It's Good to Vent
Q & A — July 2004
By Capt. Ken Kreisler
It’s Good to Vent
| A possible
cause for fuel starvation, diagnosing a spark plug deposit, and more.
have a 41-footer with twin gasoline stern drives. Lately I’ve noticed
decreased engine power and surging at higher speeds on one engine. Everything
seems to check out, but the problem reoccurs. Any suggestions? T.B.,
A typical vent system for an integral fuel tank, as illustrated here, includes a hose that leads from the top of the tank to a fitting mounted on the outside of the hull. Having a small orifice, this fitting is notoriously prone to blockage by debris, especially insect nests.
To determine if this is the source of your problem, loosen the fill cap enough to allow the tank to vent, and then run the engine. If all appears to be normal, a clogged vent is most likely the culprit. To clear the obstruction, remove the hose from the vent and push any debris through to the outside. Failure to do so can cause the debris to be sucked into the fuel tank and, eventually, into your engine, causing more problems.
a recent tune-up on my tender’s two-stroke outboard, I noticed a
deposit wedged between the electrode and the spark plug electrode. What
can be causing this? P.G., via e-mail
This article originally appeared in the June 2004 issue of Power & Motoryacht magazine.