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.

Cummins ISC Diesel Engine Fuel In Oil Repair.

The Cummins ISC Diesel Engine is a great performer, we have several in our fleet and they are a very durable diesel engine. As with any engine there are failures and in this case we experienced the oil level increasing to an over full condition. One test that told us it was fuel in the oil was the oil sample analysis. We took a sample and the guys at BTA in Kamloops faxed over a report to let us know it was in fact diesel fuel.

Another tell tale red flag was the oil pressure was dropping below normal along with a splatter of oil on the rear engine compartment door. The viscosity decreased making the oil thinner causing these conditions. We actually went through this repair before and the symptoms were exactly the same (that's what happens when you have a fleet with the same drive train).



The CAPS Fuel Pump has to be replaced to repair this condition since it provides the high pressure fuel and injection delivery. It runs directly off the accessory gear and is about the same size as a 2 cylinder air compressor. The fuel lines and accessories have to be removed along with the pump accessory drive gear. The first thing to do after this repair is change the engine oil and get rid of that thinned out engine oil.

Replacing Worn Alternator Pulley Serpentine Belt

These are typical pulleys that run a serpentine belt on a Leece Neville alternator. The alternator pulley on the right is the original and is worn on the top edges of the pulley grooves. They are flattened out from belt wear which tells you how durable today's serpentine belts can be.

Of course we launced a campaign to replace the pulleys on the other buses spec'd with the same alternator. Click on the picture above for a closer look (if you could hold these pulleys in your hands you would see the wear much clearer)

The alternator puts out 160 amps so there will be a substantial load on the pulleys and the belt. The engine is a Cummins ISC which uses a tensioner pulley. If this pulley was left on any longer there very well could have been belt slippage eventually. Most mechanics (myself included) would not notice this wear especially during an alternator replacement.

We looked a little closer in this case because of a recurring charging system problem. That's what happens when you look a little deeper into a stubborn mechanical problem.