2004 Chevrolet Silvero this is the 66 lb7 Duramax This is the first Duramax truck uh or the first uh GM truck to have the Duramax after GM rotated out of using the 6.2 L and the 6.5 L turbocharged engines in the OBS style. Chevys So this is the cat Ey style that got the first Duramax which is an Isuzu engine. It's V8 It's got a CP3 high pressure fuel pump and8 fuel engine ectors along with a turbine charger. Uh, it is a similar gravity.

it's a similar truck to my Silverado Body style is the same but this one's an ' 04 and early production. Mine is an ' 07 which is late production and uh, they had some changes along the way so we can clearly see that. this particular truck has, uh, it's seen some better days. It looks like it's been parked and laid up for quite some time.

Um, customer States Fuel system issue Now when I got this truck, it came in uh, on a tow truck that had the thing towed here and batteries were stone cold dead on it. They had no power I Tossed in the old batteries that came out of my truck when I upgraded them. So it's got a pair of a decent die hards in this unit right now so that should be enough to crank the thing, start it, see what it'll do. So uh, let's see if she's going to run.

I Did have this thing started earlier. Uh, it took about 45 seconds of cranking to get her to go so we'll see if she's going to start today. beginning engine starting sequence now. Nope.

Gas on it. open up injector pulse. Come on. come on.

you can do it. Run and it's got a lift pump. It's got an air doog lift pump down the frame rail I Don't know if it's coming on, but it's got one. Take two.

Come on you p said Chevrolet This one's not happy I'm cranking cranking cranking. Seriously? she's not going to light off. Wow! I Got it to run yesterday, but looks like today it doesn't want to do it. Let's get this, uh, scanner plugged in.

Maybe it's starting to set some trouble codes. The battery was so dead that it wiped out all the Ecm's memory so it had to no store Dtcs when I got into it the other day trying again. Come on, it's not even thinking about it. Okay popping asy Hood I'm going to figure something else out I Know it drives and runs cuz I parked it here.

we're we're going to need some combustible aerosol. uh. starting fluids. Nothing in there.

Brake clean. Brake clean will totally work. We're going to run this Duramax on Brake Parts Cleaner. Yay darling! Will you help me out? I Sure will All right come over here this way I Want you to hop in this uh piece of Chevy right here and you're going to crank it to try to start it.

When you go to do that, you're just going to hold the key down. Just keep going and going and going and going. Um, while it's cranking, put your foot to the floor. okay on the yeah on the accelerator pedal.

Yep. and once it starts to start, let off of that pedal. Okay, so try it right now. Yep, so crank it, hold it put to the floor.

Okay, stop for a second. Batteries are getting low already I can hear them. We're going to try to get her to light off with some uh, some uh brake clean here. Open up all right, darling.

Go ahead and send it. There She Goes do one more for fun. see what it does. See how the RPM is coming up when I Give it some spray.

Okay, well. it's running now. This is good. stinky brake clean.

Being burnt through a diesel does not smell good. Here you go, Sweetness. Will you take that inside for me? Will I Will take the vehicle from here I'm not going to drive it cuz it'll probably leave me stranded. but it's running now now.

Full disclosure: This vehicle was at another shop once upon a time and it was towed out of the other shop. Uh, I Believe they told him he had a massive fuel system problem and it probably needed some fuel injectors. Uh, now now these vehicles Here They were a a suction only fuel delivery system to the highpressure fuel pump and uh, well. what I'm getting at is they never had a uh, an electric pump to deliver the fuel.

This particular truck has had the fuel filter deleted on it and they've installed uh, what's called an air doog filter system which is a filter and a lift pump and a uh, a water separator which is down here on the frame row. Let me show you that real quick. it's a brand new unit. Yeah, there she is that right there.

That's the lift pump. Okay I don't know if this thing is on or not it's plugged in, but I can't tell if she's running or not. So first thing we're going to do is try to diagnose this thing. It's a brand new assembly.

