both diesel engine shutdown simultaneously

[timjet]

Thanks HopCar. Yes I check that, one of the first things.

[jleonard]

In this particular case if it had been an air leak I don't think the engine would have started back up right away without having to purge the air out of the injector pump.

The Bosch 7100 series pump on the Cummins 330 is self bleeding. They would purge themselves in a revolution or two of the engine.

[timb7734]

I had a Mainship Pilot twin before I had the current trawler built, it was a 2001 model. I would say the boat in the original post had a fuel tank issue, as these engines burn fuel at a greater rate than the engines in trawlers, for example, and either recently putting aboard a bad lot of fuel, or having a contaminated tank appear the issue, and under the circumstances both engines would go simultaneously.

Very bad for any modern Yanmar to be fuel starved, as the injection system depends on lubricity and cleanliness of fuel for lubrication as well as the pressures involved require extremely close tolerances. I believe the engines shut themselves down when fuel starvation is sensed.

Best course of action is to treat the tanks with STARTRON, available at West Marine or any good chandelry, and buy some extra filters. Startron will kill the algae, and liquify it to the point that the filters will remove it, but be prepared to change a few more. Then treat the tank pro actively anytime the vessel will sit for more than a few weeks in high temperatures or where day and nightime temps vary a lot. If you use Startron as I have for the past several years, you need not even keep the tanks full.

I have been in the trucking business for 40 years using heavy diesel engines, and as a matter of course diesel fuel loses 1% of it's cetane value each month in storage. Rather than keep a boat full, treat a low level of fuel when the vessel will sit, and fill up with fresh fuel when you depart for the next cruise.

[timb7734]

My trawler burns 1 GPH per engine on twin Yanmar 74 hp engines, at 7.5 knots without the gen, and it holds 1000 gallons, and I fuel once, maybe twice a year and treat it. I have never had any of the Racors show any pressure increase over their 500 hour life on the filter mounted gauges. The Mainship Pilot with the 250 twins burned more like 6 GPH with the same filters, the Racor 500's spin ons with the sight glass bottom.

I also have an express boat in the Great Lakes with twin 700 hp cats that burns 18 GPH per engine at low cruise, and I have been the recipient of a bad load of fuel that caused both engines to simultaneously drop to idle with two Racor 1000's, both open on each engine.

[FlyWright]

Originally Posted by timb7734

My trawler burns 1 GPH per engine on twin Yanmar 74 hp engines, at 7.5 knots without the gen, and it holds 1000 gallons

Not to hijack this thread, but I'd love to see pix and specs on your trawler.

[timb7734]

I put a couple photos in an album

[petersmarine33]

Hello. Sounds like you might have diesel bug. This multi-type organism thrives on carbon fuels and lives at the interface of the diesel and condensation water in the tank. When it dies, it produces a stringy type bio-mass which gets sucked up the fuel delivery line and blocks primary filters. This usually occurs when you need it least !!
Are you running from a single tank?
Original fuel source is usually the main suspect, especially when fuel has ben stored for a long period of time. Often now, fuel producers cut mineral diesel with a percentage of Bio-Diesel. (from 7 to 11%)
Bio-Diesel is more hydroscopic than regular diesel so attracts the water out of the atmosphere the bug needs to survive on. Bio-Diesel also wrecks regular neoprene gaskets and pipes, with the resulting chaos.
The "shelf life " is less than 3 months !! before it begins to seriously degrade.You can even get the bug spores from a wet deck after a rain shower. It only needs a minute amount to cause havoc in your fuel system.
There are test kits to acertain whether or no you have a problem. A smell of sulphur or bad eggs from the diesel will also confirm the worse.
There is also available diesel tretmant compouds, but be sure to get the correct one as some of them are very expensive and ineffective.
I could go on and on about this subject as it is a bete-noir of mine.
Happy to clarify any points if required.
Good Luck with it, Regards, Peter.