Engine Turns Over, Won't Start, P0563 System Voltage High

WWDiesel · **Posted:** Fri Jun 03, 2022 12:46 am

This is what the Ambient Air Sensor looks like:

Location:

Billybob · **Posted:** Fri Jun 03, 2022 2:32 am

Yeah I do not have that on my 2002 2.5 Export CRD!

It is shown in the logic diagram but when I look in the Parts Manual....it shows the pictures for all the sensors but that particular sensor is stated to be "Not Fitted on this Model". :shock:

Not a major problem....I have survived for the last 20 years without that sensor!

This is only the second time I have been wrong in my long life........I once thought I had made a "mistake" but I had not! :wink:

Hope the OP can find the problem on his Jeep!

Thanks for your patience and your help WWDiesel :wink:

quietas · **Joined:** Tue Nov 14, 2017 5:02 pm **Posts:** 18

Nope, no luck so far. It's time to sell it, burn it, live in it down by the river, or take it to a mechanic.

quietas · **Joined:** Tue Nov 14, 2017 5:02 pm **Posts:** 18

It's been a bit but I went out and fiddled with the CRD for a bit. A friend who is a big diesel mechanic (Fords, Chevy, Cat) and has a couple of his own came over to help. I pulled out his Snapon oscilloscope and hooked it up tp the fuel rail pressure sensor. No reading on the tool. I had already unplugged power from all the injectors, then I pulled the feed line to the fuel one of the injectors. Turning the engine over worked this time and it could crank continuously instead just 3 times. No fuel spraying out when the engine cranks.

His guess is the high pressure fuel pump but it seems everyone here says is is highly unlikely as they are indestructible.

I plugged everything back in and secured the fuel line. Now the engine is back to 3 cranks and it stops turning over until I turn the key to off and try again for 3 more cranks.

Fuel rail sensor? Fuel solenoid? Something else?

quietas · **Joined:** Tue Nov 14, 2017 5:02 pm **Posts:** 18

Another update. I unscrewed the fuel line feeding the fuel rail and I get fuel coming out when I crank the engine over. It also will crank continuously, but when I screwed it back tight I only get the 3 cranks before it stops. Disconnecting the Fuel Rail Pressure Sensor gets a single crank out of the engine, plug it back in and I get 3.

At the fuel rail feed line is it supposed to be high pressure gushing fuel out or a steady flow? If it's a steady flow I think the pump is fine.

I'm wondering about the symptoms for the Fuel Rail Pressure Solenoid and the Fuel Rail Pressure Sensor.

dimedriver · **Posted:** Wed Jul 27, 2022 3:10 pm

Leading up to you replacing the alternator, I'm assuming you jump started the jeep a few times. When jump starting did a jumper lead ever touch the ECM?

Try putting a volt meter on the 5volt power and ground leads of the map sensor. Should be 5voltish with key on and while cranking. I suspect a bad sensor or a shorted wire is pulling this voltage down. This would make all sensors fed by this 5volt source have issues.

If you are not getting 5volts start unplugging sensors with the key on. If you unplug one and the voltage jumps to 5volt that is the sensor I would investigate 1st.

Engine Turns Over, Won't Start, P0563 System Voltage High

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