They just replaced it. Fuel comes in from the tank, gets pumped through the pump, pressurized, and then it's sent to the Uh injector rails up front at the engine. Yeah, let's get out of here real quick. Oh my hat.

Oh no. So what's interesting is that combustion did not begin until I introduced another fuel source and now we can clearly see that it's running on its fuel source. So I hypothesize that these fuel injectors are in fact delivering fuel to the engine. But perhaps they did not have the Uh, the appropriate pressure or the appropriate volume to actually get the thing to light off at first and begin the combustion process.

Uh, hence the uh, the starting after I gave it some spray. So uh, what? we're going to do I'm going to fire up this scanner here and get into our ECM and we're going to take a look at the Uh, the fuel pids, the uh, all the data for the fuel injectors. We're going to check for pressures. we're going to check for uh, flow amounts, and of course, course trouble codes things like that, and we're going to try to determine what's going on with this truck's fuel system.

I Think it's got a lot of things going on. It probably needs a set of injectors if I recall these uh, Lb 7s were horrible on injectors as it were or as it was and they required replacement right around at 100,000 Mi And if we take a look at our odometer on this particular truck, we're looking at oh I don't even know how miles do we have on this piece of uh Chevrolet Here, 160 something? some change? Where'd it go? 163 757 on the odometer. So this thing could be approximately 63.75 s% overdue for uh for its fuel injector replacement. Anyway, we've got a Silverado uh, looks like it's two wheel drive because the switches are not present.

So we're going to do a rear wheel drive that's rare Crew Cab Rear wheeel drive Silver A huh? Okay, anyway we're down here at the 66 V8 turbo diesel Lb7 and no, not the LL Yeah, that's the Lb7 diesel. Okay, uh. pulling her up, we're going to look for codes first and then we're going to pull up data. I Don't think there's going to be any codes in here I Also learned from uh, past history that another dealership or another facility had replaced the cam shaft position sensor and the crank position sensor I Guess they had said that it didn't start because those sensors weren't working.

So basically what we're going to we're going to do is look at all the data, confirm that it does have Cam and crank signal cuz that can cause what we just saw. but uh, I'm thinking no codes yet I'm thinking it's going to have a a fueling issue they always. That's that's what's wrong with it because diesels only. they.

They need air and fuel. That's all they need. Um, okay, so no, no trouble codes. Let's pull up some data here.

Bagging up, bagging up Bing up bagging up data I Want fuel system data Fuel data: Okay, a throttle position that's responding to my foot RPM Fuel Temp Fuel rate in cubed millimet Pilot fuel cubed millimet I Don't know that one. See if we've got injector quantities here. Coolant mass airflow is working. Let's let her down here.

Fuel level: It has fuel in it. We're not moving H I Did not get the data that I was looking for. These are not droids are looking for. Let's try engine data I Wonder if the AC works.

It's getting a little warm in here. Let's fire up the climate control. see what it does. Do we have cold? Nope.

Okay, I'm in engine data 2 We're going to go ahead and scroll down. What I'm looking for is injector rates is what I'm trying to find here. So we've got I think CMD What's CMD Is that like a pulse width? It's in milliseconds I'm assuming that's pulse width. So what we're looking here: Injector 6: 53 milliseconds.

Uh, Injector 1 35 So we've got kind of a spread going on here. We're in the 40s High 40s low 40s balance rates. Here we go. Balance rates in millimet cubed.

Uh. Starting off with one, one's A -3 so cylinder number one is being told to pull away a little bit of fuel Eight? uh, Or8 on number two and number three. those are okay. 04 on number four.

That's okay. Um, see, these are all close to the zero. Mark We've got3 here .1 So that one's pulling away some fuel. this one's adding some fuel.

But look at the spread here. we've got 3 mm Cubed on Cylinder 6 adding fuel and cylinder 1 is taking away fuel. So what this is telling me is these injectors are not spraying evenly. So here I know let's go ahead and shut this thing down.

Watch this. we're all going to jum jump down to zero. We keyed back on. so restarting and it won't restart.

