I’m lack­ing a bit of oomph

Canal Boat - - Back Cabin: -

QMy Volvo Penta 2010 en­gine loses power and when out of gear only revs to 2,500 (on the cable-driven me­chan­i­cal counter), when it used to reach 3,600rpm. I’ve changed the fuel fil­ter, done an oil change and there is the nor­mal amount of wa­ter com­ing out of the ex­haust. A REID, via email

ATONY REPLIES: If the wet ex­haust sys­tem is par­tially blocked it might still al­low the raw wa­ter pump to de­liver its full out­put, but back-pres­sure in the ex­haust may be lim­it­ing the en­gine power.

Dis­con­nect the ex­haust from the mix­ing el­bow and in­spect the el­bow for in­ter­nal fur­ring. Try the en­gine with the ex­haust dis­con­nected (it will make a real racket) – if you then get the revs, it’s an ex­haust prob­lem – prob­a­bly a de­lam­i­nat­ing hose. Also, try it with the air cleaner off. If that solves it, the cleaner is blocked. Be sure that there is at least 3 to 6sq in of vent area al­low­ing air into the en­gine area. I have had such prob­lems when boaters have used closed-cell foam on the deck board sup­ports.

Next, con­sider a lack of fuel. Did you turn the fuel tap back on fully af­ter ser­vic­ing the fil­ter? Is there a fil­ter on the en­gine or a wa­ter trap (which may con­tain a fil­ter or strainer) be­tween the tank and en­gine.

Is there a gauze in the top of the lift­pump? Is there a gauze strainer on the end of the fuel pickup pipe in­side the tank? Are all these clean? Dou­ble-check all unions be­tween the tank and lift pump to en­sure there are no slight air leaks.

It is pos­si­ble that the lift­pump is start­ing to fail: check by rig­ging a small grav­ity feed tank that sup­plies fuel di­rectly to the lift pump or fil­ter.

Check ex­hausts for in­ter­nal fur­ring

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