Installed a set of BMS 50HP injectors. Brand new. Torqued to specs following manual with new fuel tubes. Adjusted valves only one was out of spec just a little loose.
Started it and idled great with no turbo and valve train open to air. It was the quietest I have ever heard this motor. Really excited. Then I buttoned it all up and finished my pacbrake install and tested it to see if it was building pressure. It was good.
Then i started the cummins again and still nice and quiet, brought it up off idle, great, brought it up to 2000 rpm and it dropped down to idle smoothly. Brought it up again and all the sudden it went to knocking. See video below. Did I stick an injector, bad one from vendor, who is a trusted vendor here so not posting name until I talk to them. Or something worse? Rod?
I have a fuel rail cap coming and will see if I can determine which cylinder is smoking so bad. Still no signs of blow by so I am hoping nothing hurt.
Mine did that after i installed my injectors. I don't know if there was the smoke since it was dark out, but i think it was a fuel knock. I cycled the key a number of times as well as bumped the starter a number of times. After that my knock went away.
No, that percentage is duty cycle on the solenoid. The ECU has maxed the duty cycle trying to balance that cylinder with the rest. The knock and smoke is from the massive amount of fuel it is dumping at the wrong time in the event. Either the injector is hanging internally or something wrong with the nozzle or it is WAY out of balance.
I have no experience with this problem personally but have read tons of threads on it. I have read multiple cases of people having a knock and smoke and it was a bad injector that was causing it. I would loosen everything and then retorque. If problem is still there I would NOT start it again until diagnosing with the rail cap.
Sounds much better. Does disconnecting the wires have the same effect as the rail cap? Seems like there would still be fuel pressure on injector and if it's leaking would still be spraying some fuel. I would personally send all 6 back to be tested. Sucks but it's really the only sure way to know. Expensive engine.
Pull the exhaust manifold away from the head, just a little. Start engine and it will be apparent which injector is stuck. Remove that injector and reinstall, if that doesn't work the injector was bad from the box. That happens sometimes.
At this point pretty sure #6 is the issue. Will know for sure once I cap it off. Vendor will surely warranty it. Will post up who vendor is once it is solved or if they give me any issues.
Old injectors were getting a bit smokey. When I bought it they had replaced just one and they were pretty noisy. Would guess the 5 were original. Was looking for peice of mind with new sticks on a otherwise very sound motor.
Killing a strong cylinder can slow the knock, but the only way to truly know is to cap one at a time on a hung open injector. The only way to get an injector knock is a hung open injector. The vendor should warranty it as long as you used new tubes and or you did not get trash in it. Hung injectors happen and when I installed mine I got a knock ten minutes after startup that went away after a key cycle. Guess what it hung open months later 230 miles from the house. So for you guys that got it on start up it may not be over just yet! Thought I would throw that out there.
Yep new tubes from same vendor. Kept everything clean. Used vasiline to lube the O rings. Each injector clicked in and so did the tubes. Used fsm procedure and torque specs.
Have good filtration. Air dog 2 followed by the factory filter with a Baldwin element in it.
Another trick for helping diagose these issues is to use a mechanics stethoscope. You can put it on the individual injectors to listen to them. This may help if one sounds a lot different. Keep in mind though that this can be a bit misleading at times because you may here some gear back lash from the high pressure pump gears through the injectors or lines depending on how the gears are lining up with the engine power pulses. Also some scan tools allow you to turn off individual injectors with the motor running. It's just quicker and easier than disconnecting the individual wires. Using the cap is still best IMO. Good luck.
Well got my block off cap today and it was not number 6. As @cerberusiam mentioned it must have been working harder to try and balance out the rest of the cylinders. After 4 more fuel line removals and block offs I found that number 4 was the bad stick. Capped it and all the smoke went away except for a very fine haze, expected with the 50hp injectors and the knock totally disappeared.
New stick should be here tomorrow, I paid for it but will get my money back when they get the bad one back, that way I did not have to wait for shipping and test times.
Glad you found your issue. I've been lucky with my injectors so far but at 200,000 miles I feel I should buy one of those caps to have on hand for when an issue does pop up. Where did you order yours from?
The injectors were from DAP here on the forum. Customer service is great their shipping department not so great but tolerable. I called them and they said I could pay for a new stick and they would refund it as soon as I sent the bad one back in. Not wanting to be down for over a week I went that route. After a few shipping hiccups I got the injector on Thursday and proceeded to break an injector bolt, stupid me looked at wrong torque and popped it. Fortunately it was above the head and came right out with just my fingers. Wife picked up replacement bolts and spare crush washers at Atlantic Cumming for me and I got it installed late Friday finally.
It purrs like a kitten. All my injector rattle is gone from the past 320k miles and the knock is gone. No smoke when idling. Took it for a test spins feels nice and responsive.
Yesterday put about 200 miles on it going to Uwharrie and it ran great. It used to surge badly and buck going downhill with cruise and sometimes even without cruise. Now it just runs along and keeps the speed dead on where it is set at.
Overall I give DAP an A- for their service, would be an A+ if their shipping department had not messed up shipping times twice.
Definitely will buy from them again.
As far as the debate over new injectors, these looked and seemed to match the criteria for being new, barcode on the solenoid, serial number engraved on the tip, rest of the markings on the body looked like BMS, also they were the new shiny coating. 5 of my old injectors were the old style phosphate and one was the new shiny coating when I pulled the old one.
Again definitely would do business with DAP. Hopefully I get the bad injector and cores out on Monday and they get me my core charges and refund processed fast.
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Related Threads
?
?
?
?
?
Cummins Diesel Forum
8.8M posts
379.2K members
Since 2005
A forum community dedicated to all things Cummins Diesel! Originally founded for owners and enthusiasts of Cummins powered Dodge pickups, the Cummins Forum has expanded to include ALL Cummins Engine applications! Come join the discussion about reviews, drivetrain swaps, turbos, modifications, classifieds, builds, troubleshooting, maintenance, and more!