Author Topic: Lb7 fuel issue (Read 5985 times)

longball · « **on:** January 02, 2021, 10:35:36 PM »

Back in the summer I bought a 2004 LB7 from a coworker. 192k miles now and had new injectors fall of 2018 at roughly 185k miles (reputable, local, diesel shop). When I bought it there was a barely noticeable surge at idle. Fast forward to the morning following the first sub freezing night of the year and I had some white smoke on startup that lasted until I took off. No smoke after its warm or at stoplights like my other LB7 when the injectors went out. Throughout that first cold snap the surge got worse and it started surging while coasting to a stop. I ran a dose of HotShot secret though it with my usual XDP additive then changed the fuel filter and the symptoms went away. Today when changing oil I drained more than 2.5 gallons out of it. I having trouble understanding how it made enough oil to be obvious when draining it but I haven't had any white smoke for over a week now. Does it sound to y'all like a fpr problem or are the new injectors taking a dump? Trying to prepare myself before I have a chance to get the balance rates checked.

TexasRedNeck · « **Reply #1 on:** January 03, 2021, 08:31:14 AM »

I don’t think FPR would cause it to make oil.

Usually it’s the injector body cracking or a line leaking

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longball · « **Reply #2 on:** January 04, 2021, 01:58:16 PM »

Cant read return rates on this device and these readings were near operating temp.

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longball · « **Reply #3 on:** January 05, 2021, 12:41:35 PM »

After doing som reading I believe Tex is correct and there is an injector body cracked. It makes sense that a problem like that wouldn’t show up on balance rates. I’m wondering if it will show on return rates?

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KensAuto · « **Reply #4 on:** January 06, 2021, 09:39:44 AM »

I'm going with a line connection at the injector, but only if you're 1000% sure it's making oil.

longball · « **Reply #5 on:** January 06, 2021, 01:27:25 PM »

I’m sure. When I pulled the plug it was under pressure. Made a hug mess in the floor. I drained my 16qt catch pan before I started and and it was full after i drained everything out of the truck. Poured the contents of the catch pan in a 5 gallon bucket and it filled it to roughly 5” from the top.

Is there a way for a shop to diagnose which side of the motor it’s on or do they just have a 50/50 chance of guessing correctly?

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KensAuto · « **Reply #6 on:** January 06, 2021, 04:53:10 PM »

Lets say it's a cracked housing or bad copper return line washer. Either way I would want to look at both sides. If it's a washer, they all should be done.

6 or 7 years ago I had one in here for that issue. Another shop replaced injectors. It was burning coolant AND making fuel. They had reused the return washers, and used silicone to "glue" one of the cups in.

I don't work on that many dmaxes, but seems like I sure end up with the crappy ones.

longball · « **Reply #7 on:** February 22, 2021, 02:23:24 PM »

I had a shop tear into the truck and reseal all of the lines. I’ve put maybe 1,500 miles on it since. I can’t be sure but the oil level does seem to be creeping up slightly. I’ll keep an eye on it and see what happens. It also still has a slight surge at idle and when on a long, steady grade, I can feel it surge a little. After the shop worked on it it did stop smoking at startup, and starts quickly (as it always has). The shop owner did say that if they have to tear into it again he’ll do the labor for free, which I feel is pretty good of him.

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JR · « **Reply #8 on:** February 24, 2021, 01:13:04 AM »

Do you have a lift pump? That could be the surge.

Unless it make lots of oil, is it worth the trouble? At least the shop is standing behind the work and the LB7 injectors are way easier to work on.

TexasRedNeck · « **Reply #9 on:** February 24, 2021, 07:00:02 AM »

You might look at the voltage meter. My alternator was fluctuating between 14-16 volts and that was causing some surging in sync with the voltage surge but I noticed it mostly at idle. Replaced the alternator and surge was gone.

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longball · « **Reply #10 on:** February 24, 2021, 08:48:14 AM »

Quote from: JR on February 24, 2021, 01:13:04 AM

Do you have a lift pump? That could be the surge.

Unless it make lots of oil, is it worth the trouble? At least the shop is standing behind the work and the LB7 injectors are way easier to work on.

No lift pump. I don’t think any amount of fuel in the oil would be good and since he offered the labor I’ll try to get it fixed. That, and the surging is one of those things that will drive me bat Schiff crazy.

