My lister engine is running pefectly but sometimes.......?

Question

My lister runs well but sometimes maybe once a day it makes a strange knocking like noise then loses revs and chucks out a bit of black smoke then she goes back to normal again. Could it be a bit of dirt in the fuel tank or something like that? she is an air cooled 3 pot and is on my 21 ft commercial fishing vessel. ps she is not getting too hot and as i say she usually runs fine. Any ideas folks??

Answer 1

you got a fuel system problem,, first  drain your fuel tank and collect a sample,, put on a glass container and wait to settle,,if water and and dirt are present,, drain the whole tank and flush to clean,,second replace your fuel filters,,also make sure that all the fuel lines are tight on joints, replace the copper / aluminum gaskets on every connectors..check for broken pipings or bents,,

if you are using rubber hoses, make sure that the inner wall was not damaged.sometimes this causes restriction of fuel flow..

if the problem persists,, have your fuel pump checked..

thanks,

Answer 2

If it only happens once a day I can't see it being anything serious. Maybe something drags on the propeller then releases again. ie. seaweed or an old rag or similar. Just a thought.

Answer 3

Have a look at the side of the fuel lift pump there should be an integral filter check to see if this is dirty .

If it is possible to get to scavenge filter in the bottom of the fuel tank check to see if it is dirty and slugded up.

Answer 4

Know a few people who experienced problems with Lister 3 pot air cooled engines. The fuel connections to the injectors come loose and cause rough running.Check your engine oil level,as when they start to work loose they let diesel into the sump.

Answer 5

Sounds like injector failure , have them pressure checked . you cannot do it in the middle of a squall

Answer 6

I'd go with the injector,as the knock and black smoke tell me it's a combustion fault more than a supply problem,also check that the valves are not sticking.

Answer 7

WATER IN DIESEL MATE

Answer 8

It may be something in the air filter. Check it