2003 Jeep 2.8 CRD wont start

[Abrie]

Hi All

Thanks for accepting me. I recently bought myself a 2003 Jeep Cherokee 2.8 CRD for a great bargain. It had one problem, it doesn't start. Initially i thought how difficult can it be to diagnose the problem. Well the last two weeks since I've bought it I've been losing my hair, doing research till the sun comes up. I've tried everything. On of our local 4x4 communities here in South Africa recommended you guys, i really hope you can help me, so here it goes.

The Jeep is turning over but will not start. I've bought a elm327 obdii reader and found no errors on the ecu. I've measure for voltage on the injectors and found that they are not firing. Tested the asd relay and tested that there is power when switched on. When switched the fuel quantity valve actuates. I've read that if the rev counter lifts while cranking the camshaft sensor is working. I've replaced the crankshaft sensor with an OEM one. Before i plugged in the new crankshaft sensor I've measure the connector coming from the ecu and found on the 3 pins while switched on 0v, 2.5v, 2.5v. The injector pump was replaced by the previous owners by n refurbished one. I've bleaded the system till there is no more air in the system and measured the fuel pressure sensor on the rail it goes up to about 3.7v while cranking. Is there any other sensor or condition that can cause the injectors not to get power. Temp sensor, oil pressure sensor, battery temp sensor, sensors on gearbox?

Thanks in advance

 

[turblediesel]

Maybe a safety interlock? Foot brake, neutral/park, ignition switch interlocks?

Glow plugs working? Glow plug relay/fuse?

Obviously I don't know... Just asking.

 

[Abrie]

That is what I'm looking for. What signals and conditions will initiate the engine to start, more specifically supply power to injectors.

 

[JeepinJarhead03]

1. if you dont get over 1000psi fuel pressure the ECU will not pulse the injectors
2. ECU looks for signals from crank position and cam position before pulsing, no signal , no pulse

have you tested cam position sensor/plug?

 

[Abrie]

I'm busy testing the signals with a scope as close as possible to te PCM. Something interesting i've read is that in the diesels the is that the crank sensor does net get 5v from the pcm but rather poroduce a ac signal. An other thing is that one of my friend pointed out the 2003 did not came out in the 2.8 but 2.5 diesel, but from the vin it is indicated as an 2.8. Is there any way of telling from looking at the engine?

 

[Abrie]

I've tested the cam sensor, gives a nice block wave while crancking. Tested the crank sensor gives a nice sine wave. Tested the fuel pressure sensor goes up to about 3.7v that is 180kPa if I'm not mistaken, but still no pulse on any injector. Maybe the ecu?