• Welcome to The Truck Stop! We see you haven't REGISTERED yet.

    Your truck knowledge is missing!
    • Registration is FREE , all we need is your birthday and email. (We don't share ANY data with ANYONE)
    • We have tons of knowledge here for your diesel truck!
    • Post your own topics and reply to existing threads to help others out!
    • NO ADS! The site is fully functional and ad free!
    CLICK HERE TO REGISTER!

    Problems registering? Click here to contact us!

    Already registered, but need a PASSWORD RESET? CLICK HERE TO RESET YOUR PASSWORD!

2004 Yukon XL 2500 LBZ

BigDogYJ

Well-Known Member
Messages
475
Reaction score
380
Location
Kommifornia
So I got the new PSC 6 bolt gear box installed 2 weeks ago. Along with new rare parts pitman and idler arms (removed cognito pitman idler support kit as suggested by rare parts), lower steering shaft, intermediate steering shaft, lower steering column bearing, 2011 hydroboost, and merchant automotive PS lines. I should have done the PSC pump while I was in there but oh well. I’ll get to that eventually.
First of all, dead spot is 100% eliminated got alignment done and it tracks beautifully. My main issue has been getting all the air bled out. It took quite a while, apparently blending the hydroboost systems can take some time. The stock pump started making noise I think I’ve got all the air out but occasionally I hear a little noise from the pump (new PSC pump arrived today). We drove up to the Oregon coast for Labor Day weekend and the truck drove perfectly towing the trailer. So much better than the first time. That dead spot in the steering was not pleasant. Hopefully this PSC box and pump last a good long while. Oh I also bled the system with Swepco 715 fluid per PSC recommendation.
 

BigDogYJ

Well-Known Member
Messages
475
Reaction score
380
Location
Kommifornia
So the past few trips with the travel trailer have netted about 11 mpg. Keep in mind that’s with a fair amount of grades and I’m pretty heavy on the pedal going up. I maintain 60-65 mph. The trailer is about 8500lb / 1250 tongue weight. So on the upper end of 12-15%. Still adjusting the WD spring bars to find the sweet spot. Generally rides great, sometimes can be a little bumpy but CA roads suck. Super happy with the ProPride hitch and it definitely does its job.
 

BigDogYJ

Well-Known Member
Messages
475
Reaction score
380
Location
Kommifornia
I can’t believe I forgot to report that I did set a P0087 code and limped to no more than 2k rpms. I had just passed a semi going up a grade and let off the throttle a bit. Then laid back into it and had no power. A few seconds later noticed the CEL. crap….
pulled over to the shoulder and shut it off, restarted, CEL still on and wouldn’t rev over 2k. I was able to limp it the 1.2 miles to the exit I was planning to get off to get fuel. Got to the truck stop and filled up 34 gallons. Truck holds 37. Filled up, cleared the code and hit the road. Laid into it pretty good getting back on the highway and never had any other problems.

im pretty sure i ran the fuel level too low, the FASS sucked air, I know it won’t let air pass through, so I guess it just limited fuel to the engine hence the loss of rail pressure.
anyways, that’s all. Just couldn’t believe I forgot to have that in my previous report.
 

JayTheCPA

Well-Known Member
Messages
2,182
Reaction score
2,322
Location
Annapolis, MD
Still adjusting the WD spring bars to find the sweet spot.
You will know that the bars have gone past the sweet spot when the truck wants to shoulder into a curve.

Scenario: rolling down the highway, enter a curve rated for the highway speed, and you feel the opposite front corner (ie: if a curve to the right, then the truck's left front) will feel like it is dipping down into the road.

When you feel the shouldering effect, back off the bars a bit, verify that the shouldering is gone, and the rig is set.
 

Will L.

Well-Known Member
Messages
14,071
Reaction score
20,977
Location
Boulder City Nv
I can’t believe I forgot to report that I did set a P0087 code and limped to no more than 2k rpms. I had just passed a semi going up a grade and let off the throttle a bit. Then laid back into it and had no power. A few seconds later noticed the CEL. crap….
pulled over to the shoulder and shut it off, restarted, CEL still on and wouldn’t rev over 2k. I was able to limp it the 1.2 miles to the exit I was planning to get off to get fuel. Got to the truck stop and filled up 34 gallons. Truck holds 37. Filled up, cleared the code and hit the road. Laid into it pretty good getting back on the highway and never had any other problems.

im pretty sure i ran the fuel level too low, the FASS sucked air, I know it won’t let air pass through, so I guess it just limited fuel to the engine hence the loss of rail pressure.
anyways, that’s all. Just couldn’t believe I forgot to have that in my previous report.
Did you see any change in fuel pressure from the Fass spiny thing to the gm spiny thing?
That would confirm your theory, but no pressure drop would mean that is wrong.
 

BigDogYJ

Well-Known Member
Messages
475
Reaction score
380
Location
Kommifornia
You will know that the bars have gone past the sweet spot when the truck wants to shoulder into a curve.

Scenario: rolling down the highway, enter a curve rated for the highway speed, and you feel the opposite front corner (ie: if a curve to the right, then the truck's left front) will feel like it is dipping down into the road.

When you feel the shouldering effect, back off the bars a bit, verify that the shouldering is gone, and the rig is set.
Interesting. I’ll try to follow this next time I hook up and see how it works out. Thank you.
 

