8.3 Cummins engine has a miss and blows smoke rings--video

[gem1410]

Have an 8.3 cummins with a miss in the third cylinder--no blow by--seems like the injector nozzle may be bad--any ideas on cleaning it up--How difficult is it to remove and replace--video of smoke rings below--thanks George https://youtu.be/wkjD9Mr1GrA https://youtu.be/7Ka0mmHrK_c

 

[JohnnyBM931A2]

Man... That's terrible, but at the same time it's pretty cool looking. Hopefully someone chimes in with a solution!

 

[74M35A2]

You can pull the injector, disassemble the nozzle, and clean it in an ultrasonic tank. That may not be it though. Could be more likely the injector is leaking at the pintle. But even that could be re-lapped in with lapping compound. Easiest would be just to buy a used injector from somebody here so it matches the flow of the others, and swap it out, if you are fairly confident it is #3.

Does the smoke stop if you crack the #3 line open while idling? The 8.3 injectors can be stuck in their ports, and it require a slide hammer to remove them. Start soaking the base with WD-40 or your favorite mechanic-in-a-can.

 

[gem1410]

If there is no wind the whole area is full of rings--I should rent out the truck for kids parties

 

[gem1410]

When I crack the #3 line the rpm does not drop as with the other 5 lines---did not look for the rings at that time--is the injector difficult to remove--thanks

 

[74M35A2]

From a diagram perspective, no, it is just the line and a single bolt retaining clamp. The difficult part will be physically pulling the injector, it corrodes into the head pocket. Some here have made tools to do so and they worked ok. Search the threads, you'll find it. Start soaking it with penetrant spray a few days before, your life will be easier.

 

[CMR2095us1]

Fuel smoke while running looking to adjust injectors and valves

Gem1410 my 8.3 Cummings is doing the same but with hard starts. White diesel smokes pours out the exhaust while cranking. Once started it smokes when cold and hot. Its definitely fuel and not oil or coolant. Was wondering if adjusting the injectors and valves will help but not sure where to get started. Haven't thought about cracking open each line to see if smoke slows down. Also looking to buy pcb box if someone has one.
thanks cmr2095us1

 

[74M35A2]

This issue could also be caused by a faulty OFV (Over Flow Valve) in the injector pump. It is located on the return line fitting at the front of the pump, and controls fuel delivery pressure to the pump. This is a common failure component, but luckily low cost and simple to replace.

An unofficial field test method is to pinch the return line shut with Vice Grips for 30 seconds then release it, with the engine tunning. This allows pressure to build up and flush it when released.

A few people here that have simply replaced theirs have said it cured their hard starts and smoking.

On injector removal, I would loosen the clamp then crank the engine, hoping the compression to help blow the injector off its seat.

 

[gem1410]

I think it was an injector leaking--stuck open --if you drive it 10 miles it should clear up for 5 minutes--you may have to replace the bad injector

 

[mhb285]

Call your self "Mr. Bubble".....

If there is no wind the whole area is full of rings--I should rent out the truck for kids parties

 

[CMR2095us1]

Thanks 74m35a2. I pulled return check flow valve and cleaned today. Unfortunately it did not help but will order new adjustable one to make sure. Is there somewhere I can download TM on injector and valve adjustment. I'm more familiar with gas engines than diesels. My dad was a diesel mechanic but unfortunately he passed away so I don't have my expert to ask technical questions to anymore. My truck is a 1990 M931a2. So far I have put 2 new batteries, changed all fluids and filters and install all new fuel lines. Is there any good place to add a fuel pressure gauge between mechanical pump and IP.

 

[Bandit02]

Take the line off, the clamp that holds it down and crank it. It'll pop out and like rocket. Or a heel bar works too.

The needle in the injector is probably worn out and causing that, Looks like unburnt fuel.

 

[snowtrac nome]

napa cummins and snap on all sell tools to pull the injectors they are essentially small slide hammers the cummins one is the coolest its on a cable and works well around turbochargers, last one I bought from cummins back in 2000 was only 50 bucks back than in my mind it was money well spent.

 

[jess m919]

I just bought the nut for the inj line from a pump shop for $3.00 the welded a fine thread nut to it that screws on my slide hammer pulled them all out with ease the engine was a1995 with 15,000 hrs and never touched

 

[WillWagner]

Thanks 74m35a2. I pulled return check flow valve and cleaned today. Unfortunately it did not help but will order new adjustable one to make sure. Is there somewhere I can download TM on injector and valve adjustment. I'm more familiar with gas engines than diesels. My dad was a diesel mechanic but unfortunately he passed away so I don't have my expert to ask technical questions to anymore. My truck is a 1990 M931a2. So far I have put 2 new batteries, changed all fluids and filters and install all new fuel lines. Is there any good place to add a fuel pressure gauge between mechanical pump and IP.

Injectors do not get adjusted. You can drill and tap the fitting going into the fuel pump and take your fuel pressure reading from there.