LLY Issue's...Need Advice

[bullfrogjohnson]

I have been working on a buddies truck. Its an 05 with 130k on it, edge juice, intake and exhaust. The truck has been falling on its face so I logged it. Rail was dropping down to 9-10k @ WOT. Did a bottle test and the FPRV was leaking. I shimmed the valve and noticed a lot of fuel on the valve cover around #6 injector. The #6 HP line ended up being cracked. So after shimming the FPRV and replacing the line the truck would hold 26k using DVT.

Well he called me later that day and said the truck is still falling on its face. Logged it again and it still is dropping to 9-10k rail pressure. I did another bottle test to make sure and everything was fine. I am starting to think the CP3 is going out, but for grins I checked the balance rates and the #4 and #2 injectors were -5/-6.

I know on the LB7's, high fuel return rates will drain the rail but am not sure on the LLY's. What test(s) can I run to determine whether its the CP3 or the injectors?

Also this truck has abnormally high oil pressure 110-115 psi @ idle and pegs the sensor @ 129 psi while driving. Owner says its always had high pressure since he has owned it at 60k.

 

[sparepartsracing]

never seen that kind of oil pressure in my life...i was wondering hwy they made the guage go to 120 i guess for people like him

except for sti's and to 4 banger they run 120psi+

 

[TNRGreene]

High returns can & will affect LLY's too
Did you log OP or just look at the gauge. If you can figure out how to get me better OP I'd like to know

 

[Akdiesel]

Agreed my LLY runs 28 or so psi at idle and 60 cruising...but I also seem to have a pretty strong motor/fuel system so maybe I'm lucky?

 

[paint94979]

Agreed my LLY runs 28 or so psi at idle and 60 cruising...but I also seem to have a pretty strong motor/fuel system so maybe I'm lucky?

Mine is the exact same 28/60

 

[bullfrogjohnson]

Mine is the exact same 28/60

Mine is the same way on my truck. But his logs that high.

 

[Akdiesel]

His logs that high but what's the cluster gauge read? Also it may sound stupid but have you guys tried a new oil pressure sensor...one would think that high of Op would cause other issues

 

[bullfrogjohnson]

His logs that high but what's the cluster gauge read? Also it may sound stupid but have you guys tried a new oil pressure sensor...one would think that high of Op would cause other issues

his gauge reads right along with the log.

I also thought this was strange that even with all the fuel issues this trucks has had it has never thrown a single rail pressure code.

 

[wes06dmax]

Could it be a bad fuel regulater just throwing ideas out here

 

[wes06dmax]

Well bad fuel regulater usally makes have to much fuel right

 

[bullfrogjohnson]

Could it be a bad fuel regulater just throwing ideas out here

I had thought about it but the truck holds 26k with DVT and follows desired rail until he floors it and the rail drops to 9-10k.

How do you do a fuel injector return test on a LLY?

 

[wes06dmax]

Could it be a dirty fuel filter

 

[Akdiesel]

The oil pressure thing is weird too...my truck would at least throw the P1093 and do the same thing as you're saying with the drop in rail psi...what I think is since there's no load on the motor using the DVT function to ramp up fuel psi it isn't as accurate as it could be. Just my opinion and I've been wrong before :rofl:

 

[TQMONSTR]

Agreed my LLY runs 28 or so psi at idle and 60 cruising...but I also seem to have a pretty strong motor/fuel system so maybe I'm lucky?

at what speed do you cruise at?

 

[sweetdiesel]

Could it be a bad wire harness perhaps check the wires around the ficm on the top bracket

I talk to Ted about this tommorow, as far as the oil press logging would probably show the same unless the actual cluster is screwed you could check the oil press with a seperate gauge and just go in the oil gallery

if it truly was that high you would have issues with oil filters like I do if it is that high something could be wrong with the relief valve

 

[GMC_2002_Dmax]

Temporarily put the CP3 power wire on a switch, go WOT and then after a few seconds interrupt power to the CP3 with the switch, if the pressure jumps up significantly it could be a faulty regulator, if it still stays in the tank then I suspect the CP3 might be a POS.

 

[Stingpuller]

Cp3

the last one I had in the shop like that was a bad CP3 pump. It would go 140 to 150 mpa and as soon as you hit the pedal it would drop to 9/10 k. It was a bad pump. Jeff

 

[skintback]

Dose it have a lift pump what vacuum/psi are you seeing have you taken the edge off and tried it?

 

[Akdiesel]

at what speed do you cruise at?

70-75

 

[bullfrogjohnson]

Dose it have a lift pump what vacuum/psi are you seeing have you taken the edge off and tried it?

No lift pump. I removed the edge completely and the truck still falls on its face.

Also has new fuel filter.