Sunday, January 09, 2011

No Start Cummins Diesel Engine

Cummins Diesel Engine
Here are a few tips and checks you can make when your Cummins Diesel Engine will not start. This information pertains to mechanical injection diesel engines.

Don't feel insulted with some of these checks because the simplest steps have been overlooked many times.

The rule of thumb is Check The Simple Things First!

  1. When your Diesel engine cranks but will not start - No smoke from exhaust
  2. Is there fuel in the supply tank? Always check the source on your diesel engine
  3. Check electric or manual fuel shut-off.
  4. Is the air intake or exhaust plugged?
  5. Note: Remember, a diesel engine needs air and fuel to run
  6. Fuel filter plugged / seperator full of water?-drain as required.
  7. Your diesel engine injection pump not getting fuel or fuel is aerated. Check fuel flow or bleed fuel system.
  8. Check inlet restriction to fuel transfer pump
  9. Inspect lift pump operation. Remove outlet line and crank over engine
  10. Worn or malfunctioning injection pump
  11. Internal pump timing incorrect
  12. Engine camshaft out of time
My experience with diesel engines has taught me to start from the source and work my way to the injectors.

Check the filters to see if they are still full of fuel, if not you've got a diesel engine that has run out of fuel - a no brainer. I went on a service call once and found out that the operator had filled the tank with gasoline, anything can happen!

Otherwise you have an obvious failure that you have to sink your teeth into. Replace fuel filters if the mileage or hours are excessive.

Check fuel lines from the tank to the primary filter [Fuel/Water Seperator]
Tip: I use a remote fuel container and slip the suction line before or after the primary filter. If diesel engine performance improves you know you have to start checking for faults back to the tank.

This procedure bypasses the fuel tank and lines up to that point which tells you if the problem exists in those areas i.e. restriction or split/cracked fuel line or bad pick-up tube in the tank.

Pull output line off of the lift pump on the side of the block and crank engine over and check for fuel output.

Prime fuel system with primer pump and bleed the injection pump, once primed crack injection lines at the injection pump and observe for fuel output.

In most cases you will find a problem up to this point, if not check injection pump timing or check to see if the camshaft gear is actually driving the injection pump. These failures are not common at all.

I hope these tips help you troubleshoot your Cummins Diesel Engine.


chandra said...

Many don't take this serious but when Cummins Diesel Engine problem occurs its always difficult..i appreciate your helpful tips..

Maintenance Job Description

little said...

I have a 1991 Thomas Built School Bus, a Saf-T-Liner, with a Cummins 12 valve turbocharged inter-cooled 5.9. This is a rear engine model and has the air fuel pedal, treadle, assembly. The transmission is an Allison AT545. The motor runs great and the tranny shifts up and down strong. The problem is that sometimes the motor ,when in any gear either pulling a hill or going down a hill or just taking off, will just drop off and idle. The pedal does not fall and the pump stays fully throttled or in the "wide open position" while the motor surges. I have changed all filters and ensured there is no leak in the Air Treadle system, I did find a leaking tranny modulator which was replaced, and a faulty actuator, which I removed and replumbed to exclude the actuator as I was told the 5.9 doesn't need a fast idle option. The problem is intermittent and happens when the motor is hot and cold, there doesn't seem to be a common denominator as to when this happens. Any help would be greatly appreciated.

Ken D said...

This is a question not a comment.Afriend of mine had this problem with a diesel Mercedes engine in a Sangyong???
The engine would not turn off and he didn't know how to shut it down.In your opinion what is the safest way to shut down a diesel engine without doing harm or the least amount of harm?Turning the key off didn't shut down the engine and it wound up overheating and engine damage as you can guess.


J. E. Whelan said...

Little, I would look into the Bosch injection pump and get it tested. In my location I have a really great injection shop I rely on for this type of problem. At least I can ask them for help and advice.

J. E. Whelan said...

Ken, The best method is to cut off the air supply to the air intake system but you need something really tough like a 3/4 piece of plywood over the air cleaner ducting. Cutting off the fuel takes much longer but is another option.

Soheel Ali said...

just stall it on fifth gear!

Auto body said...

Those tips can really come handy at the time of need.