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Fish

Reoccurring Engine Failure / Deisel Problem

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We have a reoccuring engine failure due to a desisel / tank problem

Boat is a 25 year old yacht with an Izuzu 3 cylinder engine off a 120l stainless steel tank.

 

First failure (engine died) was approx 6 weeks ago. Since then we have replaced all fuel filters (3 times), replaced all fuel hosing, had a reoccurrance so drained deisel tank and pumped out with a pump for changing oil (5 litre capacity - good suction). Removed maybe 2 cups of water and deisel bug clearly evident. Found out the deisel additive we were getting from Repco was a performance additive and not for deisel bug. Now have deisel bug addtive - put in dissinfectant dose and top up on every fill.

 

Engine has run fine on several occasions (couple of club races). Topped tank up from 20l jerry can, ran for 3hrs from Weiti to Westhaven 16nm 3hrs - fine. Ran for 2miles this morning, engine died. 40litres in tank. Went into Orakie, topped up with 20l new deisel, engine ran 5min and died again.

 

The enigne runs fine when we disconnet the fuel lines from the fuel tank and bung the min a the 20l jerry can beside the engine. We have gotten home twice now doing this including today with several (5) miles motoring / maybe 1hr engine time.

 

We were very thorough pumping out the fuel tank and flushing it with fresh deisel then pumping it out again - ran fine for a couple of club races and 16nm / 3 hrs the other day.

 

1) There was heavy rain between delivering the boat to Westhaven and today, could rain water leaking in the filler pipe cause this? (Stainless filler cap in cockpit floor, looks Ok but has an old rubber o-ring on it)

 

2) We keep the tank less than half fill for racing, would condensation in the winter cause a problem this quickly?

 

3) is it possible the 25yr old stainless tank / difficult to access -has other problems and needs to be removed and cleaned out?

 

4) could it still be deisel bug?

 

5) am I going mad and should I take up golf?

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1) There was heavy rain between delivering the boat to Westhaven and today, could rain water leaking in the filler pipe cause this? (Stainless filler cap in cockpit floor, looks Ok but has an old rubber o-ring on it)

I'd only be guessing with the other ones but I have had a mate (Volvo in a 1020) experience the same symptoms with this issue. New O-ring sorted it out.

 

Bloody good effort running it off the jerry can. :thumbup: At least you know there's nothing wrong with the engine itself.

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check the breather on the tank

breather line looks sketch / hasn't been replaced. Filling up from a bouser today kept on blowing back almost constantly i.e. breather could be blocked (we normally full up from a jerry can).

 

Could a blocked breather cause this? vacuum in tank / fuel pump can't pull against it / act like no fuel = would re start on priming then die again... hmmmm

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Not always. Especially if a line somewhere has the slightest little means ofn sucking a bubble of air. Hard to imagine a breather getting that blocked, but it is indeed possible it could cause the engine to stop if it were.

I recomend you install a CAV filter unit. Cheap units that take a common cheapf filter element and has a glass bowl on the bottom that allows you to monitor water and also allows somewhere for water to accumulate.

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Fish, I'm no expert when it comes to anything mechanical but I can relate some issues I have just had with my 3 cylinder Volvo Penta.

 

I only bought the yacht in Jan this year. The mechanical survey showed up motor issues but it ran fine. We had the stainless fuel tank internally inspected and it looked clean. I used the yacht for a couple of months before I put it in to get the motor rebuilt without any issues.

 

When I got the yacht back we kept having problems with it running well for a while then either stopping and/or running rough. It would run fine for hours then just stop. it turned out I had two problems.

 

1/ The fuel tank was full of diesel bug. This wasn't there when I bought the vessel and only occurred within the few months of owning her. I also used to leave tank half full or less. The diesel bug was put down to condensation in the fuel tank. I had been using some dodgy old fuel additive that came with the vessel.

 

2/ Air leak in the primary fuel filter housing. This was a pig to find but we (i.e. the diesel mechanic) eventually found it by looking at the glass bowl on the fuel filter when the engine was at higher revs. You could clearly see bubbles forming.

 

From now on I always keep my tank close to full, especially over the colder months. I also use a good quality diesel additive. Apparently there are some real rubbish ones being sold.

