Diesel generator cranks but won’t start

Diesel generator cranks but won’t start.
Try again and it still cranks strongly but won’t start.

Check the following:-

  • Is the engine warm to the touch? If the answer is YES , then the block heater is working.
  • Is the exhaust not blocked? If NO blockage, then this is fine
  • Air filters not blocked with dirt or debris? If they are clean then it’s NOT the air filters.
  • Do you have fuel in the tank?If YES, and the Diesel Generator cranks but won’t start? Then the most likely issue is lack of fuel to the engine.
  • Is the fuel line cracked, constrained, bent or ruptured?
  • Check Fuel pump is pumping fuel through the generator?
  • Engine oil in the engine?
  • Any coolant in the engine?
  • Check the batteries – are the connections corroded, flat or even connected
  • Is there water inside the lead acid batteries?

Most Obvious easy fix-

  1. Lack of fuel is the most likely cause because some air is in the fuel line. This causes the fuel to drop back and not enter the engine.
    Our video clip shows how to bleed the fuel in a modern diesel generator.
    If your generator doesn’t have this feature ,then bleeding the fuel to the diesel engine by turning the primary bleed screw.
    Check your generator manual for its location. Then gently turn the screw to allow the air to escape and then re-tighten once fuel begins to appear at the screw.
  2. Blocked fuel filters- lack of servicing and not renewing the fuel filters over time will cause them to become inefficient and finally block with dirt. Replace the fuel filters.
  3. Fuel pump failure- It can happen but it’s rare.
  4. If all the above have been checked out, and operational, then the last resort will be a faulty solenoid. A faulty solenoid,won’t allow the injection pump to push fuel through the lines to the injectors.
    Replace the solenoid.

Mostly likely fix

Of the 4 possibilities we have listed here, the most frequent fix , 9 out of 10 times, is to simply bleed the fuel pump.
If you’re uncertain of any of these points call your local dealer first before proceeding and ask a generator engineer to come to site

Check out our ‘how to bleed a fuel pump’ video below:-

‘Not-So-Obvious’ issues

Silencer – Has the silencer got holes and not been maintained?

It can be also full of water or even the home to birds, blocking the air flow to smoother the generator not allowed it to start. Check for holes. Then use a flexi camera to check inside. If you find water or home to birds etc. then better to replace the silencer than fix it.

Check diesel generator silencer for holes

Fuel – Generator has stood for many years and never been used?

Then your fuel can be like treacle & unusable.

Thick and contaminated red diesel won’t flow through the pipes fast enough to supply the Diesel Generator causing it to starve and crank .

You have two options:

  1. Polish the red diesel fuel in the fuel tank
  2. Flush out the fuel, clean the fuel lines and replace with NEW clean diesel from a reputable supplier.

Fuel hoses can have perished and stuck together preventing fuel flow.

Metal fuel pipes can be bent or nipped to stop fuel flow- check all metal pipes for hidden damage. Replace ALL Filters with Brand NEW Branded Filters.

Never use pre-used or ‘Copy, look alike’ filters. These are cheap for a reason

BUND Alarm

If you have fluids within the bund, the bund alarms and the Diesel Generator won’t start in the first place or it runs a little then will shut the generator down.

Check that there are NO fluids around the generator floor or leaks within the bunded generator

Also check the associated Bunded fuel tank that feeds the generator with fuel

In either case a bund with fluids will NEVER allow the diesel generator to start instead it will crank then shut down..

Solution- clean the fluids out of the bunded area in the generator and also clean up the bund of the fuel tank. Once cleaned then re-start the generator

Container Generators – With Motorised louvres

Containerised Diesel Generator won’t start? Check the louvres rusted closed & can’t open.

If the louvres can’t open then the generator can’t vent, hence won’t start. Firstly lubricate all the moving parts of the louvres. Then check also that the electric motor that powers the louvres is operational.

Test the louvres can now open free and easily. Now re-start the generator.

Closed Louvers Diesel Generator won't start

Finally check all hose connections

The Diesel Generator will crank and not start if it’s starved of fluid to the engine block. – See Photo below

Diesel Generator cranks - Check Hose connections

After all of the above your generator should be ready to Start. If you still have an issue then time it’s to call the local dealer – You’ve done your best.

In reality, a generator will only have issues with starting if it has not been regularly serviced according to the manufactures specifications or the weather conditions have been ignored to the detriment of the generator.

For further assistance, contact Power Continuity 0845 055 8455

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