The fuel won’t get pumped up

Canal Boat - - Back Cabin - IAN SUT­TON, TONY REPLIES…

I have a Nanni Diesel 4.150HE en­gine that has a small pump on the side with a hand lever for prim­ing. I have pumped the lever sev­eral hun­dred times over the course of an hour with­out any fuel ar­riv­ing at the main fil­ter. I don’t fill the pre-fil­ter (wa­ter sep­a­ra­tor) with fuel be­fore fit­ting as the fuel would leak out the bot­tom be­fore the bowl is tight­ened. I also don’t fill the main fuel fil­ter be­cause I pre­fer to have clean fuel fill­ing it via the pre-fil­ter. How­ever, I was tempted to fill it with the fuel from the old fil­ter to cut down the num­ber of times I’m pump­ing away on the prim­ing lever. Can you help?

via email

QThere’s one po­si­tion in ev­ery two en­gine revs that will ren­der a me­chan­i­cal lift­pump all-but in­op­er­a­tive. En­gines tend to stop in only one or two po­si­tions, so if yours is stop­ping in that po­si­tion, op­er­at­ing the prim­ing lever won’t de­liver much fuel. You can tell if this is the case be­cause the lever will op­er­ate with very lit­tle re­sis­tance.

First, try turn­ing the en­gine over one com­plete

Aturn and re-try­ing the lever with a bleed screw open. Also, pump­ing like fury will have lit­tle ef­fect, it re­quires long slow strokes.

If that’s not the prob­lem then ei­ther air is leak­ing in be­tween the tank and lift­pump or the pump is faulty. Turn the fuel tap off and dis­con­nect the fuel pump out­let. Spin the en­gine on the starter while catch­ing the fuel de­liv­ered. You should get at least half an egg cup per ‘squirt’. If it is less, then ei­ther the pump is faulty or there is a block­age be­tween the tank and pump. Try blow­ing back down the pipe into the tank.

Next dis­con­nect the in­let pipe on the pump and put your fin­ger over the in­let. Spin the en­gine on the starter for a few rev­o­lu­tions. Pause 30 sec­onds and take your fin­ger off. The pump should have held a vac­uum. Do the same for the out­let but this time it should have held pres­sure. If it fails on ei­ther count, the lift­pump is faulty. It might be cheaper to leave the faulty pump in place and fit an elec­tri­cal lift­pump fed from the ig­ni­tion switch. Facit is one read­ily avail­able make.

If the fuel pump is okay, look for air leaks. The Beta ver­sion of your en­gine is self-bleed­ing, so if you com­bine a small suc­tion from the el­e­ments in the in­jec­tor pump with the fuel head in the tank, the en­gine might bleed suf­fi­cient air back into the tank to al­low it to run.

Don’t fill the new fil­ters with fuel from the old fil­ter, but it will help the bleed­ing im­mensely if you do fill it. Buy a small amount of fuel from a fill­ing sta­tion.

Newspapers in English

Newspapers from UK

© PressReader. All rights reserved.