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Fish the bowser blowback issue could be to do with the amount of air/froth/foam that accompanies the diesel as it's being pumped into your tank. When you are filling from a pump, the handpiece takes up most of the space available, and the fuel takes up the rest, so air in the tank can't escape out of there while filling - it has to go out the breather. If the breather won't let air out fast enough, you'll get blowback. You'll also get blowback if the filler hose doesn't go on a relatively direct line to the tank. A couple of curves and it starts to restrict the speed at which fuel can flow. My boat has a similar problem when filling from the bowser at Gulf Harbour, yet I can fill it as fast as a funnel will let it go from a jerry can. At Gulf Harbour you should avoid the high volume diesel pump and also try filling it at about half trigger on the handpiece.

 

Definitely keep your fuel tank full during winter. Len Gilbert used to say this every year in diesel diary. There are a number of good diesel additives but I use Moreys and can notice the difference when I don't. It has a bug killer in it. From what you are telling us, the problem clearly exists before the lift pump. You've replaced the filters, but what about the filter housing? I agree with Wheels, get a cav dual housing that has a water trap at the bottom and a filter element at the top. They're not expensive and you can see what's going on. Getting your fuel tank out could be a bummer but it may be necessary as diesel bug is a bastard to contend with.

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1/ The fuel tank was full of diesel bug. This wasn't there when I bought the vessel and only occurred within the few months of owning her. I also used to leave tank half full or less. The diesel bug was put down to condensation in the fuel tank. I had been using some dodgy old fuel additive that came with the vessel.

It takes much longer than that for a decent amount of algae to grow. Algae grows at the fuel/water interface. It lives in the water, but It has to have a source of nutrients and that is the fuel. But it can not grow in the fuel. There are two parts to the Algae or Bacteria. One is the living oranism and the other is the dead matter. It is the dead stuff that sinks down into the Diesel itself and it wil also coat and stick to the sides of the tank.

When you dose a tank to kill it, it will of course sink down through the fuel. A good slosh around in a bit if sea and the gunge in the tank sides gets flushed free and floats through the fuel and of course will always block a filter at the worst posible time. The other issue is that a small amount of acid is produced and this creates little pit area's in the tank for rust to start. Hence why the gunge of some bugs can be also quite rusty looking.

The simple method is, no water, no fuel. So being able to bleed of the fuel every now and then to check for water and get rid of it is a good idea. Keeping the tank full has pluses and minuses. Yes it stops tank breathing due to air heating and cooling. But at the ame time, Diesel fuel itself has changed over the recent last couple of years and it doesn't store quite so well anymore. The enigne will still run on it, but it does still tend to lose some of it's goodies.

However, a full tank is good for having a boat ready to go when you want, so it is well worth doing it.

One thing that I don't do and recomending having changed on any boat is to return the return line back to the fuel line just before the Filters and not returned to tank. The fuel is warmed throught the injector pump and some engines have a very high volume flow and that can add to having air suck into the tank as it cools later.

Oh and in realtion to filters. Filters are often made to be one of two types. A pressure filter or a Vacumm filter. If you use one that was desinged for after a pump (pressure) on the before the pump side, it is very easy to have air sucked into the filter, so make sure you have the correct type.

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It takes much longer than that for a decent amount of algae to grow.

 

That's interesting Wheels. Following your logic that means that I probably had the diesel bug algae/bacteria before I purchased the vessel but the dead matter wasn't visible at the inspection. The yacht had been sitting idle at the marina for a long time before I bought it so that is distinctly possible.

 

I had to get the tank cut opened and the fuel lines flushed based on the recommendation after a fuel sample report. Cheap is was not!

 

The BP report I read indicated you could store diesel for 6 months safely as long as the ambient temperature was less than 30 degree's. I only have a 50L tank so can easily use that in a 6 month period. The report was dated 2002 so I would be interested if anything has changed since then.

 

Here is the report if anyone is interested.

 

http://amsca.com/files/Download/Fuel_news_long_term_storage_diesel.pdf

 

Fish - If it were me I would consider getting a fuel quality report. This would at minimum cross of the diesel bug as a potential cause. As Wheels has mentioned, you ought to have a decent primary fuel filter with glass bowl for water/colour inspection. The secondary filter is normally quite fine and can clog up very quickly (I learnt this one was from last vessel that didn't have a primary fuel filter when I bought it).

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