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How to check fuel pressure

21K views 8 replies 3 participants last post by  Siner)8 
#1 ·
Hi does anyone know how to check fuel pressure on an 05 grand Cherokee 5.7 Hemi. Trying to check if my fuel pump is still good. Truck is having issues starting.
 
#2 ·
Hard starting can be a starter, battery, etc. Not necessarily a fuel pump. As for testing the pressure, I can't recall at the moment. I forget if you need to disconnect and injector or if the 5.7 has a test port.
I have an autoenginuity scanner and in Chicago, if you want to meet up and I can see if fuel pressure is available on it.
 
#3 ·
What are the symptoms?
There is a schrader valve on the right front side of the fuel rail (as seen from drivers position), where a mechanical fuel pressure indicator can be installed. But when fuel pressure is the problem, you most probably encounter low power during acceleration and low mpg.
 
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#4 ·
The truck cranks but doesn't start. The etc light comes on also the esp light. I changed the throttle body last year was having the same issue. Just started up again. Asked a couple of mechanic buddies and they say to check the fuel pressure maybe the filter or pump don't work
 
#5 ·
So it doesn´t start at all now? Do you hear the fuel pump for some 3 seconds when switching ignition to run? You can do a quick check for fuel, by pressing the schrader valve on the fuel rail. If fuel under reasonable pressure comes out, then the pump is not the problem. Keep a rag at the valve to catch any spills.
Did you check if there is any fault code set in the PCM?
 
#8 · (Edited)
It gives a failure of the secundary circuits of the coils, but i wonder if the primary circuit is monitored. I would check the fuses #6 and #16 in the PDC (feeding the ignition coils).
Also check fuse 24 on the junction block (feeding fuel pump and PCM).Regarding the fuel pump, the noise level is quite low and without engine running, it will only run for 3 seconds and be shut of by the PCM.
You can also swap the auto shutdown relay in the PDC with a similar relay in there, just for trouble shooting purposes.
The pages for faults 4 and 6 are not attached, but are probably for the coils D and F?
 
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