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Discussion Starter #1
I have an 07 6.7 that won't start. I checked the fuel pressure from the lift pump and it is good, around 9 psi, I am also getting fuel at the injectors, according to the scan tool I am getting around 1500 psi while I am cranking the truck. I replaced the cam sensor and it had no effect on it. Any other ideas? :banghead:
 

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I thought the pop pressure on CR injectors was in excess of 3ksi?
 

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Discussion Starter #3
I am not sure what the cranking pressure should be, but I thought I read on here somewhere that it should be around 1500. My scan tool reads in kpa so I converted it to psi.
 

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Discussion Starter #4
So, I unplugged the fca on the back of my cp3 and alll I get is code p0251, but no noticable fuel pressure increase, the truck still won't start. Any ideas?
 

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I believe you need alot more than 1500 PSI while cranking. Isnt it more like 4000-5000 PSI to start ? Youre losing pressure somewhere. Bad injector maybe? Unplugging the FCA should have let full pressure to the injectors , so maybe the FCA is bad, since it didnt raise the cranking Rail pressure.
 

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I have an 07 6.7 that won't start. I checked the fuel pressure from the lift pump and it is good, around 9 psi, I am also getting fuel at the injectors, according to the scan tool I am getting around 1500 psi while I am cranking the truck. I replaced the cam sensor and it had no effect on it. Any other ideas? :banghead:
Sounds like you may have one are more injectors returning fuel.I would check and see if you have a heavy amount of fuel returning and go from there.If you can clamp of the return line with some vise grips the truck will start if this is your problem.
 

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Discussion Starter #7
Thanks mikeshauling for the reply. Is there any way to test the fca, I don't want to start throwing parts at it. While cranking with the fca unplugged, the fuel pressure is fluctuating between 10,100kpa and 11,000kpa. With the fca plugged in, the fuel pressure fluctuates between 10,000kpa and 11,000kpa as well.
 

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Discussion Starter #9
Ok, so the fuel return line coming off of the fuel rail is steel and goes to a banjo fitting down at the filter housing where there is another banjo fitting and it tees into a line that is coming from the cp3. I squeezed the line between the cp3 and filter housing and it made absolutely no difference.
 

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Check the relief valve on the rail, it might be leaking or stuck open, had 1 today on an isc that was hard to start but running only had 10k psi when it wanted 17k psi. remove the return line off the valve and see if any fuel comes out while cranking, shouldnt have any.
 

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Ok, so the fuel return line coming off of the fuel rail is steel and goes to a banjo fitting down at the filter housing where there is another banjo fitting and it tees into a line that is coming from the cp3. I squeezed the line between the cp3 and filter housing and it made absolutely no difference.
The return i speak of is on the back of the head.
 

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Discussion Starter #13
Thanks supertech. I removed the line and it is dumping fuel out of it. I am guessing that is a bad thing. What is the best way to fix this problem?
 

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Discussion Starter #14
Carl Peters. it was just changed about 150 miles ago. I was driving home from work, about 15 miles, and was almost there when it just started running real bad. I made it home and it hasn't been right since.
 

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Carl Peters. it was just changed about 150 miles ago. I was driving home from work, about 15 miles, and was almost there when it just started running real bad. I made it home and it hasn't been right since.

You running a tuner?
 

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Thanks supertech. I removed the line and it is dumping fuel out of it. I am guessing that is a bad thing. What is the best way to fix this problem?
Let me make sure we understand each other, after removing the line from the relief valve on the rail and cranking, you should get fuel from the line, what you wanna check is if there is fuel coming out of the valve on the rail. The valve shouldnt leak anything, I think cummins spec is like 30 drops in 30 seconds but a good valve wont leak at all.
The fuel coming out of the line is return form the rest of the fuel system, the injectors return a small amount and so does the pump, but the valve is a protection valve to dump the pressure if the pressure gets too high for some reason, so it shouldnt leak anything unless pressure is close to 30k psi which you dont have. Let me know. If the valve is leaking, it's bad. Need to replace.
 

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Discussion Starter #19
Ok supertech, I think I got it right this time. I pulled the line off of the rail and cranked the engine over, no fuel came out of the valve, only the line.
 

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Discussion Starter #20
The worst part about this is that I have to be at work at 5:45 tomorrow evening so I need to sleep some tomorrow, and unless your in Dallas, nothing stays open late so you can get parts.
 
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