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JR · « **Reply #11 on:** February 24, 2021, 02:03:35 PM »

Lift could help with the surging and keep the CP3 happy.

longball · « **Reply #12 on:** February 24, 2021, 07:07:44 PM »

Quote from: TexasRedNeck on February 24, 2021, 07:00:02 AM

You might look at the voltage meter. My alternator was fluctuating between 14-16 volts and that was causing some surging in sync with the voltage surge but I noticed it mostly at idle. Replaced the alternator and surge was gone.

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The voltage on the dash holds steady. Out of curiosity I unplugged the alternator and started it. The surge seemed to lessen with it unplugged. I’ll have it tested and check the idlers and tensioner.

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JR · « **Reply #13 on:** February 24, 2021, 10:18:47 PM »

It won't get to a smooth voltage output till you get a few minutes of RPM on the alt. That might be part of the idle surge.

longball · « **Reply #14 on:** February 24, 2021, 10:40:28 PM »

Quote from: JR on February 24, 2021, 10:18:47 PM

It won't get to a smooth voltage output till you get a few minutes of RPM on the alt. That might be part of the idle surge.

Can you say that again but as if you’re talking to a 8 year old child? I don’t know much about anything, but I know even less about electricity.

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JR · « **Reply #15 on:** February 24, 2021, 11:14:17 PM »

No biggie, these trucks now are common high pressure rail injection. The injectors get the signal via electricity. An alternator will not fully start to charge putting out the voltage and amps required (about 14v) until the motor has run a little, usually over 1000rpm for a few moments, it will not do that right at startup.

Our injectors use multiple pulses to make these engines run smooth. Sure the CP3 is giving you mechanical high pressure, but the injectors control the pulses (multiple pulses make the engine run smoother/quieter) but it requires full voltage which may not occur until the truck runs a little.

The CP3 sucks fuel from the tank which may not be solid (air bubbles) when first started. Using a lift pump helps with this and prolongs the CP3 life and can make the engine run smoother as it doesn't have to work as hard since it is just making pressure not sucking too. If you have little bubbles or air in the system the lift can help big with those too. Note, ALL diesel truck now have lift pumps from the factory, they are learning. CP3 also has an electronic pressure Reg and a relief valve that can mess up too. I just replaced both my relief valve and lift pump. Valve was soft (mechanical) and the lift had stopped working. I have 210000mi on the truck now and I run Wally 2 stroke oil in the fuel (1/2oz per gal) or biofuel sometimes. I also run a 10mic filter at the lift pump and a 2mic filter in the stock location. Just had the tranny built too (to 700hp) and rarely push it hard, but have my moments.

Now Ken or Sean (or anyone else) may know more than me but think this is very close to how it all works. Remember I am just a old retired cop who reads a lot.

KensAuto · « **Reply #16 on:** February 25, 2021, 07:58:05 PM »

Pretty dang smart for an old guy.^^^

longball · « **Reply #17 on:** March 16, 2021, 10:51:40 PM »

I never thanked you for the explanation JR, so, thank you. For the first time in weeks I got my parking spot at home back so I’ll check the oil again in the morning. As of last week, it didn’t appear to be making oil, so I’m hoping this issue is behind me.

On to the steering parts now. Moog HD pitman arm and Rare Parts tie rods showed up yesterday. This morning, in spite of the Napa employees’ best efforts, I bought a new power steering pump and all associated lines. Idler arm and brace should be here Thursday. Once all that goes on I have a set of 285/75/17 Falken Wildpeak AT3W tires in the garage put on and hopefully be done spending money on this thing for a while. The 285/75/17 are 33.9” tall. Relocating the parking brake cable in conjunction with the Ranch Hand bumper should allow enough room for them to fit.

Everybody likes pictures right?

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JR · « **Reply #18 on:** March 16, 2021, 11:23:29 PM »

Nice size tires. To bad you aren't closer, I just got a mounting and balance machine.

You MAY have to do the fender mod with those tires, real easy on youtube (even Don could do it).

Did you get a lift pump?

longball · « **Reply #19 on:** March 16, 2021, 11:40:14 PM »

Quote from: JR on March 16, 2021, 11:23:29 PM

Nice size tires. To bad you aren't closer, I just got a mounting and balance machine.

