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 Post subject: Crank no Start - Strange Fuel Pressure Readings
PostPosted: Sun Jun 29, 2025 5:43 am 
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Joined: Wed Jun 25, 2025 7:00 pm
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Hoi guys, my name is Juan and I'm contacting you from South Africa. I have a situation with a 2007 model Jeep Liberty KJ 2.8 CRD.

The situation that I have is that the car came to me as a crank no start. I've done all the things, replaced the camshaft sensor, I've replaced the crankshaft sensor, I've replaced the fuel pressure regulator, I've replaced the fuel pressure sensor, the CP3 pump is still good, the ASD circuit has been checked, basically everything.

It has no codes, but the strange thing that I've noticed is that while I crank the vehicle, it doesn't show me fuel pressure, but the fuel pressure voltage is there, the sensor voltage, when I view the live data, the voltage actually goes up to almost 2 volts, which tells me that the system is generating enough pressure, but it's not displaying any pressure.

It's as if the computer is not translating the voltage over to pressure. So normally on all your sensors you would get voltages and then the computer will change it over to bar or to Celsius or to RPM or whatever, and it doesn't want to start.

If I put quick start, it fires up and then it dies again. It doesn't actually inject fuel, the injectors aren't triggering. So, but the main thing is the fact that there is fuel pressure voltage, but it shows on the live data, it shows that there is zero PSI or MPA pressure. I'm using an Autel tool, and yeah, if you guys can be of any help, I've actually got another lock set which I've installed as well. The vehicle responds exactly the same.

On all the main sensors, the fuel pressure sensor, the crankshaft and the camshaft sensors, I've wired in a new circuit up to the ECU, between the ECU and the sensor, and it doesn't seem to make any difference.

The timing belt seems to be a bit worn. I have installed the timing tools. The timing doesn't seem out, but the belt seems a bit worn. Maybe can the belt be causing this..?


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 Post subject: Re: Crank no Start - Strange Fuel Pressure Readings
PostPosted: Sun Jun 29, 2025 7:38 pm 
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Joined: Thu Dec 13, 2018 10:05 pm
Posts: 184
Location: SoCal
Only thing i can suggest is have you bleed all the air out of the lines? There is a manual plunger on the fuel filter assembly and if you push it enough times it should get really hard to push in. Then with the bleeder screw, loosen it up to let the fuel and air out. Keep doing this till all the air is out and nothing but fuel comes out in a steady stream.

These jeeps did not come from the factory with a lift pump in the tank. The CP3 draws fuel from the tank and the fuel lines have been known to let air in at the fittings. You can easily add one, just do a search on here on how to do it. Been documented plenty of times.

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05 CRD; Rebuilt top end w/ARP studs, EGR delete, SEGR, 3.7L HD cooling fan, Samco hoses, in tank pump, JBA coil overs & control arms, KK clevis fork, 1/2" cradle drop, 1/4" motor mount lift, WJ rear upper trilink w/WW mount, WJ lower control arms, 4:10 gear, front/rear air lockers, ARB bumper, Rock Lizard sliders/roof rack, Mod T-stat


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 Post subject: Re: Crank no Start - Strange Fuel Pressure Readings
PostPosted: Mon Jun 30, 2025 6:20 am 
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Joined: Wed Jun 25, 2025 7:00 pm
Posts: 2
Hi 03black!

Thank you so much for your replay!

All the air has been bled out of the system and a lift pump has been installed.

Maybe this screen shot from my Autel AP200 will shed some light on my issue….
Notice while cranking, both crank and cam signals are present, fuel pressure set point and fuel pressure voltage, but rail pressure seems to be absent….

Image

This does not make any sense….? :dizzy:


Can’t get the image uploaded, here is the text form of whats happening in the picture..

FUEL PRESS VOLTS
1.68 V

FUEL PRESS SETPOINT
52766 kPa

FUEL PRESSURE
0 kPa

CAM POSITION SENSOR
107 rpm

ENGINE RPM
214 rm


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 Post subject: Re: Crank no Start - Strange Fuel Pressure Readings
PostPosted: Mon Jun 30, 2025 9:59 am 
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Joined: Thu Dec 13, 2018 10:05 pm
Posts: 184
Location: SoCal
You wouldn't happen to by chance mixed the fuel pressure senor plug and the #4 injector plug by mistake? It is very common to mixed the 2 plugs up when reassembling or troubleshooting as the 4 wire plugs can easily be plugged into the wrong spot. They are not "keyed" and many people have mixed them up by mistake. They are at the back of the engine near the #4 injector and the wires are long enough to reach each other. This will also cause a no start condition.

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05 CRD; Rebuilt top end w/ARP studs, EGR delete, SEGR, 3.7L HD cooling fan, Samco hoses, in tank pump, JBA coil overs & control arms, KK clevis fork, 1/2" cradle drop, 1/4" motor mount lift, WJ rear upper trilink w/WW mount, WJ lower control arms, 4:10 gear, front/rear air lockers, ARB bumper, Rock Lizard sliders/roof rack, Mod T-stat


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