Hi Jim-
The new filter fixed it! It used to be a little paper "basket"
type, but this time they gave me one of the porous metallic
ones. I placed the convoluted side towards the fuel pump
to give the debris more surface area to run up against- I
assume that was as intended.
I did not fill the water separator with fuel, but it sure
didn't act like that was the problem. I would have thought
that would have made the engine hard to start right afterwards
but wouldn't account for the high speed/surge issue that
showed up for the first time a couple of miles out after
installation.
I wondered about something though. The filter was
inserted into a chamber against a spring, with a large
concave nut behind it (with a threaded hole for the
compression fitting for the fuel line to be inserted.) (Man
is a picture ever worth 1000 words!) How does that spring
keep the filter from bouncing when the surge of fuel from the
fuel pump hits it and possiblly passing minute debris into the
carburetor? (Sorry, that's the only way I know how to ask
the question!)
Many thanks again for your great advice!
Frank





On 1 Aug 2006 08:27:24 -0700, "jamesgangnc"
wrote:

I would change the filter if I had thsi problem. I agree it doesn't
completely fit the symptoms but you want to eliminate it. Make sure
the flow direction is correct when you install the new one as they clog
quickly when installed backwards.

Was the water separator a screw on? Did you fill it with gas before
installing the new one?

Surging often is a gas issue but nothing is 100% certain. Boats are
more likely to have fuel system problems because of water. It corrodes
things in the whole fuel system.

frank1492 wrote:
Thanks Jim. Yes, now I understand why it couldn't have been
a line problem with symptoms as I described them. (Also, I
checked the screen at the tank and everything was fine,
but I now know why that was pointless, at least with the
problem as originally described!)
Now, however, there seems to be a new wrinkle. Today
I observed the same cyclic fuel starvation behavior *without*
the wave motion! At low speeds it's fine, but at about 3000
rpm it will start to oscillate- sometimes. I'm now inclined to want to
check the paper filter just ahead of the carburator, but I'm
still wondering. If that was partially clogged, I would think
it would simply starve the fuel whenever the boat was
accelerated, and stay that way until the throttle was
manually retarded. This is like a feedback issue, as if
there was debris sucking against the inlet at high speed,
which would relax as the engine faltered, allowing the
speed to increase again, and so on. Or would the problem
still be consistent with a carburator issue? (Yep it does have a
carburator.)
It seems that this really shouldn't be too hard to figure.
Unless you think it's really unnecessary, I'll change the
filter tomorrow.
OH- one more complicating factor. Although it's
probably just a coincidence, I had just changed my in-line
water separator. Didn't have the problem before that.
Thought I had better mention in the interest of completeness.
Frank







On 31 Jul 2006 08:45:01 -0700, "jamesgangnc"
wrote:

If the float(s) are set too low in the carburator it could cause this
sort of symptom when the boat is pitching for and aft. Normally the
fuel level in the carb float bowl should be high enough for the jets
and passages to stay submerged in fuel at any boat position. But if
the pitching is violent enough or the float level is low that could
cause the jets to momentarily be out of the fuel.

The reason I dismissed the tank pick up is that in a normally
carburated engine the float in the carb decides when to let gas in. A
mechanical fuel pump is always pumping and even it is momentarily
unable to get pick up gas from the tank that would not be noticed at
the carburator unless you were close to full throttle and using a lot
of gas.

You never did tell us if it was carburated or fuel injected. I assumed
carburated but that would make a difference in diagnoses.

frank1492 wrote:
Thanks to you all for your ideas. At the present time. I tend to favor
the fuel solution. If it was electrical it would not be in exact "lock
step" with the hull's attitude. As to the question of whether it
occurs in the "stern up, hull down" part of the cycle or vice versa
I will have to check for certain, but I would guess that was the case.
As to the low fuel solution, the first thing I will do is check
to see if the guage is reading correctly. It currently reads 1/4 of a
tank but I have had trouble with the sensor before. It is entirely
possible that it's much lower.
Once in the past I had an issue where a piece of cellophane
was bouncing against the fuel intake in certain attitudes and speeds.
So I will look there next.
If it were something in the carburetor, what would it be?
And finally, the fuel pump was mentioned but I didn't quite
understand the implication.
Got a good calm morning here so will go out soon and get
started. Will keep you all posted!
Frank







On Sun, 30 Jul 2006 04:56:20 GMT, frank1492
wrote:

With each "push" of a choppy following sea, the Chevy V6 in my 22'
Grady White I/O seems to want to die. This also happens when the
boat gets into any kind of a repetitive wave pattern. It is as if
something cuts off the fuel supply as the boat surges forward, and
restores it as it goes up the crest of the next wave. (Something in
the fuel tank perhaps?)
If it isn't something in the tank, where else would I look? What-
ever, it is definitely a function of up-and-down hull motion.
Your help is much appreciated! Thank you!
Frank