You MAY have to do the fender mod with those tires, real easy on youtube (even Don could do it).

Did you get a lift pump?

If I was closer I’d definitely let you have a go at it. I have zero faith in most of our local tire shops.

I’ve been told there’s a parking brake cable behind the fender liner that will give an extra couple inches by moving it back some. If that’s not enough I’ll mod the fender.

I haven’t gotten a lift pump yet but I will. If I don’t stop writing checks for a while I’ll have to defend myself.

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JR · « **Reply #20 on:** March 16, 2021, 11:51:43 PM »

The brake line is no real issue, its behind the fender. Mod is super easy, hardest part is sealing it for rust.

You can do the pump cheap with the carter and a generic filter head ($150 total). Hardest part is the wiring and hose.

Put some HD tie rods on there. When I do my lift I will give you my napa lifetimes with sleeves.

Curious, on your rear springs do the springs sit on the overloads? Mine do (210k), but am getting deavers and adding bags.

longball · « **Reply #21 on:** March 22, 2021, 08:05:14 PM »

I will have to do the fender mod. They don’t rub much but I’ll beat on the fender to keep from turning the torsion bars. A 34” tire under factory height suspension should work fairly well for something we take on family trips and I drive every day.

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JR · « **Reply #22 on:** March 22, 2021, 08:25:05 PM »

https://youtu.be/SzEES8b-7IM

longball · « **Reply #23 on:** March 24, 2021, 07:58:28 PM »

Thanks for the video link JR. I started there then watched a few different ones before doing it. It hurt a little to beat on this thing with a 2lb sledge but it’s done.

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JR · « **Reply #24 on:** March 24, 2021, 08:11:41 PM »

At least you hit it where no one sees it. I painted mine then covered it all in undercoating making sure crud could still drain.

I'm running 35s like that. Maybe 3in lift by a few turns on the bars with with upper A arms.

Glad it worked is the main thing.

longball · « **Reply #25 on:** March 25, 2021, 09:29:30 PM »

I need to replace upper control arms soon so I may do a little something different then.
Measuring from hub to fender the truck has less than 1/2” of rake but the cv shafts are still flat. When I put the aftermarket (Kryptonite) control arms on I may add a little preload to the torsion bars and a very small block on the rear. When I say a little I mean 1” at the absolute maximum.

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longball · « **Reply #26 on:** August 20, 2021, 01:41:19 PM »

Good afternoon gents. Since going through the front end of this truck back in March I’ve replaced the pump once due to a noise I thought was a sign of it going bad. When I turn the noise is similar to the sound of the cooling fan when you first start up and take off, but louder. I also cannot turn the wheel while stopped and if getting on the brakes hard there is feedback in the pedal. The symptoms didn’t go away with the new pump and yesterday, while my wife was driving it she got a service brake system message. So all of the hard steering parts are new, the power steering pump is new, all of the lines are new, and the hydro is just over a year old. While looking at a buddy’s truck yesterday I noticed that his line from the pump to the hydro does not have the sharp bend in it that mine does. That got me to thinking that maybe I got the wrong line, and that extra restriction is causing these issues. If any of y’all are still driving an LB7/LLY/LBZ would you mind posting a picture of this line please?

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Sammconn · « **Reply #27 on:** August 20, 2021, 02:02:12 PM »

I’ll get some up close and personals tonight from my two.

longball · « **Reply #28 on:** August 20, 2021, 02:02:58 PM »

Quote from: Sammconn on August 20, 2021, 02:02:12 PM

I’ll get some up close and personals tonight from my two.

Thank you sir.

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Sammconn · « **Reply #29 on:** August 20, 2021, 03:32:00 PM »

So. I may not be much help.

Spare LBZ pump is out but hose looks similar.

DD has so much crap in the way can’t see hoses.
But. Now that I think of it my hoses have been rebuilt with swage fittings and real hose so as not to leak like the OEM do in the cold.

I seem to recall the guy cuts it on the straight section before the “horseshoe” bend of the OEM.

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JR · « **Reply #30 on:** August 20, 2021, 03:59:19 PM »

Mine needs some cleaning but got 3.