Yanmar cut out, re-starts, runs, then dies

matt1

matt1

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Firstly, apologies to those on the river Hamble this evening who had to endure me short-tacking all the way against the nw'ly onto my berth, especially the chap in the speedboat shaking his head in disapproval :) my engine failed off Calshot so I didn't have any choice. At least it was a weekday and not Sunday afternoon :)

Anyway, engine suddenly loses revs and cuts out. I determine we haven't fouled the prop and restart the engine. It runs very erratically for 20 seconds then stops. I tried it 2 more times, once coming into the river and again when I was back on the mooring. The last time it restarted fine, ran smoothly for 30 seconds then lost revs suddenly and cut out again. I'm thinking its a fuel issue. Any ideas? Engine has 520 hours and is otherwise trouble free. It's a 3YM20

Matt
 
Does it run at tickover and only when you put power on does it stop or what? Did the mechanic change both primary and secondry filters (if you have them)?

I'm no mechanic but it's either fuel, air or compression that will stop a diesel. So I'd start at the fuel and check the filter, bleed the system incase there is an air leak at a joint. also check the air filter. There are some diagnostic procedure in the YM workshop manual which should help.

Good luck.
 
Think he probably just changed the primary filter. If there was a pattern to it dying it was perhaps when throttling up past 2,000 rpm
 
How long does it run before it first cuts out? If you have either or both an ailing lift pump or blocked tank breather you can get those symptoms. You could try testing with a temporary 'day tank' high enough to gravity feed to isolate the issue.
 
Norman_E said:
Well done for tacking it back in and not just calling for help.
Click to expand...

Thanks, although it's fair to say my fellow river users weren't impressed. To be honest it did feel a bit antisocial (it was fairly gusty and I'm sure i was annoying, but didn't have any choice)
 
Billjratt said:
How long does it run before it first cuts out? If you have either or both an ailing lift pump or blocked tank breather you can get those symptoms. You could try testing with a temporary 'day tank' high enough to gravity feed to isolate the issue.
Click to expand...

Cuts out after about 20-30 seconds I guess. Some good ideas to try and certainly the breather would be very easy to check. Thx
 
matt1 said:
Cuts out after about 20-30 seconds I guess. Some good ideas to try and certainly the breather would be very easy to check. Thx
Click to expand...

Obvious first thing to check is the fuel supply, as others have said. If not filters then maybe blocked or clogged fuel pipes. My boat's suffered a bit from the latter of the years.

I found fitting a vacuum gauge really helped me see what was going on. That's obviously a medium term thing rather than immediate short-term.

You could disconnect the fuel line and try sucking diesel through to see what the pipes are like. I don't particularly like the taste of diesel but find fitting the oil extraction pump to the fuel line is a good way to try to clear it. You'll soon feel if it is clogged or the diesel runs freely.

If it does run freely and the filters are clean (new filters are cheap if you buy equivalents rather than Yanmar's own brand) then next idea would be to check for some form of air leak. If you bleed the system does air seem to get back in?

If not that then it could be something more complex like a lift pump on its way out.
 
I bet a virtual pint it's crud in your fuel filter. Doesn't matter how recently it was changed: if you've a decent bit of bug or other crud washed down from the tank it can clog a new filter. Enough fuel can get through to start, but not enough to continue running except possibly at tickover or maintain low load.

If it were just gradual accumulation of muck in the filter the engine would have progressively lost power over a long period of time.

When you change the filter, make sure you've got a further spare one on board. If you've got a significant dose of the bug or lot of dirt in the tank, you may find the same or simlar thing happening again next time the tank is stirred a bit. With a further spare you'll be able to get home next time. (Note you may also be able to get home by motoring only slowly). If it keeps happenning the tank needs cleaning out.
 
There's a possibility your fuel system may have a small filter/screen on the pick up pipe in the fuel tank, which can get clogged if there's any muck or bug in the deisel. Certainly worth a look see before changing the primary or secondary filters..
 
Make sure you have clean fuel in the tank ..................... the fuel gauge maybe showing that you have but ..
The tank sender (float) type systems have been known to fail (especially VDO ones); and if they go open circuit they will always show full!! Mine failed a few weeks ago but was showing 3/4 and actually moving the gauge a bit and it fooled me into thinking there was plenty of fuel ..... there wasn't!! At the start of the problem, the engine would run at tick over but would stall when I tried to increase revs.

Take off the pipe that runs from the tank to the primary filter (if fitted) at the filter end, and try to suck diesel through; if there is no fuel you will get a mouth full of air!! If the pick-up is blocked then you will "feel" resistance and little fuel will come through; if there is fuel then you will get a mouth full of nice clean diesel!!!!
Don't trust the gauge, check somehow that you really do have fuel in the tank!!!!! [experience :( ]
Good luck,
Alan.
 
When I had a similar problem I rigged up a clean fuel feed from a jerrycan and tapped it in first at the secondary filter(newly changed)and the engine ran fine.I moved the feed back to the primary filter and it still ran fine so I narrowed down the problem to the feed from the tank.Sure enough I found crud blocking the pipe from the bottom of the tank,and more crud sitting in the tank.The whole thing was drained and flushed,treated with biocide and all was well.Ill do it again soon to ensure no repeats.
 
Had a similar problem years ago.
Turned out we'd run out of fuel.
Ooops!
Literally the last thing I checked.

Seriously, these things run for ever if undisturbed. Has anything changed? How many hours has it done since the fuel filter was changed? Never ceases to amaze me how long a bit of air takes to work through. Is the agglomerator/filter letting air in? That's a common problem.
 
Its done about no more than 20 hours since the filter was changed and it was all declared "very clean". Unfortunately its looking unlikely that an Engineer can get out before the weekend. So my plan is;

1) Check there is fuel (99% confident it's at least 2/3 full, but will check anyway :-)
2) Try running at idle for a longer period, without increasing RPM, and then in gear at tickover
3) Check the breather is clear (this should be fairly easy to do, with good access)
4) Change the secondary filter and bleed (about the limit of my competence!) and see what state the filter is in

For those that have mentioned cleaning / flushing the tank, does this have to be done by removal of the tank or are there flush agents you can fill up and then drain off whilst in situ (BTW the tank does not have a drain on it)

Thanks

Matt
 
So I couldn't remove the secondary filter and couldn't bleed air from it either, no fuel would come through. Enclosed picture shows the condition of the primary CAV filter. I guess this is the dreaded "bug"?

Could it be as simple as changing all filters and dosing with Marine16 or GrotaMar 71??

Also, what do I need to do about the Eberspacher (not that it has been run from months)
 

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