I have a 2009 D6K 3450 hr on C6.6 engine. The engine will not start without a shot of either. Once started it tends to lose power while under load at wide open throttle. Had cat mechanic scan with cat computer and only codes were same as on display. Low fuel rail pressure. I have replaced all three fuel filters, checked supply and return lines and even replaced the fuel regulator and fuel pressure sensor on the common rail. Still will not start without either. I know either is bad but it’s the only way to get it cranked. Cat diagnosed fuel pressure is good while running at 5,000 psi. You can shut of engine and immediately try to crank and it will not start. No smoke out the exhaust or anything while cranking to show evidence of fuel under compression. What could be the problem? Fuel injectors, injection pump or transfer pump? Engine just isn’t getting enough fuel pressure to fire injectors.
No smoke out of the chimney when cranking with a warm engine is an indication that the pressure in the injection system is not reaching the minimum value required to fire up the electronics that control the injectors. If Cat were on the machine with ET what fuel pressure did it show while cranking and what RPM was it cranking at..? Too many D6K models to speculate which one you have. Need a Serial Number.
I don’t recall the mechanic saying what the pressure was at crank or what the rpm was. New batteries on machine and it sounds like it always has even though I know that’s something to consider. Serial #FBH1325
How’s compression?
I find that somewhat strange. If the engine was reluctant to fire up then you'd have thought he would have been watching the fuel pressure and RPM like a hawk while it was cranking. Question: Did this issue first develop in that the engine would start OK when it was cold but was difficult to restart when it was hot.?
The last few times it was cranked it just took longer and longer to fire off. I took machine on into a Cat shop today. Turned out the injectors are bleeding off causing it not to fire. Normal output is 30 ml or less in a 30 second crank test. This engine is putting out 90 ml in 30 seconds. Going to replace the injectors now.
Have them put a guage on the fuel rail and see if it matches what the computer tells them. My first check would be the fuel transfer pump and the inlet screen of that pump. Something is causing the pressure to be too low and I don't think clogged injectors would be the cause. A fuel system flush wouldn't hurt anything either. It would eliminate the possibility of contaminated fuel.
How many hours on it? C4.4, C6.6 usually needs a new set of injectors when they reach 5-6000 hours to maintain full engine power so I'm sure that will fix it.
5000psi is good enough to get it to start. If your engine is running and you are only making 5000psi. Then that is too low. Your dealer needs to quit screwing around and perform a fuel return flow test. At those hours you likely have a bad injector and returning to much fuel. That will cause the rail pressure to drop. Did the "tech" check and see how many times the pressure relief valve has opened and for how long? If it has opened too many times and for too long. Then the rail pressure can cut a groove into the rail. All of this should have been tested and checked that day. Either the "tech" is lazy or doesn't understand hpcr fuel systems.
Holt,Mustang, or Warren?
Based on what was replaced prior to that, injectors are probably the next step. And if that doesn't fix it you will be in for a new HP fuel pump as well.
Update. Cat did a flow back check and injectors need replacing. Replaced all 6 as well as injector lines. Fixed the problem
Warren