve the issue, you probably need to address the injector problem.
Doug