D4 engine (fuel?) issues

[David2452]

V.P. D4 225 at 780 hours
Coming over the Swin Spitway yesterday at a nice steady 17kts and the engine monitoring alarm started shrieking like a banshee and he revs dropped and started surging, not like a constant limp home low rev mode but surging, reduced revs and this allowed a smooth engine at 2k rpm the EVC panel reported fuel delivery issue which was very helpful. After a while trying to increase the revs which resulted in the same surging we resigned to continue at low revs, after about an hour or so we gradually increased a couple of hundred revs at a time and finally achieved a normal cruising speed with occasional bursts to full revs without further issues. Back on our berth the engine warning light remained on after turning off the ignition but after turning the engine and battery off was extinguished and did not come on again. All other instrumentation, Oil, Temperatures (oil & coolant) turbo boost etc remained within the usual during the entire time and there were no unusual noises or smells and no fuel leaks. The fuel filters have done 70 hours since change, no nastiness present in the primary filter drain. I propose to change the filters, (service now due on elapsed time if not hours anyway) fuel tube from the tank all the way to the final engine filter and then test, probably also get Volspec to come and do a Voida analysis, any other suggestions or experiences welcome.

 

[spannerman]

It could be an air leak causing fluctuation in fuel delivery, have you tried pumping the black button on top of the engine fuel filter while the engine is running, this should be firm after a couple of pumps, if not then air is getting in somewhere. As you said go through the system from pickup pipe on the tank to engine filter. If this doesn't reveal anything then you will need a Vodia readout to see what is happening in the fuel system either a pressure sensor on the fuel rail or high pressure pump Mprop valve could be playing up.

 

[David2452]

It could be an air leak causing fluctuation in fuel delivery, have you tried pumping the black button on top of the engine fuel filter while the engine is running, this should be firm after a couple of pumps, if not then air is getting in somewhere. As you said go through the system from pickup pipe on the tank to engine filter. If this doesn't reveal anything then you will need a Vodia readout to see what is happening in the fuel system either a pressure sensor on the fuel rail or high pressure pump Mprop valve could be playing up.

Thanks for that, I will do the simple bit first and call in a proper man if that doesn't produce results.