Fuel Problem

[RNGONMT]

I have a J-36 with a Yanmar 3GM engine. The engine runs fine while motoring only but after sailing and heeling the engine will run about thirty minutes and quit. Have to bleed the fuel system of air and then will run fine. Have installed check valve at end of fuel line inside tank. Though maybe heeling was causing fuel to drain out of line causing air lock, doesn't seemed to have helped. Noticed secondary filter canister was extremely hot when went to refill with fuel. Raycor had fuel in it but not the secondary filter. What could be causing air to enter the system only while sailing?

[GordMay]

Greetings and welcome aboard the CF, RNGONMT.

[Maren]

Originally Posted by RNGONMT

I have a J-36 with a Yanmar 3GM engine. The engine runs fine while motoring only but after sailing and heeling the engine will run about thirty minutes and quit. Have to bleed the fuel system of air and then will run fine. Have installed check valve at end of fuel line inside tank. Though maybe heeling was causing fuel to drain out of line causing air lock, doesn't seemed to have helped. Noticed secondary filter canister was extremely hot when went to refill with fuel. Raycor had fuel in it but not the secondary filter. What could be causing air to enter the system only while sailing?

1) Could you include a photo or two?

2) That said, we had a similar problem a month ago. It turned out to be a couple of problems in contrast to the House adage of only being one bad thing happening at a time. Part of the problem was fuel. We had water, rust and algae in fuel. There was also a bit of rubber gasket that was recovered when he had the fuel polished. But what specifically pushed us to get the fuel polished was the fact that the engine quit while motor sailing and we crossed somewhat rough sections or when we were passed by a large fast moving motor boat while motoring ourselves. That helped, but didn't totally fix it.

What did fix it was replacing the hoses, even though most looked pretty good. Now, none of the hoses were cracked but some were stiff.

If you're sure you're fuel supply is good, go with the air leak option.

[RNGONMT]

So you're saying that air was entering the system through the dried hoses as they were being knocked around by the movement of the boat?

[delmarrey]

Originally Posted by RNGONMT

So you're saying that air was entering the system through the dried hoses as they were being knocked around by the movement of the boat?

Yes!

If the hoses are old they get hard and can leak around the fitting. So if the boat heels over the weight of the line maybe causing stress on a fitting allowing air to get sucked in. Most likely a line down stream from the lift pump on down.

BTW The secondary filter will get warm because it's next to the motor, and the return line (sometimes) runs back thru a bleed fitting on top of it.

And get rid of the check valve. It's just another thing to foul up the system. Even a screen can cause problems.

[ShaunJ]

Well said Delmarrey, you are sucking air somewhere.

[hugosalt]

Don't have much time now , but will try to relay my experience
number of years ago with my 3GM.
Same exact systems, would run all day if motoring...as soon as I sailed with more than say 10 degree heel (either starboard or port tac) motor would run for 10-15 minutes and quit. Would
bleed and then would run again no problem.
I had a few well respected mechanics go over and change whatever they felt needed changing after I had taken my best
shot...no one found problem...never found out what it was but
wound up changing all fuel del. system including fuel filter, fuel pump, entire racor unit and all hoses and fittings The only thing
original was the fuel tank itself.
Hopefully your situation will not be such an adventure.
I started by bypassing different filters by using a day tank (small aux. tank) and fuel line, the ones with the rubber bulb.
(rubber bulb good idea to install in line as will help when bleeding system even after problem solved.)
And then tried bypassing different filters and fittings...you get the idea. Took me 2 years and never found specific problem.
As you have to bleed the system more often you must be aware
that you can actually cause more air leaks as there are some copper washers (i think in the 2nd fuel filter) that are recommended by changed out. Will try to remember more and post when time allows.
Have kept daytank until recently as was always good for keeping a few extra gallons of clean fuel if conditions stirred up the nasties in the main tank.
Hope this helps.
Hugo

[hugosalt]

Yes surely an airleak.
I removed my screen in pick up tube, believe that is
recommended now.
Also while trouble shooting problem I kept tank topped off to
eliminate any question of tube sucking up air while boat heeled.