Foot on the floor and it's not even going to restart. That's cute. Going to have to give it more spray. I Guess let's see.

let's see what it does when I crank There She Goes Yep, Foot on the floor, she lights up. You saw how fuel started coming into play right there. Let's try one more time. Right when it wanted to start, we saw the fuel start to come in, cranking foot on the floor.

and if I raise the idle speed, we're Back in Balance Again, let's go down to balance rates. Those are all zeroed out and down at idle. We're back to our crazy numbers here. So the other shop had said that there was air in the fuel system at some point and they told the guy that he needed a new uh lift pump.

So he put in a new lift pump and they're staying. It still has air in it. They were saying it has air in it because the injectors are pulling air into it and injecting that. Uh, the injectors aren't going to bring in any air.

It's not an air situation. What we have is a fuel delivery quantity situation. Uh, there could be some air somehow entering the return lines going back into the tank. I I speculate and some of the some of those uh, those lines are bridged over to other injectors on that cylinder bank so it could be introducing some kind of air.

but I've I've never encountered such things. Um I Didn't spend a lot of time working on these Lb7. These were slightly before my time. uh, regarding my skill level I was in the field back in the day, but when these were popular, I wasn't qualified to work on them.

So I I know the uh, the later modeled units. but I don't know this one very intuitively. In fact, if I determine that we need to put injectors in this, and I end up doing that, this will be the first Lb7 that I have done a set of injectors on. So here's the plan.

We're going to get this thing inside of the shop space. I'm going to bring it inside. Uh, we're going to get it up in the air and can you see where we're going here? I'm going to get it up in the air and we're going to key it on and we're going to check for that lift pump to be actuating. If that lift pump's not coming on, we probably need to fix that first and then, uh, we'll move forward to the injectors later.

Uh, one other thing I Understand that someone has already installed a replacement CP3 pump in this. That's the high pressure fuel pump. That's the one that'll take our zero pressure fuel and crank it up to like 24,000 25,000 PSI That way, the injectors have some fuel that they can work with and that they can atomize. So now that I'm done talking and uh, introducing what we're doing here, let's get this thing spun around in a circular motion here and we'll get her into the building and checked out.

so stay tuned. This is going to be a very good video. Hey Lauren's here. What's up darling? You have a phone call I do? Who is it? So if I was ever going to wreck a car into the door or the wall, this would be the car because of the the cellan paying a bit of business here.

I don't know if I'm going to make it Dave's looking out I think we're good I think Lauren's looking out too. We good, yeah we're good. She's got me I'm already pulled over I can't pull over any farther. just say wait I'll back up there you go.

Thank you teamwork guys. We're watching the corners. We're watching the walls. We're watching the doors of death.

sign language. There we go. Theodus wait, keep bringing me up. I'm going to put myself right I'm going to do the the B pillar right at the lift post as long as she says I can still keep coming up.

Good, nice, nice, nice. Thank you darling. Parking is the AO I Just saw a four right there too. Oh man you coming You were coming in here blind I was totally well I mean I got this I can't see there's there's that I stood on that side the whole time I was staring at her so yeah I was totally blind trying to drive this thing I was guiding you.

That was a compliment you oh you did fantastic You did good see I Have my my bright color gloves too. You got your your aircraft maneuvering gloves y BR Yeah Anyway, like I was saying though, guys, we shouldn't be seeing all this right here. So there's either air in this system or or there's something else going on. let's check the lift pump.

I Think we need to put injectors in this but uh I guess we're going to find out. so let's hop on out of this unit. We'll power this down for now. Please exit current, test whatever, backing up, impatient see if it's going to restart again.

Nope. Yeah, there we go. Okay, skipping ahead so we do not make this 1.5 hours of video. We've got the rack set up Dave Help me out.

Green subscribe button. Let's run this thing up in the air a wee a little bit and pay some attention to that lift pump down below. First, let me check my lift and make sure we're safe. Good good, Everybody's good.

We got to give it the shake down here so we're going to go little bit left and right. That's fine, we're going to go up and down as well. Snap crackle po I Don't know what that was. Probably just rust things breaking off due to rust.

