filthy fuel fault factors phenomenal failures

[restless]

To cut a long story short, my beautiful 85L double skinned inboard tank was given about half a liter of filthy water from a Greek quayside tanker.
This was discovered when we needed to get to shelter when the seas picked up... thankfully restless is equiped with an emergency 8hp.

Anyway, as tohatsu / nissan 50 are being discussed, I'll share what happened next. After purging the fuel as best as could be done on the water, I drained the carbs and carried on. Engine was unhappy. Turns out water won't drain out of these carbs via the little screws very well at all. I drained them several times on the go, but when I stripped them there was still a mass of watery sludge in each bowl.

So in went a water seperator-filter unit at massive cost (remote island tax) and with clean carbs I would have thought that to be the end of it. However, it now starts well enough, but then needs a squeeze on the primer every minute or two to hold the revs, and I'm anly pootling along at 4-5kts (when towing the dinghy, which is pretty much always)
Also, it tends to stall all too easily when mooring, which can be embarrassing, especially if peaches is helming and there's a crowd on the quay She hates to have her perfect manouvering spoilt by a petulant old stroker.
So I can only assume that the weedy little diagphram pump is over stretched and struggling to get fuel through. (it was renewed last year).

The fuel tank is right at the back, the filter in the old fuel locker. It is not a big lift, nor distance. Looks like I'll have to add one of these low pressure pumps to give it just that little bit extra. (btw, anyone know how these little pumps pump?)
http://www.ebay.co.uk/itm/12v-ELECTRIC- ... 20c7cffa4b

Anyway, if any of you fine engineering types out there are savvy to some old indian tricks or something too glaringly obvious such that I've overlooked something, feel free to help me resolve this irksome issue.

[133bhp]

not sure how much pressure the float vlaves can cope without leaking? flow rate sounds doable, simple to hook up and try though.

I'd "try" a longer coiled run of tube in relation to the exit length from the tank, with more length and maybe a little higher, once primed the weight of petrol will tend to siphon the short run from the tank? at least tend to resist siphonng back. Also position the bulb nearer the engine for aded effect? Non return vlave inline?

I'm interested in the trip itself coming all the way from the UK I beleive? we need some greek pics:) do a write up eslewhere. (inc how added another axle)

[restless]

Hi 133
We hauled the boat down last year, I must get round to posting on the site. Done half a write up...
I've made a start of this years may trip,
http://www.ironengineer.com/mac/Stories ... index.html
again, must get it all up together.

[Bill McClure]

If your fuel line is losing its prime every few minutes, you most likely have a small air leak somewhere. Check the connections where you installed the fuel filter. Use teflon tape or some sort of goop to seal them to the barbs and snug up the clamps. There is also a fuel filter on the engine to check and clean if you haven't already.

Great write up on the trip to Greece. Hope to make it back to the UK for some canal cruising some day.

[ronacarme]

You mention dirty gas and sludge in the carbs.
You also mention a " squeeze on the primer" would keep the engine running briefly. I am not sure whether "the primer" refers to the rubber bulb in the fuel hose that we sqeeze to pump fuel from tank to motor before starting the motor......or to a manual primer device on the motor, that substitutes for a manual or automatic choke, to assist cold starting, by squirting a little raw gas directly into the carb throat.
My old Evinrude 9.9 had such a manual primer device. Punching it enabled starting the motor and repunching it would keep the motor running briefly, even tho bad ethanol laced gas had gummed the carb float valve closed and thus blocked the normal fuel path thru the carb float bowl to the intake manifold.
Could your dirty gas have similarly gummed up or damaged your carb float valves or adjacent jets and passages?
Ron

[restless]

Hi
thanks for the pointers. I've given special attention to all the hose fittings and they are tight as a drum. All hoses are new so the only possible weak link anywhere would be the poxy engine connection which is next on my hit list to replace.

I've fully stripped the carbs and checked all the jets & drillings and blasted them out with hp air. The fuel tank is brand new, and fuel gets properly treated with the anti~~ additives to avoid degredation.I put in a new filter with last seasons service, and it is always the first point of inspection. I'll check the float heights next strip, and I'm going to be playing with the idle screws too (following the other thread) however the bottom line seems to be that there is just not enough fuel getting to the engine.

It would be a reluctant complication to add a low pressure pump, however I seem to be running out of options.

