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Fun with Fuel

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  • Fun with Fuel

    Had some fuel-related fun the last couple outings with the 17' CC / 125 Optimax that I got from my Dad a few months ago.

    Outing the time before last, my nephew and I had just caught full air off a rogue wake, and the motor cut out just as we hit water (hard!) again. I figured maybe some water got up in the cowling, or a battery cable came loose, or perhaps my knee had just hit the kill switch (again) that the dealer my Dad bought the motor from--also the place that rigged everything--had strategically located exactly where my knee goes. (Kill switch has since been relocated.)

    After awhile, we figured out we were simply out of gas. But how can we be out of gas with 1/2 tank still showing on the gage? Well, later on I discovered that the fuel float sender that the same dealer installed was far too long (and thus too deep in the tank), and could not possibly register any less than 1/2 tank because the float would lay on the bottom--I have since replaced with a reed sender, much better...but I'm getting ahead of myself.

    So we called and bought 5gal of gas from the local on-the-water towing company I have a membership with, and that got us back to the dock. More on that later...

    Now then, before this last outing, as I was replacing the fuel sender, I noticed that the vent line was not connected to the tank, it was short by about 6", leaving a big open nipple on top of the tank. Thanks again, dealership, for leaving the fuel tank that way, while you were installing the wrong sender. I did install a bit of vent line and a brass union nipple between the tank and the existing vent line, and that did solve the mystery of why the bilge and console always smelled like gas. I always figured that smell was from that time my brother put 5 gallons of gas into the rod holder (and straight to the bilge), being that it is right next to the filler. And the time I did the same thing, though only 1/2 gallon before I caught it. Wound up filling 'er up while testing the reed sender vs. the gage, 2 gallons at a time, with Stabil, at the same gas station I always use for all my vehicles and toys--and from which I filled my truck just before filling the boat.

    So anyhow, last outing this past weekend, by myself. Got about 2 miles from the dock and the motor bogged down and quit, and wouldn't fire up again. OK, maybe the fuel vent is blocked, creating a vacuum the fuel pump cannot overcome, and that's why the dealer left the vent disconnected? So I cut the piece of line I just installed...no effect, still won't fire. Damn, now I have to re-do that.

    Then I thought that maybe, just maybe I had heard the faint Merc alarm over the din of the motor just before bog-out...4 beeps. Looked in the manual, and there's a table about 4 pages long of things the Merc alarm can tell you...and EVERY ONE OF THEM IS INDICATED BY 4 BEEPS. Thanks, Mercury. Very useful.

    I went through the table, looking for easily checked out things...hmm, "water in fuel"...it has rained a bit lately, maybe somehow a little water got in the tank?

    So I unscrewed the water separator canister...COMPLETELY full of water, barely even smells like gas. I poured that into a 5gal bucket, reinstalled the filter, sucked the canister full with the bulb, checked it again...ALL WATER. So I disconnected the fuel bulb at the motor and mouth-sucked another canister of water from the tank, then poured that into the bucket. Then another. Then another. Then another. All-in-all, I mouth sucked just over 2.5 gallons of water out of the tank before getting to gasoline. That took me about 2 hrs, and I was getting pretty high on gas fumes at that point.

    Still the engine would not fire. Well, if it was carbed, I could just drain the bowls...but DFI? Damn, actually, have I just killed this motor...or at least the fuel system?

    After another hour recovering from my suck-a-thon and looking over the powerhead, I discovered on the back of the motor that the fuel rail hose connects to the gigantic pump mechanism using a simple bolt and retainer (parts 4, 7 and 8 in this diagram):


    I undid the bolt, pulled out the hose, primed a number of times with key-on until fuel (instead of frothy white mess!) started to shoot out the hole, buttoned her back up, and BOOM, fired right up! Then I got the hell out of there, just as channel 16 was announcing Naval maneuvers commencing right where I was stranded, and a fleet of PT boats was bearing down on me...whew, just in the nick of time! I then ran her a solid hour or so without incident, just to make sure ALL the water was out of the places it shouldn't be.

    SO where did all that water come from? Not the gas station, or my truck would not run. Not the rain, this thing sat through FAR MORE rain than that in December and January, and that was BEFORE I hooked up the vent line. The vast, vast majority HAD to have been from the 5gal jerry-can the towing co. brought me the outing before--and it had simply had time to settle out after a few weeks. Thanks towing co., for selling me 1/2 gas and 1/2 water. (Or thanks fuel dock, for selling THEM 1/2 gas and 1/2 water...)

    I guess the moral of the story is...trust no one?
    Last edited by ajgraz; March 6th, 2017, 01:27 PM.
    San Diego, CA "The 619"

    2000 Sea Hunt Triton 172 CC, 2014 Mercury OptiMax 125

    "It's always easier to ask forgiveness than permission" -Colin Powell, et.al.

  • #2
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    Corrections, and an update:

    Actually, only a few of the warning sounds are 4 beeps, the vast majority of the Merc alarm readings in the chart are one beep (still not so useful, I think). But to be honest, over the sound of the motor and the wind whipping through my fishing lines, I couldn’t tell you whether there were four beeps, one beep, or no beeps. Plus, as my wife would attest, I’'m half-deaf anyway. I do wish the alarm was louder.

    Turns out that gigantic fuel pump assembly in the link above does function something like a water separating filter; it has a draincock on the bottom specifically for draining water out of the under-cowling fuel system…...but it requires a 1/8” allen key that I did not have onboard--—though I will now!

    So I went back in to replace the section of vent hose I cut…, and I noticed that the cork gasket that came with my reed sender was split, apparently when I tightened the sender screws. So now I’'m thinking that a good bit of water did get in that way, seeing as how the top of the tank is shaped a bit like a funnel leading down to the sender opening...…nice. I guess that means the 8"” screw-down plate over the tank must be leaking like a sieve, and must be resealed or replaced with something better. Also I’ve got to find a rubber gasket to replace the cork.

    Boats are a definite PIA
    San Diego, CA "The 619"

    2000 Sea Hunt Triton 172 CC, 2014 Mercury OptiMax 125

    "It's always easier to ask forgiveness than permission" -Colin Powell, et.al.