Hey guys, as it's been getting colder (colorado) the last month or so, I have noticed my truck slowly taking longer to start. I figured the injectors were shot since I have 138k on the truck, so I had a cummins mechanic put in a 6 pack of stock remans for me. It ran ok for a few days, and back to the hard starting. Recently (this has been going on for about a month now) if I let the truck sit for 24 hours and try to start it, it needs a shot of ether. (I unplug the grid heater when I ether it)

I left town for 4 days and left the truck at home plugged in, came back and it took a few cranks but started up. So now if I plug it in it starts. I'm guessing because it's keeping the oil warm and less viscous so it cranks faster. Yesterday I took it to the grocery store and listened to it idle.. It went from kinda loppy low RPM's (800) to loppy high RPMs (1000) and then would smooth out for a bit.

We (my cummins guy) have flow tested the lift pump (stock mounted on back of filter housing) and it had greater flow than spec (we have not tested fuel line pressure yet). Tested the injector return-nothing leaking by. Low pressure side of the CP3 as well as the high, everything was to spec. Tested the pressure relief valve, nothing leaking while cranking or running. I have tightened the brass injector lines and he is sure he torqued the tubes and injectors to the correct inch/lb settings. We have load tested the batteries after they sat all night and they were both in the green. We replaced the FCA hoping it would cure it since it's a cheap fix, it started like a champ for 3 days and back to the same thing. I've also checked the wiring harness(es) that run under the oil filter. Unless I was looking at the wrong one, they all seem to be fine.

He ordered a check valve for a line on the back side of the block somewhere ($10) thinking it may be leaking fuel off while it sits. We haven't put that part on yet as it snowed 10 inches here yesterday. He also said there is a check valve under the fuel filter housing somewhere that might be our next option.

I've got a neighbor that's going to let me borrow his scan tool soon so I can read the rail pressures while I'm messing with it. Does anyone have any suggestions? It seems like it's getting air in the fuel system from somewhere. I think I have read nearly every forum on these symptoms and they either never say what the fix was or it's something I've already tried. IDEAS PLEASE!!

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Just edited my sig..

 

i would check the rail pressure at cranking speed, going to take somewhere around 1400 to start it, if its not making that i would consider the cp3

 

check your fuel lines for a pin hole behind ever clamp that holds the lines to the frame.dont laugh i worked for two days to find this was the problem the whole time.this may not be your problem but you might want to check.