Water in the tank; why did the engine run at all ?

[barrett bonden]

Why did the engine run at all ?
A 1977 Atomic 4 in a 27 foot Columbia. Boat had sat all last summer. Engine started and ran fine for half an hour, got us 200 yards outside the breakwater ( not a rough sea, but more motion than in the harbor) where it quit. I pulled a fuel line; lots of water in the gas.
Q: Why did it work at all ? Assuming the fuel/ water mix homogenized out of the harbor and got drawn into the pump doesn’t tell me how to prevent this on the next boat. Where is the intake on most tanks ? Water sinks to the bottom of course, and I assume the intake is at the bottom of most tanks; in that case I never would have left the dock.

(not my boat, BTW !)

[Kurt]

Without knowing the specific set-up on this boat, I'm guessing that if it has a Racor or equivalent fuel/water separator filter that the filter did its job until it became full of water. Crud in the fuel tank, including water, will often become problematic when the motion of the ocean stirs things up so that might have played a role as well, as you suggest.

[Marian Claire]

I believe most pick up tubes are not at the very bottom of the tank. One member needed to add more than 1 gal of gas to a empty/dry tank to get to the pick up. The PO told me there was a couple of gal below the pick up on the MC. Dan S/V Marian Claire

[Bold Rascal]

Similar story

I bought the old Bristol 27 which had a 2 stroke outboard in the lazerette. Engine fired right up and ran fine during our pre-purchase survey. Bought the boat, (very happy) next day warmed up the engine prior to going out for a lil spin. Engine ran a good solid 15 mins at dock idling just fine, no issues, off we go.
15 min's later, a 1/4 mile up what we now call "S**** creek" the engine dies, restarts, dies, then no restart at all. Grounded in mud, tide going out, starting to rain, you get the picture.

Pulled the engine, took it to a mechanic (Tohatsu) and 3 days later the guys calls me and says he's never seen so much vegetation in a carb.

Guess some of it just finally broke loose and that's all it took.

Still have the engine, keep it maintained, very reliable and runs great.

[Mo]

Check this out.

Something to look at:

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[positron]

The pickup tube in the gas tank on my P30 was shortened by one of the POs so it is about 4" above the bottom of the tank. I think this was an attempt to avoid picking up crud. So I run out of gas even though I still have 3 gallons left. There can be an amazing accumulation of sludge, water, etc. in a gas tank. One of the best defences is to run your engine regularly, so you cycle through the gas in the tank. I also empty my tank every fall, mostly to get rid of any sludge in the tank.

[Mo]

I use my boat almost every day. Have to say the engine only runs about 3 to 5 minutes to get off the dock and the same to get back on. This spring has been exceptionally fine and for the 280 nautical miles I have on the boat so far I have 8 engine hours...that's since April 30th of this year.

I agree, running the engine and using fuel helps keep the system clean. I also believe the best defence is avoiding ethanol fuel.

[Loki9]

I also believe the best defence is avoiding ethanol fuel.

Unfortunately, in many areas of the US that really isn't possible.