CRANK-NO START ‘00 M1079a1

[expeditionnw]

Working on a model year 2000 A1.

this is the pre-battery disconnect era.

The army threw a bunch of parts at it, including a new ECM, new circuit board, new TCM, new oilpressure sensor.

Truck cranks with button, trans controller illuminates as normal.

I converted to two batteries.

changed fuel filters.

Tested the crank pressure sensor by unplugging. Still no start.

tested P2 connector at ECM. Pin 52/53 have constant 24v. Pin 70 24 when ign on and cranking. Seems to communicate with my scanner fine.

tested IAPCV. 10.2ohms which is in spec.

My snapon scanner shows 0.00 injection control pressure.

truck fires on happy gas, so I know the internals are working.

I swapped the ecm with an identically mapped unit from a working truck. No start on new ecm.

I’m beginning to suspect a bad HEUI pump, or a spun drive gear.

before I pull this apart, is there anything else I am overlooking?

 

[Ronmar]

Well no ICP, no squirt… does the engine have engine oil pressure when cranked? Is the oil feed to the HEUI pump clear and feeding oil when the engine is cranked? The PCV coil may ohm Ok, but is it actually sealing to allow pressure to build? have you removed that and inspected its operation? If I recall there is also a mechanical pressure relief valve, is it sealing?

I guess you could remove the PCV and fit a line in its port and see if the HEUI pump feeds any oil when cranked.

is all the downstream high pressure plumbing from HEUI pump to injectors intact. If you can access and watch them while cranking, a broken HP line should stick out like a sore thumb, and could dump all your oil and pressure back into the crankcase keeping you from building ICP…

Yes it could be a HEUI pump, but garbage in = garbage out…

 

[GeneralDisorder]

Must hit 870 psi injection actuation pressure or the injectors won't be fired. If you aren't getting that then you have a fuel supply or HEUI problem.