Threaded Mode | Linear Mode

Rawze

Is fuel spraying out at the compu-check port on the back side of the gear pump with the electric lift pump is running?... is there air in it as well?.

Are you sure no one has swapped the metering and timing solenoids?.

Has anyone pressurized the fuel tanks to 5 psi and let it sit a few hours... ensured there are no suction fuel line leaks, places the pick-up lines can suck air?.

Any red engine light in the dash?.... Also ... back up the bad delete in it,.. and then flash it with a fresh factory program that belongs to the engine (according to ser#). For all anyone knows,.. some yahoo might have blocked a fault code and hiding the engine shutdown lamp from being active.

Has anyone bothered to see if the metering and timing actuators are firing?, using a pick-up coil on an oscilliscope?.

--------------

I have seen plenty of CM871,s with no-start issues in the past. ... they are notorious for...

>> Sucking too much air after a fuel filter or davco filter changed. (pressurize fuel tanks to 5 psi, let sit for several hours).

>> Cracked pick-up tube in fuel tank. (pressurize fuel tanks to 5 psi, put hose into bucket at compucheck port,.. see if fuel is bubbly.

>> The gear pump having a snapped shaft internally, not making the fuel pressure to activate the solenoids. - Can be checked for by ensuring the fuel pressure is above 100+ psi while cranking.

>> ECM going bad.. very common if it is more than 8+ years old,. or has been purchased anywhere but a certified OEM facility. 870,871 ecm is notorious for getting flaky, especially if there is too much engine vibrations .. due to bad delete, or crank shaft damper not challenged at 500k intervals. Swapping it to another truck can fool you too... as it might start working again temporarily due to it being banged around. - Can be tested by banging ecm it while electric lift pump is running,.. see if it cuts in and out... and/or by checking if oil pressure in dash goes slightly above zero while cranking for several seconds.

>> Some idiot swapped metering and timing actuators, or some other mistake when working on the engine.

>> starts and stalls right out... won;t stay running. - turbo locked up at 100% closed, engine exhaust cannot breathe. Open up a gap between the manifold to the turbo.. see if it runs.

>> fuel shutoff solenoid has gone bad, not allowing fuel. - Removing its guts and installing the housing will bypass it.

>> can/crank position sensor one or both not reading, gone bad. - Insite shows crank/cam sensor errors.

>> A shut down is active for various reasons. Can be seen in Insite.. that is, if some idiot has not blocked the faults for it (bad deletes are notorious for blocking.hiding faults, making it very hard to troubleshoot issues).

>> engine is just a bit too sluggish to crank. Excessive carbon packed rings, alternator going bad, etc... . - Turn engine by hand w wrench and see if its harder to turn with a wrench vs. other ISX's.

>> An injector has blown out, is pushing compression backwards thru the fuel system. - Can be checked with an injector leakage tests.. ref: https://rawze.com/forums/showthread.php?...8#pid67948

>> One or more Overhead cams has slipped badly, or is not turning due to gear train issues.

>> Some complete idiot has backed off all the injector rockers, because they thought it should be adjusted like the old big-cams of yester-year. - I have seen this more than a few times over the years.

>> Someone swapping the lines off the back side of the gear pump on a common rail engine after a fuel pump replacement. Never seen this happen on a CM870/871 though.

-----------------

also note... it takes more than 2 rounds of cranking for 30 seconds each for the fuel system to bleed out and fire the engine up after a rebuild, or someone has had the fuel system apart. This after bleeding it, running lift pump several rounds.. and opening up the compucheck ports to bleed air as well.
here is a fine example of a first crank on rebuild engine after everything has been all apart ...
ref: https://rawze.com/forums/showthread.php?...1#pid27361

-=== that is what i got off the top of my head.. I might have missed something.. but take your pick.