It does sound like fuel & it seems when your tank level is down a bit??? So
empty the tank & make sure the line from it to the lift pump is OK;

(i) the anti syphon valve at the tank outlet, if fitted is free & clear???

(ii) The lines fastenings have no possible air leaks?? so when the tank is
full it does suck air but when low & having to lift the fuel higher it does???

(iii) The tanks air vent is free & clear??

If that's all OK, then start looking at the lift pump & the carb (the carb
has a little final filter inside where the fuel line enters the float chamber,
it's clear/replaced???

K


noah wrote:

On Fri, 11 Jul 2003 19:15:05 -0700, "Nancy"
no-spam.ask.me.and.we.can.talk.com wrote:

Hi all,

First I must apologize for my abrupt leaving a couple of weeks ago. I was
under a lot of stressors in life, and just let too many things get to me.

Now, onto the problem of my boat.

Boat is a 30' Sportcraft with twin 350 inboards.
Both engines start up and run perfectly with no problems. Have been out
salmon trolling all day (at idle speeds), come in and had no problems. This
past weekend I went out on a long range tuna hunt. (got 24 albacore off of
the Oregon coast, but that's another story. :-) ) Boat ran great going
out, trolled at 6-9kts all day. On the way back in however, after a quick
refuel (carried 40 gal. of gas in cans), about 24 miles offshore, the port
engine began cutting out and stalling. Ended up coming in on one leg
basically, with the port engine at idle speed only at best.

I figured the problem was some crap in the fuel filter, so changed that out,
and a few days later went out and did a short 15-20 minute trial run to test
it...problem seemingly solved, engine ran at full speed with no problems.

Yesterday, I take some friends back out to the tuna grounds (only got 21
fish, but were not out as long either :-D ). Both engines run perfectly,
troll a good portion of the day and running back in the port engine begins
cutting out again. I found that I could shut it down, let it sit for a few
minutes running on just the starboard engine, and then restart it and it
would run for a minute or two again then stall out again. It acts like it's
running out of gas. No sputtering, no smoke, not hot, just cuts out.

Both engines run off the same gas tank, the tank is built into the transom
and I've not visually inspected it yet (not sure I can get access to it with
any ease at all). But if it were a problem with the gas, or the tank, it
should be in both engines I would think. If it were a problem with the
engine only when it's warm, I would think running it for even 30-40 minutes
at speed would get it warm enough to present the problem. I took it out
today on the water and it ran perfectly for about 45 minutes. The ONLY
thing I've done is gas it up yesterday when we got back into port.

I have no real clue what to check next. It SEEMS to present when the fuel
tank gets down to a certain level, but without running it all day, to run it
down again, I have no real way to check that again...

Any ideas or suggestions of what to look for next? Carborator? Fuel Pump?

Thanks much for any suggestions anyone could offer up.

Nancy


Years ago, my 17' MFG I/O started cutting out whenever I throttled up.
It ran great at idle, or a little above.

I couldn't find the problem.

My last resort was to tear down the carb, where I found (what I think
was) a fly wing in the bowl. Apparently, when I throttled up, the
wing was pulled into the jet orifice, and the engine would die. If I
backed off, all was well. How it got there, I have no idea. When I
removed it, the engine ran well.

I would have the fuel supply checked, in detail.

Good luck,
noah

Courtesy of Lee Yeaton,
See the boats of rec.boats
www.TheBayGuide.com/rec.boats