john deere 455 disel enging vibrates when only it is running

[lklawson]

455 disel engine with a vibration when engine idles the engine speed will go up and down and viberate when trottle speed is increased it runs at a regular speed but still has viberation issue what can be causes

 

[slow wrench]

You could have air being pulled into your fuel system through a cracked fuel or return line.Air bubbles being pushed through the injectors will make it shake and vibrate.You may see little or no sign of a leak.

 

[KennedyDiesel]

How is the fuel filter?

When you key on do you hear the electric transfer pump run?