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Fixing Fuel Starvation
by
Steve Horsfall
I
have a 115 hp V-4 on a 19-foot runabout. At the end of the season,
the engine would lose power at full throttle. Everything was fine
up to 4500 rpm, but, when I went to wide open throttle, the engine
lost power and would stall unless I throttled back. After a few
seconds at idle, it would run as before.
Is there
anything I can do to check this out myself?
D.
Field, Pembroke, Ont.
The problem
you are experiencing definitely sounds like a fuel starvation. There
are several things that can cause this. Here is a brief rundown
of things you can look into.
1] Check
and replace fuel filter.
2] Is
the engine running off a built-in tank?
2a) If
so, try running on a portable 25-litre o/b tank.
4] If
the problem goes away, check the vent on the built-in tank to see
if it is clear. Remove the filler cap and retest.
5] Check
for an anti-siphon valve at the fuel pick-up. Remove valve and re-test.
If the engine works ok, replace the valve.
6] Run
a separate hose from the built-in tank to the engine. If engine
works ok, replace fuel line. It could be internally collapsed.
7] If
problem still occurs while running on the portable tank and the
filters have been changed, I would recommend getting your mechanic
to clean and service the carburetors and check the fuel pump pressure.
(Top)
Dialing
in for performance...
First let me say I am new to boating. We purchased a 1986
26' Chris Craft Classic last July. With the limited boating season
last year on Lake Simcoe, we did not get to know the boat as well
as I'm sure we will in the coming year. I could write a book of
questions, but will bother you with only one for now.
Since the
boat is a 1986 model, the operating manual was nowhere to be found.
It has a MerCruiser Alpha One, 230 HP V8. What I would like to know
is at what rpm should I be operating the engine? Top end seems to
be about 3000 rpm, which gave 24mph by GPS.
Can you
shed any light on this? Any information would be much appreciated.
J.
Beatty (e-mail)
With regard
to the operator's manual, if you write down the serial number of
the engine and take it to any MerCruiser dealer, they can order
one for you.
As for the
engine speed, the engine should be propped to turn about 4300 rpm
at W.O.T. (wide-open throttle). First have the tachometer checked
for accuracy. If it will only run 3000 rpm at W.O.T., and the engine
and the tachometer is working properly, it probably means the propeller
is too big. My guess is you should be running a 15-17 inch pitch
propeller.
If the prop
is in this range, then there could be a problem with the motor.
Fuel starvation, ignition miss, etc. If the propeller is larger
than 17 inch pitch, it is probably not the right prop and should
be changed.
When the engine
will run at approximately 4300 rpm at W.O.T., then your cruising
speed would likely be anywhere from 2400 to 3200 rpm for best efficiency.
You should be running just a little faster than it takes to stay
on plane, but below 3/4 throttle position. (Top)
Tough and
pretty floorboards...
Thank you for your advice in the past. I found that it came in
very handy and helped me tremendously. I have one more concern,
I recently fiberglassed my dinghy floor boards. I did this because
I find lots of water in the dinghy after towing or after a rainfall,
not to mention other boaters' wakes.
Now that
the floorboards are fiberglassed, I was considering painting them.
What must I do? What steps are involved, and what kind of paint
must I use? I was told that the kind of resin used makes a difference.
I used fiberglass liquid resin that contains polyester resin and
styrene, basically the kind used for cars. I bought it from a major
retail outlet.
H.
Stromboulopoulos (e-mail)
You can paint
them with an epoxy paint, but, if it was me, I would mix up the
same fiberglass resin you used to coat them with and add fiberglass
color pigment to the resin. Mix thoroughly, add hardener and apply
with a brush. Usually two coats of resin will color it completely.
Color pigment
is available in basic colors at major outlets. Try where you bought
your resin. This will provide a very durable finish, much more abrasion
resistant than paint. Given the wear and tear on floorboards, I
think it would be a better finish. (Top)
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