Start and stop

"The 20-horsepower Yanmar in my Orion 27 has low hours, but last summer it began to stop about a minute after it started. When I tried a restart, it was clear to me that it was being starved for fuel. I bled the fuel line, and, when I saw air bubbles coming out at the secondary filter, I thought I’d fixed the problem. But when I let the engine sit unused for a couple of days, the start/stop
Author:
Publish date:
Updated on

"The 20-horsepower Yanmar in my Orion 27 has low hours, but last summer it began to stop about a minute after it started. When I tried a restart, it was clear to me that it was being starved for fuel. I bled the fuel line, and, when I saw air bubbles coming out at the secondary filter, I thought I’d fixed the problem. But when I let the engine sit unused for a couple of days, the start/stop problem reappeared.

Your book Marine Diesel Mechanics has some helpful ideas, but nothing you mention in it seems to explain my situation; I know there are no fuel-line leaks or poorly seated gaskets. I did notice that the problem occurred when the fuel gauge showed half full, and the problem seemed to go away after I topped off the tank. You mention return-line siphoning in your book, and I wonder whether the half-full tank is letting air get into the line."

-- Karl Westman, Ocean City, New Jersey

Nigel Calder replies: If return-line siphoning is the problem, it will occur no matter what the fuel level is. Although I’ve never been able to prove it, I believe that fuel-line siphoning takes place when fuel dribbles down out of the return line over time and lets air work its way up into the system. At least I think that’s what happens. That’s why I’m curious that you don’t get return-line siphoning when the tank is full.

If your fuel tank is located below the engine, the lift pump may be having trouble lifting the fuel when the tank is half full; that could make the engine become starved for fuel. You should also check the lift pump itself to find out whether its valves are leaking. But before you do anything, make sure the fuel-tank vent is not plugged. An insect nest in the vent, for example, will create a vacuum when the fuel level drops, making the lift pump work much harder. A plugged vent will create a vacuum only after the engine has been run for a while—the tank will equalize when it’s at rest—and that’s the opposite of what you’re experiencing. But since it’s so easy to do, start by checking the vent.

Related

FamilyCruise

Bareboating on Puget Sound

Depending on where you are, Puget Sound can look no bigger than a mountainous version of the Intracoastal Waterway. That’s what I thought when I first laid eyes on it from the lighthouse at Mukilteo Park on a sunny day last July. Then I went to the top of the iconic Space Needle ...read more

Bali4point1

Boat Review: Bali 4.1

Coming fast on the heels of its predecessor, the Bali 4.0, the Bali 4.1 adds a number of improvements, many of them inspired by feedback from owners and charterers. She’s an evolution of a concept that has already proven popular and very many benefits from its builder’s ...read more

Headsail

Ask Sail: Silencing A Rattling Headsail

Q: Our Pearson 26 has a 110-percent jib that tends to rattle very noisily at the top hank. We only bought the old boat recently, but it must have been happening for a long time, since there’s a deep groove worn inside that bronze hank. The jib has an unusually large and wide ...read more

Alerion2048x

Alerion Yachts 33, the 90 Minute Get Away

Easy to sail, luxurious, and swift; the Alerion 33 is the solution to your busy life. The intuitive, simple rig design, easy set-up, and put-away mean there’s no need to wait for crew to enjoy a weekend, a day, or an hour out sailing. Her beauty and comfort are evident in the ...read more

anchor

Know how: Ground Tackle

Your ground tackle is like a relationship—the more you care for it, the longer it will last. So, how do you enhance the relationship? First up, think of the accommodations—a damp, salt-rich, often warm environment, just the kind of thing to encourage corrosion. What can be done? ...read more

DSC_7522

Boat Review: Beneteau Oceanis 46.1

The Beneteau sailboat line has long represented a kind of continuum, both in terms of the many models the company is offering at any given moment and over time. This does not, however, in any way diminish the quality of its individual boats. Just the opposite. Case in point: the ...read more

shutterstock_1016585167

Cruising: Memories Made by People You Meet

Steve greeted my boyfriend, Phillip, and me as soon as we tied Plaintiff’s Rest, our 1985 Niagara 35, up to his dock on one of the Berry Islands in the Bahamas. He was tall, cheerful and clad in a hodge-podge of clothes one might wear to paint a house: oversized, grungy and old. ...read more