For testing, What should I see if the regular is unplugged. I think it is bad so I am looking for ways to troubleshoot it????? Anyone have a suggestion?

 

if you unplug the regulator the rail pressure should jump up to 23kpsi

 

And if the regulator is bad... Then it should drop or stay the same at a low pressure?

 

160k on the truck the pump could be bad, but the regulator can have trash in it, if you have time you can pull it out and clean it up but its a tedious job to take apart a regulator

 

I am taking one off a friends truck and gonna try it on mine today. Wish me luck the problem is the regulator and not the PUMP!!!! Ill save $500 bucks if the regulator fixes it!!!! Ill let you know what i come up with...

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Well it did not fix it. But it seems to be better. I am going to check everything again with the Tech II again and see if it's getting the pressure that it asks for.

 

 

Okay, I checked it again with a Tech II and the same result. Okay...I have just yesterday put a Regulator on the CP3 pump. (Took about 1 1/2 hours) What else is there to check? What about the valve at the end of the fuel rail on the drivers side? What is it called and how can I check it?or would it even be a possibility that it might be dropping the pressure. Again now this is the testing that I have done: With the Tech II connected, IN park it will build up to around 15000psi. Then driving: when desired reaches 17k 18k 20k, and higher the actual will drop to 3k or so... Am I missing anything before I spend the money and the time to put a new reman CP3 pump on it? Somebody help a fella out!!!!!

 

The valve your thinking of is the fuel rail pressure relief valve, and on the lb7's its on on the back of the rail, its on the fuel junction block.

https://www.dieselbombers.com/lb7-bo...-shim-mod.html

 

What do you think is the problem and how can I check the relief valve at the back of the rail?

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I read your write up on the leak LB7 FPRV and seen the pics thanks for that!!! But do you think I am loosing the pressure on the rails threw the FPRV or do you think the pump can build 15k psi and then just drop all the way to 3k psi all at once. I just have never seen a pump build that kind of pressure and all the sudden drop like that. and if I watch the Tech II real close, when I let off the peddle the pressure will jump up from 3k to like 15k and then back down to the desired psi. I really need some help on this. I dont want to do all that work and spend all the money to replace the pump and it be something like the FPRV. Should I cap it off or just ad the washers to it?