400 DB cat motor starting issues

[Daveatgirouxs]

Anyone have cat 3116 that now and then crank but don't start. It's not our fuel shut uff selenoids. I've been told an injector hanging up and keeping rack from moving. If I play with things long enough it usually fires. Once I reprimed motor then started but don't know if it was a coincidence. I have valve cover gaskets in board just in case but really don't want to just start guessing. Any advice would be great. Only does it 1 out of 10 times randomly.

 

[ImpulseIII]

Intermittent problems are best left to the pros. Have a certified Caterpillar mechanic have a look. You will get 10 different solutions from 10 people here (mine included) and most of them will be wrong.

 

[sb in gp]

Great group here but imho you should also ask over at boatdiesel.com.

 

[fwebster]

What you have sounds like a fuel starvation problem. That can be either a lack of fuel or an air leak allowing air to get into the fuel valley. How have you verified that the fuel supply solenoid is good? There is a relay and a solenoid. The fuel supply solenoid is internal to the fuel pump so unless you removed it, I don't know how you verified that it is working.

An air leak could be from the Cat engine mounted filter or the priming pump or any of the plumbing down to the fuel pump. When you "play with things long enough", you are could be either triggering the solenoid enough that it eventually opens or just pumping enough fuel thru the system to force the air out go the fuel gallery and into the return system and the engine fires. You can verify an air leak if you replace a section of the fuel return line with clear tubing to check to see if there are bubbles in the return.


One thing is certain........nothing under the valve cover is owner serviceable unless you have the correct gauge tools for the 3116. If you are satisfied that you do not have air in the system, then call a Cat technician who has the correct tools and training.