[C320-list] Yanmar trouble

[Rick Sulewski]

Don't know if the Yanmar fuel system is fed by gravity as is the case with
my Westerbeke engine....but that could explain how you ended up with air in
the system.

I had a fuel pump that was not working due to a loose power wire that had
parted. I did not know that at the time my engine quit working but that was
and when the fuel tank went to around a quarter of a tank, or around the
level of the fuel pump, and the engine stopped. I thought that my fuel gauge
was faulty and had to dock under sail. After adding only a gallon fuel, the
engine fired right up! Come to find out that after I noticed the engine
running but I could no longer hear the fuel pump clicking, I was motived to
learn why the fuel pump was not working. I ran down a parted hot wire to the
fuel pump that was spliced when the fuel pump was replaced a few years
earlier.

 Just saying that you may want to check to see if your fuel pump clicks
periodically while your engine is running, or at least that's what happens
on a Westerbeke. On my engine I can test to see if the fuel pump is working
by by-passing the oil sender switch as when there is no oil pressure, the
fuel pump relay shuts down the fuel pump. However, if I bypass the oil
sender switch by connecting the two spade type connectors together, then the
fuel pump will run when I turn on the key. 

In your case, perhaps adding fuel to the system allows the engine to be fed
by gravity providing the injection system with just enough fuel to be placed
under pressure to feed the cylinders and the engine runs. However, once the
fuel pump (serving as lift pump) no longer works, the level of the fuel in
the tank may determine how long the engine will be gravity fed.  After
fixing that loose fuel pump wire I noticed an increase in engine power and
acceleration because the fuel pump served to move more fuel to the injection
side of the fuel system where the fuel is placed under high pressure to feed
the nozzles. 

If you are having a fuel pump issue, that could explain why you had air in
the system before the fuel was added to the tank and then the fuel found its
way to the injector and it fired up.

Rick My-Ria
95 320 #277

-----Original Message-----
From: C320-list [mailto:c320-list-bounces at lists.catalina320.com] On Behalf
Of dprudden
Sent: Wednesday, August 06, 2014 7:46 PM
To: C320-List at Catalina320.com
Subject: Re: [C320-list] Yanmar trouble

Thanks to all for the suggestions.

I started by checking the Racor primary for dirt/water but the fuel looked
good....and there was fuel. I next checked for air in the lines. There was
some so I bled the lines, added 4 gallons of fuel, tried starting, and after
a minute or two of rough idle and stalling, she smoothed out and is running
fine (20 minutes at dock then 1] hour round trip for topping off tank).
Somehow air got into the fuel line. I definitely had a 1/4 tank left and it
was flat calm in the middle of a 9 hour motor across Cape Cod Bay (no wind
at all!!) If I hit a wake, is that enough to slosh the diesel in a 1/4 full
tank around enough so a bubble or two of air gets in the line? 

Thanks!!!

David Prudden
#787

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