XP25 motor slowing

[Terry Forshier]

When I start up the motor and take off I am really moving along and pushing a nice little wake out but after 10 minutes or so the motor seems to gradually start slowing and I start losing a few points on the tach. After about 45 minutes I have slowed top end from 2600 rpm to 2200 rpm. This is about a knot slower on the boat speed. Increasing throttle makes no difference. What I think is happening is that the fuel filter is clogging. I have not changed the filters in 150 hours , or since I purchased the boat in 2006. I have drained the bottom of the Racor and there was a little stuff in it but nothing that looked very bad. Anyhow, I am going to change the filters out and see. Anyone else had this problem?
I know this is a SAIL boat but we all know there is a lot more motoring in sailing than most of us would like to admit. Ha Ha...

[Craig Illman]

Terry - Sounds like a plan! You might just change the primary filter first, test, then do the secondary filter.

as Ron would say, "just a thought" !

Craig

[RV61]

Terry,
When I bought my 1986 I had similar issue with drop in speed and RPM from time to time. It was due to fuel getting to the engine. After changing both filters and changing out some old fuel lines and I also I found screen at the bottom of the pickup hose inside the tank and it was covered in crud thus blocking fuel intake. I removed the screen as I read on this board. Treated fuel with a biocide and added cetone booster. After that no issues. At crusing speed flat lake 6.00 to 6.3 knots. Have treated fuel and added cetone booster as needed since then and runs well.   

[Craig Illman]

Rick - Good point! That reminded me of another place to check. There's a screen in the bottom of the Facet fuel pump too.

Craig

[Stu Jackson]

And the fuel should run from the tank to the primary filter/water separator and then to the fuel pump.  Do the hose change if it had not been done before.  It takes less than 20 minutes to do.

[Ken Juul]

Another off the wall idea.  A friend has a Nonsuch 30.  Engine and fuel system set up is almost identical to ours. After 15-20 minutes of motoring he too would loose power.  After a month of trouble shooting we determined the bleed/fill plug on the top of his Racor was leaking air when put under suction.  It was excerbated when the tank was below the gravity flow level because after shutdown the racor would not refill itself.  It was hard to find because no fuel leaks were present.  It was a small leak, 15-20* of turn on the wrench tightened it. We surmized that the pump has enough suction to suck in air, but the fuel didn't have enough head to push fuel out.  So check all your fuel line connections, make sure they are tight.  Especially those on the Racor.

[steve stoneback]

There is one place you are suppose to be leaking air, the fuel tank vent.  If your fuel fill o-ring is sealing like it should, I doubt that small pump would have enough suction to draw fuel for an extended period.  I know it's highly unlikely that this is your problem, but you should make sure your tank vent is clear.

Steve

[Ray & Sandy Erps]

Although I would first suspect restricted fuel intake, as already mentioned, there is another possibility not mentioned yet.  An obstructed exhaust outlet, most likely at the elbow, could also cause low power problems. 

[Ron Hill]

Terry : After you have checked all of the items mentioned above and made sure that the injector pump is getting all the fuel it need; you might have a bad injection pump as I had. 
See my article in the Mainsheet Tech notes on the Injection Pump.  You have the same symptoms that I had.  A thought

[Terry Forshier]

Thanx for all the input. I finally got around to changing the RACOR fuel filter today. I did not change the filter on the motor as the Racor was pretty muddy when I took it off and I was impatient to see if it helped any.I did not get out on the bay but did run the motor for about 1/2 hour to make sure i did not get air in the line. I did notice that I was able to run up the motor at the dock (tied up) under load and the throttle showed noticable tach movements at all levels. Before it would run up then stall out at the top end and even if I increased opening the lever it made no difference.
Since this was my first time with this it took awhile to find the filter on the motor and the shut off on the fuel line. I was wondering if I change out the smaller motor mounted filter and refill the filter with fuel before I twist it on will that permit me to not have to bleed the line or will I still have to? I was able to do this on my last boat but it had a Yanmar 2QM15 that was a very forgiveable motor. When I next get out I will report on the progress.Now we are waiting to hear what the Tropical Storm over Haiti , Fay, will decide to do. Hopefully it will head North and pass us Floridians.

[Stu Jackson]

Bleeding your engine:

Terry, here's how to do it painlessly:  http://c34.org/bbs/index.php/topic,2884.0.html

To bleed after you change the secondary (engine mounted) filter, you need to bleed by opening up the nut on the top of that filter's housing.

[Terry Forshier]

tested today with the motor and changing the primary (Racor) made a big difference in top RPM's and speed. However after 15 minuted the motor again slowed a couple of ticks on the gauge. After we put this storm event (Fay) behind us I will try and change the other filter and see if that helps too.
Spent quite awhile preparing for Fay, taking off all the canvas and tying up across the canal etc etc. Will decide tomorrow if I need to remove the sails or just tie them down. Always something.
Terry

[Terry Forshier]

Day after the storm here and while I was putting stuff away I went ahead and changed the second filter on the motor. Started up and ,,,bad news, motor ran good a few minutes the started slowly surging. Checked the motor. Looked like maybe the fuel line was leaking where it went into the filter. Tightened it up and ran ok a bit then really surged. Slowed then sped up, then slow. Checked the fuel pump. the line out of the filter into the pump was bubbeling and squirting fuel. I Shut down and went to store and bought new fuel line. Will try that tomorrow. ..Always something. Now it is worse than when i started.

[Ron Hill]

Guys : With vintage boat of 20 years, I've already replaced my fuel line twice !! 
Take and look at a 90 degree bend or bend the fuel line to that degree.  If you can see cracks on the outside of that bend - CHANGE your fuel line!!. 
I'll bet that there are fuel lines still out there that are painted the same bronze color as the engine!!!   
A thought.

[David Sanner]

New fuel lines... good for use with B20 as well.

I had a similar problem but more abrupt, my motor, while
approaching the Golden Gate Bridge in shifty/light air and
and a fair bit of current suddenly slowed, as if someone had
bumped the throttle.  I was wondering what was going to
happen next but it just kept on running with about a 30%
power loss.

I was surprised how abrupt it was but still suspected it was
the primary filter as it had been over a year and had just
bounced up and down the coast.

When I got back to the dock I swapped it out, opened up
the self bleed valve all the way (I usually leave it cracked a bit)
and let the pump fill up the filter and unfortunately push air
through the system into the secondary filter.  After several
starts and stops the motor ran reasonably smoothly but still
wouldn't get full power tied to the dock, in forward gear, etc...
(Never quite gets full rpm stationary but that was noted)

However the next time I took her out and ever since I haven't
had a  problem.  Go figure?

My figuring is that there was a significant amount
of very tiny bubbles in the system, specifically ones that
where pushed into the secondary from the air in the
primary... another five minutes of running it at the dock
would probably have cleared many of them.

So lets hope your problem magically clears up like mine did.

btw, I'm leaving the option open that it was something
totally unrelated... temporary plug in the exhaust, bad
bit of fuel, plugged injector that cleared itself after the
motor cooled...  or something that only pops up after
a couple hours of motoring, something that I rarely do.

A new fuel tank and fuel lines, perhaps with an emergency
bypass around the primary filter, should be in my future...
when and if I ever have some spare time again.



Either that or my motor just didn't want to run on that day.
It certainly wasn't too hot or have any exhaust restrictions
that I could find.

I think the last time I change my Racor/primary I
hand primed the pump as I don't remember the
motor stalling out ever.

-d