OK I have an lb7 was driving down the road blew a huge cloud of white smoke started fuel knock next day would not start figured it was injectors to it to dealer to test the guy said he could not check because truck was only building 600psi of fuel pressure and told me to check the return fuel rates so I did but there is no fuel coming out of return lines excpt the cp3 return so pulled a high pressure line off fuel rail and cranked and got a dribble out of it so then I pulled high pressure line off of the cp3 and got a dribble out of it so I was thinking the cp3 is bad but was told it sounds like something else but don't know what any suggestions would be greatly appreciated before I have just start guessing at parts
fuel problem need help
- Thread starter reeves_mck
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- fuel pressure lb7
Sounds like a bad cp3. Might be a bad regulator too. Check for leaks or kinks on your fuel lines.
Glad you made it over,could try to remove the return line running back to the tank and see if all you fuel is returning to the tank if it is the fprv could be stuck or bad after that i dont remember if you can see the cp3 gear turn thru the oil fill tube opening in the timing cover with the fill tube removed
OK ill see if I can check the cp3 gear I have every return line routed to dump the fuel into seperate containers and the only place fuel is coming from is the return on the cp3 . Is there a way to check the fprv?
super diesel
<<<< Under Pressure
With the high pressure line (the steel line with the hex cap) off the cp3 pump itself, it should shoot a stream about 5-7" high out of it when cranking with the reg unplugged. Some one correct me if they have seen more. If this is ok, then it may be a injector stuck wide open. You will need to pull the glow plugs to see which one blows more mist (fuel) out of when cranking it over. Unplug the injector harnesses when doing this (may be better to unplug the injection fuse instead though which is better) and leave the reg unplugged too. Check for fuel in the crankcase just for the fun of it and to rule it out. I don't see this being the problem with your description of white smoke coming out, and if it's coming out of the exhaust, if this is the case (sound to me like a injector stuck wide open with the fuel knock and low cp3 pressure which would dump fuel straight through thus the reason for low pressure and white smoke is usually caused from raw diesel fuel in this case).
Yes. you can see the cp3 gear through the oil fill hole if it's removed.
Yes. you can see the cp3 gear through the oil fill hole if it's removed.
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super diesel
<<<< Under Pressure
Yes. Turn the truck on and go to the reg plug on the cp3. Unplug it and listen if you hear the humming stop. you may hear a very slight click sound from the slide inside of it slap to the back of the reg. When you plug it back in the humming should continue. You should have gotten some other problems related to this though if it is a problem. If it's stuck, it will either make high rail pressure at a stop and lope or it would not lit the truck rev up very far and feel as though it was running out of fuel. But it would certainly build more than 600psi at idle when cranking though on either case.
OK well I checked the cp3 gear it is turning and looks fine unhooked the fprv and the humming stopped plugged it back and could hear the humming again cranked it got about an inch of fuel to come out of the cp3 high pressue line unhooked the fprv cranked it again and got about an inch of fuel to shoot out of the cp3 so what are your suggestions at this point should i still pull the glow pluggs and check for the fuel mist in each cylinder?
super diesel
<<<< Under Pressure
I don't like the sound of it belching white smoke out. If it's the cp3 loosing pressure, I wouldn't believe you would see the white smoke. I also don't like saying it and I know it's a pain, but, yes. You will need to know which one is stuck open if this is the case.
OK well I did find the injector that's stuck open thank you all for the advice I have never heard of some of the test that you guys had suggested and I appreciate no one else could help im glad i was reffered to this site from blk smoke lb7 I will be replacing it and let you guys know if it fixes it thank you
Thanks for the help Michael :thumb:
To the op you are very welcome,ive been there and been lost and had people give me a helping hand so any time i can help i will.Let us know how it turns out
To the op you are very welcome,ive been there and been lost and had people give me a helping hand so any time i can help i will.Let us know how it turns out
super diesel
<<<< Under Pressure
OK gents well I got the new injector in fired right but still has a little knock and is pouring white smoke out of exhaust let it run for a couple mins shut it off and saw about a gallon of diesel pour out of exhaust pipe I did crank it over a few times with the ing 1 fuse out I'm not sure how to go about this any suggestions please
Sounds like you still have one or more injectors hung open. Do you have Efi Live or access to a tech2 to check the balance rates?