BigDogYJ

Well-Known Member
Messages
475
Reaction score
380
Location
Kommifornia
I think @Will L. is asking if you saw a change in fuel pressure between lift pumps at the IP with the change. At least that's my interpretation of his comment.
Ahhh ok. Ya know I’m not certain of fuel pressure going to the injection pump. I’ve never put a gauge on that side of things. I know there’s a port on the FASS to read this but I haven’t done anything with it yet. I know that actual and desired rail pressures are dead on. Especially since I put the new cp3 in at 90k.
 

btfarm

America First!
Staff member
Lead Moderator
Messages
18,363
Reaction score
6,974
Location
Sandwich, Illinois
The Duramax does not have a lift pump in OEM trim except the Vans. It's a good idea to add one but not necessary. I drove my LBZ 355k without one and had few problems. And that's with a higher performance tune over stock.
Based on your experience I'm certain you are correct in blaming it on a starved FASS pump pickup.
 

Will L.

Well-Known Member
Messages
14,071
Reaction score
20,977
Location
Boulder City Nv
The Duramax does not have a lift pump in OEM trim except the Vans. It's a good idea to add one but not necessary. I drove my LBZ 355k without one and had few problems. And that's with a higher performance tune over stock.
Based on your experience I'm certain you are correct in blaming it on a starved FASS pump pickup.
The quality of fuel is a big part of the success or failure. How prime the crude is, and how many longer chain counts are has a big effect. Higher ethanol rates allow more water through and faster wear. But you can have high ethanol if the water intrusion is kept under good control. Also the ethanol is thinner than the diesel. So the issues that happen under vacuum like aeration is more exaggerated.

The consistency of fuel is so far away from where it used to be in the 80’s and early 90’s, and individual states been setting laws on fuel since then making it more different.
Most people never notice difference in fuel because the computer makes the adjustments. But the difference in longevity shows up. Out here, like 85% of fleets that run diesel pickups add a lift pump. It usually pays off with our fuel, especially Ca fuel it pays off. They have the fuels so stripped for emissions that the next step would be wet sandpaper! Haha
 

BigDogYJ

Well-Known Member
Messages
475
Reaction score
380
Location
Kommifornia
The quality of fuel is a big part of the success or failure. How prime the crude is, and how many longer chain counts are has a big effect. Higher ethanol rates allow more water through and faster wear. But you can have high ethanol if the water intrusion is kept under good control. Also the ethanol is thinner than the diesel. So the issues that happen under vacuum like aeration is more exaggerated.

The consistency of fuel is so far away from where it used to be in the 80’s and early 90’s, and individual states been setting laws on fuel since then making it more different.
Most people never notice difference in fuel because the computer makes the adjustments. But the difference in longevity shows up. Out here, like 85% of fleets that run diesel pickups add a lift pump. It usually pays off with our fuel, especially Ca fuel it pays off. They have the fuels so stripped for emissions that the next step would be wet sandpaper! Haha
Agreed. Hence why after I lost the CP3 and it trashed the injectors at 90k, I decided to go with the FASS to protect those expensive components from certain death again. I also usually run Stanadyne performance formula year round to separate the water so the FASS can do its job. Some additives emulisfy the water in the fuel which seems like a step backwards, even though I believe the FASS would still do its job, why make it work harder if not necessary.

I think it was just the FASS getting starved of fuel and doing its job. I've had that FASS for more than 9 years now and its still running perfect. I spoke with FASS recently about upgrading to a smaller unit since I don't run a very heavy tune, they called mine a dinosaur and that they just keep running. Guess I'll keep it running till it quits. Gotta love good ole' reliability.
 
Last edited:

THEFERMANATOR

FRANKENBURBAN
Staff member
Lead Moderator
Messages
10,392
Reaction score
5,127
Location
ZEPHYRHILLS FL
The Duramax does not have a lift pump in OEM trim except the Vans. It's a good idea to add one but not necessary. I drove my LBZ 355k without one and had few problems. And that's with a higher performance tune over stock.
Based on your experience I'm certain you are correct in blaming it on a starved FASS pump pickup.
Partly correct. The vans up to 16 used a prime pump, but it did not run all the time. The van pumps have a bypass built in to them that opens when the pump shuts off after 60-90 seconds of priming after key on. The L5P and newer DOES have an electric lift pump as the Delphi high pressure pump Does not have a gear driven lift pump on the back of the pump like all 01-16's had.
 

BigDogYJ

Well-Known Member
Messages
475
Reaction score
380
Location
Kommifornia
Steering is still dialed in perfect with the new box. The 2011 hydro boost is friggin awesome. The pedal feel makes the truck feel like a new truck. I haven’t had a chance to change pump yet, had a few things come up family members moving and then having to replace a roof on the family cabin before the rain/snow starts. I should have some time over the next few weeks to get that changed out and do a fluid change on the trans, tcase, and rear diff as they are due. So far truck still drives like a dream and gettin put to work. Pulled a 10k dump trailer 300 miles a couple weeks ago with all the roofing we tore off. I really enjoy the benefits of a big suv and the seating for 8 while being able to pull relatively heavy trailers for work or play. Best combination for my needs. I’ll post up after I get the pump swapped.
 
Top