Anyway, we're good here. We're not good here. Something's not right because I used this on that side, but this one is shorter. Need to switch that out.

I've got the wrong wrong bit of business going here. Did that scare you? Oh my gosh that that lock was caught? Uhhuh. Well that's why you check them to see if they're going to fall off while they're down here. Yeah, that way they don't fall off while they're up there.

Ooh that was. oh that was nothing. I have seen some things in my day, sweetheart that but you noticed you realized the danger. See, it all feels nice and safe and simple up until it's not.

Yeah, until it. I I Know that seems like self explanatory and self-evident but uh, folks, don't realize that until that moment of uh oh crap. we're all going to get smashed and die Y. So we got center of gravity here.

Keep in mind this is a diesel so there's a lot of weight right over there. But we've also got this super long box with the one T axle so there's a lot of weight back here too with leverage. So we have approximately found the center of gravity of this truck and look here. Just like my truck, you get some frame flexs cuz of all that frame we've got 1573 in wheelbase on this truck.

That's a lot of inch. Lot of wheelbase inches? Yeah yeah. I can't reach look at that Yeah it was not built for a big handy people. I Defeated the safety mechanism.

Let's set it down on the locks. nice and gentle. Like there we go, we're good. Think no more.

That was fun watch. It's like when you walk and kick yourself in the behind at the same time. Bam Uh yeah. I'm infantile Juvenile and definitely not mature at all times.

I Fake it. rolling, rolling, rolling. I Didn't roll my cart enough down under here blue and take a gander at this lift pump. What we want to determine is if it comes on or not it's going to be a step.

I I Think they installed this air dog pump. Uh, just to uh, what you call it like to try to fix this situation, to try to fix the problem here. I Think that's why this is why this exists I'm not entirely certain, but very much a real possibility. So what we're looking at is looks like that's the power wire clearly positive in a ground.

you got that one dangling, don't know where that goes and then this harness runs forward. So I Want to see where this is connected first. We can just make sure that pump's even powered and it looks like it runs up there somewhere. So we'll have to find that from the the bottom side or the top side rather.

So what we've got. We've got a line coming in from the tank, so that comes in goes through the filters, the pump pumps it, it comes out somewhere and then runs back to the line. That one right there line up top comes to the frame, follows the frame going going, going, going and that runs forward and meet the engine somewhere up there. Okay, so that's all looking good so far.

and the return line is the smaller line. Let's see, it's going to be this one right here which also runs runs along the frame so that one's just going straight back into the fuel cooler which is right here. See, the diesel fuel also serves as a cooler for the injectors. Again, if you're at 20 something th000 PSI you're going to put a lot of heat into that fluid to generate that pressure because pressure and heat, uh, affect each other or they correlate.

Rather so, we have to have a cooler in line somewhere to give some coolant capacity to the fuel before it's returned to the tank. That way you don't start pumping 200 diesel fuel into your tank and then you hit your tank up. H see exhaust Delite Yeah, got a leaker too. Look at that.

There's some soot, right? There's a mosquito that's been biting me in the ankle that hurts ow I'm Noggin Okay, so I'm I'm not seeing anything crazy down here. uh I think what I'd like to do is I'm going to power and ground this just so I can hear if the pump comes on and if it comes on then I know the motor works and then we can determine if it's getting power when the key is turned on. So we're going to probe this with a power and ground source and then kind of move forward from there. So visually, everything is looking, uh, co- pathetic.

Let's go get the jumper packed here and some leads and we'll run. Uh, we'll run some power and ground to that, uh, that pump over there. Now Like I said before, this vehicle was never originally equipped with a lift pump, but it has one now and since that is now part of the fuel system, we have to diagnose that as well. Kind of a.

It's kind of a different animal here, but we can work with it all righty. So I've got a positive lead connected to the uh, the pump assembly which is also connected down here to the jumper pack. The ground wire is connected to the jumper pack and what I'm going to do is we're going to energize this jump box. You'll hear it beep a bunch and we're now sending power and ground down these wires.

