Ok as you lot know all I thought I'd bounce this off you.

I've borrowed a 3 ton mini digger but every so often it loses engine power, it may be going off a cylinder. It's a 3 cylinder Diesel Isuzu engine. Now I know nothing about diesel engines but I guess a good start would be dirt in an injector. Whats the best why to check/clean?


J

Fuel filter is a good place to start!

Yep fuel filter sealing ing Drawing air would be my first suspect

Also check to see if any of the rubber inlet pipes are getting sucked flat.

Thanks for the ideas, l'll find the filter and check the hoses in the morning.

J

Almost certainly fuel trouble of some sort, but first off don't go touch the injectors! Most mechanics don't do anything with diesel injectors & little with the injection pumps either, if something is thought to be wrong with them then it gets taken off as a unit & sent to a specialist that has the kit & knowledge to work on them. If the filters have done their job there won't be any dirt affecting them directly.
Have a look over the fuel system in general for evidence of a leak, damp areas on pipes & unions etc, if fuel can get out then air can get in & diesels do not like that.
There may be a pickup filter in the tank so find out if fuel is coming out of the tank, and that is is clean fuel with no water in. Move on up the system checking for blockages & dirt or water in sediment bowls & filters ("banjo" type pipe unions are great for trapping dirt & blocking up).
Has it got a lift pump of some sort? Usually a simple diaphram pump with one-way inlet & outlet valves which can get dirt sticking them open or even the valve can fall out of its seat, or the diaphram could get a pin-hole but that would usually leak fairly obviously. If it's an electric pump they tend to be reliable enough but is it working?
Once the problem is found & corrected you'll need to bleed air out of the system through bleed screws on the filters & pump usually by mechanically operating the lift pump with a lever on it, I've found the lift pump on these little Jap diesels in diggers etc wont pump fuel until it actually has fuel in it, so you may need to help it by lightly pressurizing the tank with an air line.
And I have seen air filters blocked enough to suck the inlet hose flat as Owelly suggests!
Good luck!