Regarding bringing the boat back.. may be in a few years! Glad you liked the write up

[RobertB]

I have not worked on a marine outboard but my experience with carburator floats has included floats with holes in them (they don't float anymore) and carb bowls with crud in the bottom where the floats stick.

Also, are you sure all water/crud is out just by blowing passages clean? This may not dislodge particulate.

Also, based on my experience on the boat, similar performance based on a kinked fuel line.

[kmclemore]

If only they made Grose Jets for the Tohatsu. I've used these little-known valves for many years in my LBC's and they are a *permanent* fix to the leaky float valve problem. No needles, no seats... just a ball, which since it is constantly rotated, never develops any wear or 'lip' to begin leaking. Why the heck they didn't just make all float valves like this in the first place is beyond me. *sigh*

[K9Kampers]

Becau$e wear item$ create profit$ thru replacement $ervice!

[Boblee]

Really think you have an air leak and the fittings on the tanks to the hose fitting are where we have had problems seemed ok but rough idle etc.

If your fuel line is losing its prime every few minutes, you most likely have a small air leak somewhere. Check the connections where you installed the fuel filter. Use teflon tape or some sort of goop to seal them to the barbs and snug up the clamps. There is also a fuel filter on the engine to check and clean if you haven't already.

Unless your hose can hold pressure or at least vacuum no good looking further, pump it up and move fittings also check connection between motor and hose fittings especially if one is not original.
If pressure holds then it's time to move to needle seat? doesn't take much to lose vacuum it took some time to find ours but main indicator is losing prime.

[seahouse]

Ditto Boblee.

And, how easy is it to visually re-inspect the fuel filter/separator element? They will separate out water from fuel and filter the fuel for a long time, but they can become clogged quite quickly with mousse, mould, biofilm and other crud that might have worked its way past what looks like an otherwise thorough cleanup of the upstream components and tank (?)

Admittedly, I would expect that if this were the problem that the fuel pump should be able to collapse the squeeze bulb (I assume located between the separator and the engine?). Which is a symptom you have not reported. Which reiterates Bob’s airleak thought.

Also, is the fuel tank vent open and free? Is there another screen on the pickup sump on the tank draw tube that needs cleaning?

- Brian.

[restless]

Hmmmm.
Thanks for all the suggestions. Few manuals speak with experience!
all fuel lines are brand new. Didn't have this problem end of last season, or for the 80l of fuel used in the days prior to contamination. Since the issue I added my own brand of hose clip to augment existing clips, namely a double wire wrap n tourniquet twist with inconnel siezing wire. Gives an all round squeeze without any kink/flatspot that you can get with cable ties/jubilee clips. They also have a very easy relaxed run.
I have to admit I realy don't like my priming bulb, for a start it only works when the exit points skyward, and just seems all over the place. To boot, it too is new along with the rest o fit. At times it pumps n goes hard, other times it just sort of never gets more than semi hard. Very frustrating.
Trouble is, once I get back to the boat it is a return to the middle ages, any bits have to be flown and ferried, so I really need to get this nailed now so I can get the bits n tools before going back. Miss the days of having her on the drive

[Boblee]

Also, is the fuel tank vent open and free?

Yeah forgot about that one (got caught ONCE) and it will certainly test if you have an air leak on the suction too.
If you pump the bulb up and theres no leaks on the motor side of it, it is probably ok?, really do think it is the fittings between the hose and the tank as you appear to have been very careful with your clamps, what you have also done though I suspect is increase? the suction needed from the fuel pump to the tank by adding a filter.
The fact that your priming bulb is intermittent either sugests its faulty or again there is an airleak between it and the fuel in the tank but it could also suggest that the bulb has an air leak.
IMHO the problem is an air leak in the fuel line between the tank and the needle and seat? and it needs to be sorted prior to even considering moving on.
Still say my best guess is the fittings on the tank, had it for a bloody long time before I accidently found it it doesnt take much especially if increased vacuum is needed to lift fuel especially at idle.

[Bill McClure]

What you say about the primer bulb sounds like one or more of its check valves may not be working. They could be clogged with crud. Here's a link to a procedure for checking them: http://www.johnsonevinrudeoutboardmotor ... ction.html. Not sure if they can be repaired. You might just have to replace the bulb. They are relatively cheap compared to a fuel pump. Also check the obvious and make sure the bulb is in the fuel line so the valves pump toward the engine. It's easy to put them in backward if you've had the system apart. Good luck.

"The thing most obviously correct is the source of error." Anonymous, but probably an outboard mechanic.