So when I touch this to that other pin, this pump should come on. Yes, we are pumping. We can also see that this is the output side because that line flexed. Under Pressure So we're getting some flow here.

I Have an idea I Want to find out if this thing is sucking up air from the tank and pumping air into the system? That's also a possibility. So I think what I'll do is disconnect this pressure side and we're going to hook a hose to it and we're going to run that that hose into a bottle and start pumping. Fuel And we're going to look at that fuel and see if it's full of air bubbles or uh or not. If it's full of air, then, uh, we may have an issue back at the tank and we'll have to start looking in that direction first.

So here let's go ahead and start by disconnecting this pressure hose right here. It's either going to spray everywhere or it's not. but I should this thing should be depressurized? I'll uh, I'll pull it back slightly at first if I can get the clip to uncp, what is it? Oh, come on, you. make sure you didn't want to save this it.

say half of a oh, the half of a saw blade? no no, that one. that one broke. you like to I Don't save half half saw blades though. that's I mean I might be a pack RP but that's a little too far so this stupid thing's not unclipping.

Tell you what. Let's get smart. I'll just take the uh, the hose clamp off. Doing this the hard way Okie does Let us disconnect this little uh, this hose clamp here.

Pull the hose off right here or not. No. I'm not that's not even close to wan to come out of there. I can't get this apart.

Please come off heart please please please please please. that's in there too. Oh, hang on I think I got got something going here. the uh oh I see what's happening? I'm silly look look look look look look look.

this fitting is hanging up on the other fitting. That's the. that's my problem here. See that we got a clearance issue and I'm dripping fuel on my jump box.

Look at that fire hazard. That's not cool. Pigat, That's what I need Come here. put a towel down there.

Well now I Realize the arrow of my ways. see if I can't sneak this thing out of here without taking the other line off. There We go. there, we go.

Now we're getting somewhere. So I've got a piece of Hose Here it's clear. oh that's perfect. Look at that fit right over.

How about that? This is actually the the hose for my uh, my 8090 gear oil. It's reallying the 5 gallon tub anyway. What I shall do is we're going to take this hose, stick it into our tank there and now I can supply some power to that pump. So I've already pre pre-wired it I've got the yellow which is the hot side and then the green one is the ground side.

So what I would do is just connect the two grounds. and when we hit the switch on the jumper box that will uh, that will fire up the Pumped So I'm going to reach down, hit the switch. We're going to watch this fuel and we're just going to see if there's a bunch of air pumping through this fuel line or not begin fuel pumping now. Okay I don't see air coming through, that's it's.

pretty clean. Let's take a look at what's coming out and we can check the volume as well. Fuel looks good, there's plenty of it. Okay, shut this down.

Well I Don't think we have a tank problem I Don't think we have a uh a lift pump problem. We've got an injector problem. Let's go check real quick and verify that the CP3 pump and this engine was in fact replaced and uh, if I find it it's been replaced in that all the stories check out. I'm going to have to recommend the uh set of fuel injectors on this truck.

I Also like this lift pump I think I want one? let's tighten this clamp down real quick. Like here. Put that back where it goes. There we go.

Yeah, what these are supposed to be for is to eliminate the burden that the CP3 pump has while trying to draw its own fuel supply. Uh cuz they don't come with a pump so it just requires on uh fluid displacement as the as the CP3 up front on the engine pumps fuel into the injector rails that fuel comes from before the pump and so when it pumps it out, it creates a lower pressure in the line and it just naturally sucks its own fuel from the tank. This thing is designed to actually give it some pressure from the tank. that way it doesn't have to work to suction the fuel so it makes the uh, the fueling system much much more efficient.

Okay. Flashlight Recovery jumper boxes off. let's get out from under here, park all our stuff off to the side where it goes. Stay there flashlight.

That one goes like right there. So let's let this thing down. take a look under the hood I Want to put some eyes on that pump assembly? the CP3 pump. that's the high pressure so we've got low pressure pressure lift pump 7 to what? 20 psi maybe? I don't I don't really know what the pressure is and then you've got the high pressure injection pump 25,000 PSI up to 25 moving on up, locking release down button slowly slowly coming down see how it went sideways.

