Bad Regulator?

[IdahoRob]

I've got a friend with a LB7 built engine running twin cp3's. Truck is throwing a P0089. The desired rail pressure is 6000 at idle and the actual is 18,000+/-. As soon as the truck comes off idle, the actual comes down to meet and run with desired.

I don't have any experience with bad regulators,

Thoughts?

Thanks,
Rob

 

[Kat]

It could also be a bad CP3 controller IIRC

 

[DrededSS]

Thanks for posting Rob.

I followed the wires the best I could to make sure none were exposed or cut. Everything under the hood looked fine. Where is the CP3 controller?

 

[sweetdiesel]

Bad ground,Bad fuse?

bad regulator?

can you turn off the lift pump?If so try that and see if that effects it

worst case adjust regulator current

 

[sweetdiesel]

I actually put a regulator in my 2nd cp3 that had no guts in it! full powa

 

[DrededSS]

Put almost 6k miles on it with no trouble until now. It ramps up to 26,000 psi under throttle. There is an electrical "surge" at idle. I just figured my alternator needed replacement. It will cycle similar to when the a/c is running. But that surge doesn't seem to affect the idle rail pressure.

I'll try the lift pump kill.

 

[DrededSS]

Might be a dumb question, but can I kill the FASS power and get any fuel up to the CP3s? I do not have any of the stock fuel system left under the truck, and the stock filter and housing have been removed. It's just the FASS pulling from the tank, then directly to the CP3s.

 

[sweetdiesel]

Put almost 6k miles on it with no trouble until now. It ramps up to 26,000 psi under throttle. There is an electrical "surge" at idle. I just figured my alternator needed replacement. It will cycle similar to when the a/c is running. But that surge doesn't seem to affect the idle rail pressure.

I'll try the lift pump kill.

Electrical surge? Have you checked your fuse?

 

[DrededSS]

Electrical surge? Have you checked your fuse?

Fuse where the FASS is powered looks fine. What others should I be checking? I'm about to record a little video of the surge. Not sure how that would make the CP3 run weird though.

 

[DrededSS]

Here is a little video of the voltage at idle. If you can listen past the chatter of the engine, you will hear a surging growl. That sound is new too and actually drowns out the sound of my FASS pump. It's coming from under the hood. BTW, these are 2 week old Optima red tops. This video only has one of the surges, but it does it in park, neutral and drive.

 

[slowlmm]

Ats or ppe cp3s? you could try unhooking your fass to see if tht helps. sometimes to much psi at idle will cause a surge. u can also unhook the 2nd cp3 and it should lope bad back and forth tht should confirm tht the cp3 controller os working

 

[sweetdiesel]

Fuse where the FASS is powered looks fine. What others should I be checking? I'm about to record a little video of the surge. Not sure how that would make the CP3 run weird though.

pending the install but on your lil red + battery box thingy there should be a fusible link with a IIRC 10amp fuse.....just a thought

 

[DrededSS]

Ats or ppe cp3s? you could try unhooking your fass to see if tht helps. sometimes to much psi at idle will cause a surge. u can also unhook the 2nd cp3 and it should lope bad back and forth tht should confirm tht the cp3 controller os working

PPE CP3s.

 

[sweetdiesel]

Here is a little video of the voltage at idle. If you can listen past the chatter of the engine, you will hear a surging growl. That sound is new too and actually drowns out the sound of my FASS pump. It's coming from under the hood. BTW, these are 2 week old Optima red tops. This video only has one of the surges, but it does it in park, neutral and drive.

hard to tell sounds like downpipe is rubbing almost?

rail press is bouncing?

 

[DrededSS]

Rail pressure is steady around 18k psi. That growl surge is consistent with the engine rpms surging about 100 rpm.

The voltage surge doesn't seem to affect the rail pressure though.

It's tough to hear anything with 5 inch exhaust up to 8" stacks

 

[sweetdiesel]

it's tough to hear anything with 5 inch exhaust up to 8" stacks

yes it is:d

 

[McRat]

Check the voltage being fed the second CP3. If it's zero at idle, the controller is not working and it's going full blast.

I believe you can feed it 12v safely to test briefly, but I don't know what the normal operating voltage is. In any case, use a fuse (3amp) if you test it. When you apply the voltage, the pump should ceise pumping much fuel.

 

[DrededSS]

Check the voltage being fed the second CP3. If it's zero at idle, the controller is not working and it's going full blast.

I believe you can feed it 12v safely to test briefly, but I don't know what the normal operating voltage is. In any case, use a fuse (3amp) if you test it. When you apply the voltage, the pump should ceise pumping much fuel.

Just pull the connector at the CP3 and stick a meter to it with the truck running?

 

[McRat]

Just pull the connector at the CP3 and stick a meter to it with the truck running?

Yup. Normal diagnosis to isolate is to start the engine, then pull the connector. It should suddenly start idling like crap and loping. To see if it's the controller or regulator, check the voltage at the connector. It should be fairly high, IIRC, 10-12v? To check the regulator, apply voltage to it and see if it goes quiet.

I haven't hurt anything yet by doing testing that way. But I hate to say nothing could happen just because I haven't seen it.

When I did my comparison testing on different CP3's, I ran the engine perhaps 1 hour with the CP3 unplugged, in 5 minute intervals.

 

[IdahoRob]

Good point Pat. If the idle does not change when the 2nd cp3 regulator connector is pulled, then that is the one with problems, and vise-versa. Lee, you can unplug the cp3 that is in the stock location easily. There is a connector right behind the oil fill to check that one.