I am new to the site and am having trouble figuring out how to post. I have a problem and need some help. I have a 2002 LB7 I bought about 2 months ago. I have been getting trouble codes and working things off as I can. So far I have replaced all (8) injectors and the vacuum pump. I was getting a P0193 code and then my water pump started leaking. I tore it all apart and changed out the CP3 pump and the water pump. Its all back together and I got it to start but something is wrong. It makes a really loud noise at idle like the lifters are hitting. Seems like it is surging a little. Hard to explain in words. Sounds better if you give i a little throttle. Does anybody have any idea what I should do now? Could it be one of the connections maybe I didn't put i together right? Can somebody tell me how to post?
LB7: Won't Start After CP3 pump change out
- Thread starter daltongd
- Start date
You don't have the electric connector plugged in right, or you have a bad FPR.
When it sounds like rod knock at idle, yet cleans up when you rev it, the Fuel Pressure Regulator is not operating.
The FPR is on the passenger side of the CP3 towards the back. It has a black electric socket, IIRC it's straight out on the LB7 (90 deg on LLY and up)
When it sounds like rod knock at idle, yet cleans up when you rev it, the Fuel Pressure Regulator is not operating.
The FPR is on the passenger side of the CP3 towards the back. It has a black electric socket, IIRC it's straight out on the LB7 (90 deg on LLY and up)
PS- Welcome to Duramax Diesels. Keep your hands and feet inside the tram at all time, and please do not feed the animals.
PSS - Threads like this normally go in "Hard Parts".
But it does make me wonder if we need a HELP! forum area...
But it does make me wonder if we need a HELP! forum area...
Did you replace the CP3 with one off another LB7? I put an LBZ pump on my LB7 last year with an Arson kit to get a little more fuel. It will jack rail pressure up at idle and can even be enough to give you a High rail pressure code and it creates an awful "rattling" sound almost like a cummins engine. You can dial fuel pressure down with EFI live. If not, then X2 on what Mcrat said. FPR may not be operating properly...
x3 on the regulator. did you buy a new used cp3 or a new cp3. ?? it sounds exactly like the regulator. chances r the one on your old cp3 is good try swapping them out it is not impossible to do with cp3 still in the truck just a pain.
I purchased a rebuilt pump from Oregon fuel injector which is suppose to have a new FPR. It freezing cold this morning so once it warms up I plan to go check out the connection and see if I got it wrong. I think I can get to it without too much trouble. I sure hate to have to tear the engine back down. Getting all the fuel lines out of the way was a pain not to mention getting the pump out of the little valley its in. Thanks for you help and I will post what happens
I removed and reattached the connector to the regulator and tried it again. The problem is still there so now I know its not the connection. What a pain. Is it OK to start the engine without the ECM connected (side of radiator). Anyway thats the way I tested it.
When the FPR has no power, it goes to max pressure. This causes the fuel to enter the chamber too quickly, causing the knock, and when the engine tries to control the idle RPM, it freaks out, which causes the surging.
You can't start the engine with the ECM disconnected. You must have disconnected the TCM (Trans control).
You can't start the engine with the ECM disconnected. You must have disconnected the TCM (Trans control).
Unplug the FPR and stick an volt/ohm meter into the harness connector. You will need a couple paperclips or thin VOM leads. Switch it to DC volts, 12, and crank the engine. If you see no voltage, you have a problem further up the line.
Someone smarter than me would be required to tell you how many volts you should see when everything is OK with the signal. If you have the right signal, your FPR valve is probably bad.
Someone smarter than me would be required to tell you how many volts you should see when everything is OK with the signal. If you have the right signal, your FPR valve is probably bad.
I did the volt test. I was getting 10 volts with the ignition in the on position so I didn't try to start. Sounds like more rationale for he regular being the problem. Seems a little weird that a brand new regulator would be bad. I will give Oregon fuel injector a call tomorrow and talk to them about it. It's almost tore down enough to remove the pump. I will try to remove the regulator without removing the pump but I don't think it will work.
I pulled the regulator off and did a bench test using 12 volts. Both the old and the new act the same as far as I can tell. Both respond by activating the solenoid. Don't know if that's normal or not. I was wondering could it have been that I didn't make a good connection on the #1 and #2 fuel injector? Would it act the same?
I talked with Oregon Fuel Injector and the rep said I didn't have the gear torque onto the shaft at the proper value or I had a fuel leak or air problem. I pulled the pump and took the gear off. It didn't look like it was all the way on but it took a gear puller to take it off.
Any comments, do you think the shaft could be slipping around the gear and still need a puller to remove?
Any comments, do you think the shaft could be slipping around the gear and still need a puller to remove?
The FPR signal is not actually just straight DC voltage... Its a PWM signal (pulse width modulated). So, it switches on and off x-times per second (Hz). The voltage goes on and off instead of variable in increments.
During the change out you have to disconnect the #1 and #2 on one side and #5 and #6 on the other side. Other than the CP3 its one of the only things that got disconnected. It was connected when I disassembled the 2nd time. I guess what I was asking was If 2 cylinder were not connected would it make that same sound when running.
If the engine rattles badly and the idle hunts (surging) and sometimes dies, that mimics the behavior of an uncontrolled CP3.
You probably don't have a TechII, but if you have any way to look at the rail pressure at idle, it will tell you if the CP3 is to blame. IIRC, it's 30 Mpa pressure at idle.
Yes, I did know that the CP3 is PWM, but I also know if it's getting power (good wiring) it will show on a DC reading, I just don't remember what the normal #'s are. No voltage = bad wiring.
You probably don't have a TechII, but if you have any way to look at the rail pressure at idle, it will tell you if the CP3 is to blame. IIRC, it's 30 Mpa pressure at idle.
Yes, I did know that the CP3 is PWM, but I also know if it's getting power (good wiring) it will show on a DC reading, I just don't remember what the normal #'s are. No voltage = bad wiring.
Ok well I didn't do anything other than look at everything and put it back together. I did not find any smoking gun. This time I was very careful to make sure everything was right. Torqued the gear on per spec this time
Anyway its all back together now and its doing the same thing. Codes are 0088, 0102, and 0193.
The 0102 is because I don't have the air intake installed so the mass air sensor isn't reading any air.
I talked with Oregon fuel injector again and this time the guy says its either he rail pressure sensor or the regulator.
My code reader also had a bunch of weird codes come up like 484D, 5258, 5e64, 6a70, 767C, 8288 and on and on. Not sure what that was all about.
Looks like I need to take it all apart again and put in my old regulator to see if that's the problem. I should have done that last time.
Anyway its all back together now and its doing the same thing. Codes are 0088, 0102, and 0193.
The 0102 is because I don't have the air intake installed so the mass air sensor isn't reading any air.
I talked with Oregon fuel injector again and this time the guy says its either he rail pressure sensor or the regulator.
My code reader also had a bunch of weird codes come up like 484D, 5258, 5e64, 6a70, 767C, 8288 and on and on. Not sure what that was all about.
Looks like I need to take it all apart again and put in my old regulator to see if that's the problem. I should have done that last time.
My original code which made me decide o change out the pump was a P0193.
The reason I didn't change out the regular was that I talked to a diesel mechanic and he said sometimes you just have to let it run for a while to get all the air out. Well this time I let it run for a while and its still doing the same thing. I had my son pumping on the bleeder pump the whole time I was running the engine.
The reason I didn't change out the regular was that I talked to a diesel mechanic and he said sometimes you just have to let it run for a while to get all the air out. Well this time I let it run for a while and its still doing the same thing. I had my son pumping on the bleeder pump the whole time I was running the engine.