That was fun and then once we're even and settled we can let her ride picking up heavy. Vehicles not for f of heart oh my God don't go over there I was saving I'm saving your communication device you saved my telecom Communicator So here let's reach on in through the through the security glass. here. there's that uh lever popping in.

Z Hood Woo There we go. Okay, so our CP3 it's buried down there. it should be underneath of this pipe and right here under all that. I don't know if I could even see that unit in there.

Okay, let's get some more light going back in. Hm, What to climb on a ladder? I'll use a ladder There we go there, we go. ladder in place. let's climb on up here.

So we've got our turbocharger back here into the heat shield that's the down pipe intake pipe charge, air pressure side or no, that's the cold side cuz compressor pumps the compressed air that way through the hot side pipe down to the intercooler which is the uh, the air radiator and then after it leaves, the intercooler comes back through the cold side pipe and down into the intake manifold. that's the air induction system now down here I don't see well I can see pieces of the CP3 I can see the back of it. Uh, if it's been replaced, it's not that new. Yeah.

I can't really can't really see what I'm trying to see in there. Yeah, there's just too much stuff in the way, but it's back there. um well, the pump wouldn't be the problem cuz if the pump was a problem, it would have uh, turned itself into glitter and then sent all that Glitter down into the fuel injectors. thus running the injectors.

And look here. this is the pain in the butt version. See how? we've got our fuel lines right here. Coming in, the injectors are under this valve cover right here.

So in order to get these guys out, we've got to strip all of this off the top of the engine ecus. have to go away. piping has to go away. uh, hoses, you name it.

alternator has to go away, the crossover or the uh, the Y bridge rather has to go away. I Think the turbo stays there, but AC compressor's got to come off. Then we can get these valve covers off once the valve covers are off. Then we can get to the injectors and attempt to extract those guys.

So yeah, it's it's a big job. Uh, if memory serves, I think we're at like 14 hours of labor to replace the entire set of injectors. Uh no, I will not just change one or two abolutely not. These are going to have to get done in a set or I will not be able to do the job because it's just uh, that's not very realistic.

Yeah, doing one knowing another one is Nan seconds away from failing is a recipe for a disaster. and I I'd rather not do that. So what I've got to do here is I'm going to go ahead and uh, build the estimate to replace all eight of these fuel injectors. Uh, we have to replace the uh the injector lines that go with it.

Those are onetime use and of course we'll have to do uh rocker. SL valve cover gaskets as well. So it's it's. actually a very huge, ginormous type of job.

Very labor intensive. There's a lot of stuff going on and diesel fuel injectors are not cheap. Look them up, you will see. So I I Have no more disassembly Today We're going to put a set of injectors in it using process of elimination.

I've confirmed what others have told us before about this truck or what they've told the owner, the dealership rather. Oh, look at here we can see they've recently done a fuel pressure test on it. The cap is gone. Yeah.

Okay, so based on all that guys, we need to either uh, put injectors in it or not at all. There is no Band-Aid to fix this. It needs what it needs and uh, and that's just the way it is. So I've got to build this estimate, call a guy up, see if we can, uh, if we're going to do the job or not and then kind of go from there.

So having said all that guys, it's Friday it's 5:00 holiday weekend is coming up I'm going home not doing this job today. Not doing this job tomorrow either. Uh, or on Sunday for that matter. So maybe we'll swing back around to this uh next week.

but you can see Dave's locking us up. That's my queue. We're going home. I'm going to close this video out right now and I will do such as always by thanking each and every one of you guys for watching this video.

Certainly hope you enjoyed this Diag video. If you did enjoy this video, please feel free to let me know about that in the comment section down below. Do not forget to tap that like And subscribe button while you're down there and most importantly, have yourselves a fantastic day! See you guys later in a video in a Chevrolet in Lb7 Duramax and a fuel system injector problem for now.