Cummins injectors…

Noel

Noel

Well-Known Member
Joined
Jan 20, 2010
Location
Sophia NC
I have a 2006 common rail 5.9, started to notice a bit more hazing black smoke and then came the trashed fuel mileage. Have read that the lift pump could cause bad mileage but not as much the extra smoke. That being said I haven’t started to diag it deep and check the lift pump for volume. As I know it’s probably gonna be an injector…. Everyone says to replace all at niece kinda thing, but I’m not interested in throwing 6 injectors if I can find the culprit. I had a prior starting issue with an injector I was able to pinpoint by blocking them off one by one with a cap til it started, which gave me my faulty injector. This issue is a bit different, as I could haul my camper to the beach and back on a tank of fuel. Last trip took 3/4 each way. My thinking and I was asking for you alls opinions. If I were to get a thermal imager and watch the exhaust manifold, I’m hoping to see a runner maybe 2 with a big difference. Does this seem logical? The few diesel folks I have talked to all day all 6 yet can’t really recommend any brand as they are all having quality problems… I’d rather buy one injector and worry than 6
 
I have used a thermal imager for this but depending on the exhaust manifold style its pretty inconclusive . I usually just take a rag and a wrench and crack a line at a time while it's running and listen for change. You can do some real damage to a diesel engine with a leaky injector, you can also beat the crank up with a mismatched set. I'd suggest changing all 6. I guess you've confirmed turbo still building boost and air filter is good?
 
braxton357 said:
I have used a thermal imager for this but depending on the exhaust manifold style its pretty inconclusive . I usually just take a rag and a wrench and crack a line at a time while it's running and listen for change. You can do some real damage to a diesel engine with a leaky injector, you can also beat the crank up with a mismatched set. I'd suggest changing all 6. I guess you've confirmed turbo still building boost and air filter is good?
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New filters and boost guage showing normal. I do plan to do a actual pressure test on the system and confirm
 
Replace all 6…
 
Noel said:
Yea, I would have agreed a few years back. But I have a couple buddies who have recently and are both dealing with bad injectors. So makes me wonder why do all 6 if I can prove my fault?
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If you can afford your truck being down have your 6 rebuilt
 
Ron said:
If you can afford your truck being down have your 6 rebuilt
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That’s a thought I have had as well. The local injector shop is proud of their testing, so I think they want to rebuild them. I don’t need my truck that much as I have a couple other vehicles I can tow with. Just my camper requires the truck.
 
I have had a set from F1 or Flux diesel in my 05 for 8-9 years. Recently started having some long start issues and shitty fuel mileage. Pulled them last night, they are headed to TX in the morning. Called and spoke to them about a testing and cleaning and they informed me that the service is free since they are their injectors. Thought that was pretty good. When I bought that set, them and exergy were supposed to be the best in country.


Also how's rail pressure look?
 
Junkyard Dog said:
I have had a set from F1 or Flux diesel in my 05 for 8-9 years. Recently started having some long start issues and shitty fuel mileage. Pulled them last night, they are headed to TX in the morning. Called and spoke to them about a testing and cleaning and they informed me that the service is free since they are their injectors. Thought that was pretty good. When I bought that set, them and exergy were supposed to be the best in country.


Also how's rail pressure look?
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Great to know!
 
Noel said:
Yes! Lol 😂 it does have 313k with not much history known…. I know… if you don’t know do all 6
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Yea replace them lol ... When mine hit about 180k i had some long start issues. Where one was leaking down and it had to build up pressure before it would try and fire. I ran it down to damn near empty, pulled up to the pump left it running and added CRC diesel therpy. When you heard the engine change tone from that i shut it off and filled the tank. Then ran the piss out of it. Sold the truck at 230k and never had another issue .
 
83oldyoda4x4 said:
Yea replace them lol ... When mine hit about 180k i had some long start issues. Where one was leaking down and it had to build up pressure before it would try and fire. I ran it down to damn near empty, pulled up to the pump left it running and added CRC diesel therpy. When you heard the engine change tone from that i shut it off and filled the tank. Then ran the piss out of it. Sold the truck at 230k and never had another issue .
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Sounds like another issue of couldn’t diag the problem
 
Before you blame injectors, you really need to check the rail pressure with a scanner. It should be able to show you actual vs desired rail pressure. Low rail will make it smoke because the fuel isn't atomizing like it should.

My LB7 would command 23k psi at WOT and could only make 7k psi. CP3s don't last forever. Mine went at 253k, but I see that you're over 300k.

Generally, a leaky/hung open injector will wash fuel past the rings and dilute the oil. Check it and smell for fuel. A hung open injector will usually make it white smoke too. Unburnt fuel from lack of temperature. As an LB7 owner, I know allll about that 😂 It's also absolutely worth it to go ahead and upgrade to a SAC style injector nozzle. They last much, much longer than a VCO nozzle and aren't plagued with leaking issues.

@Junkyard Dog Flux and S&S are the best you can get! Exergy has gone downhill since their original fuel systems engineer left, but they're still not a bad product. Flux really impressed me when Chris Patterson made 3401 hp and 4000+ tq on fuel only with some 350% over hybrids AND posted a video of cranking it at 40 degrees in Utah with no haze at idle. A lot of that is the sweet, sweet Starlite tuning, but it's still very impressive!
 
FWIW, my dads 06 has started showing some signs of injector issues, but it currently has 421k. He bought the truck with 40k on it and as far as we know they have never been touched. He used to average 50-60k miles a year. Doesn't anymore, truck sits some and now things like this have been popping up. They will go to FDI when I can get time to pull them. I said all that to say this. Sitting is hard on this style injection system everyone says thats in the buisness. I think this proves it.

On a side note, the trans has the same mileage. It's coming out fairly soon too.
 
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Just to follow up, that's what I meant with SAC vs VCO. LB7s and all 5.9 Cummins motors used the VCO nozzles and they're very susceptible to leaking with the slightest amount of pintle wear, trash in the fuel, or water intrusion. If they're a 6 hole nozzle, then the pintle has to seal ALL 6 holes and a seat around the inside of the nozzle, or they'll leak. As you can see, the SAC style just seals up the shoulder. Much more better!

FWIW, every Duramax after the LB7 uses a SAC nozzle and Cummins started using them when they introduced the 6.7. If an OEM starts using them, there's a reason!
 
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