bukh trouble

chewi

chewi

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I have a BUkh DV10ME that starts ok with no throttle, ticks over, runs OK at power for hours. When I slow down to moor it fails to tick over and will not restart for some time,maybe 30 mins or so
if I fail to moor first time I am in trouble!

fuel is clean, no water in the bowl. gravity fed (with lift pump as well)
tank has plenty left.
Any ideas?
 
That’s odd. If it was cold then the compression would be a question mark but if it’s warm....
Is the airflow ok? Is the HP pump OK? Is the injector OK? Any leaks in the fuel feed when its warm?
I appreciate that all these things can only be checked by refurbishing stuff but check all the union nuts from the HP to the injector and the injector itself, if a nut has worked loose that would perhaps do it. Is the air filter OK?
 
The "fails to tick over" part is not clear to me. Doesn't the starter kick in at all, or engages, but isn't able to turn the engine?
 
Have you checked the fuel filters?

When I had my dose of the bug I had the same symptoms but could restart straight away. Opened the primary filter and found a jelly substance covering about three quarters of the filter. My conclusion was a normal speeds the engine could draw enough fuel at low speed it could not.

Picking up the mooring or coming along side was a two person job one on the throttle the other on the tiller.
 
Thankyou guys, Another new filter then, that can do no harm.

Any idea why this only happens after a long run/hot but not when cold?
 
Probably "hot" and "cold" are not the keywords. They would be a "long rest" and "short rest". During a longish power run the dirt particles in the filter get "compacted" causing the filter having a high resistance. The low pump pressure after reducing the revs will cause fuel starvation and the engine dies. During the rest period the particles get gradually "uncompacted" and at some point the engine will start again - ready to repeat the cycle.
 
I had a similar problem yearsago on bukh 10, diagnosed as a sticky fuel rack not freeing after a 'stop' when hot. It would only restart with a very fast turnover. I even bump started it a few times with sail assist, even spinaker combined with starter. prevention was best taking time to go back to tickover before stopping, never stop with gear engaged.(which I did to lock the shaft when sailing)
 
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I had a very similar problem on my DV20. Would run fine for hours, but as soon as I decreased the revs, the engine would die and wouldnt restart. The puzzling part was that after an hour or so it would start again after it had cooled down enough. It turned out to be a faulty injector. I had the nozzle replaced and it worked fine. It is really easy to take the injector to a diesel specialist to have checked, which only costs around £5.

If your fuel filters are clean, I would check the injector next.
 
new engine filter fitted. There was some cystallised brown stuff in there. , but not in the water trap/primary which is odd.

swapped the injector with one of another engine which I had tested on the way to the boat so I know it's good.
btw Thankyou to Poole Diesel who tested it instantly at no charge.
he didn't think the injector could be the cause, but fitting a known good one is not an issue.

His diagnosis was a possibly partially blocked return pipe building a backpressure that is overcome by the lift pump at power, but not at hot tick-over, so the engine stops till the pressure eases.

I blew through it till I heard bubbles in the tank, but I think I will increase the diameter this winter. as it was harder than I expected.
At least if thats the cause I can relieve the pressure after failure and it should restart.

I can only know if its fixed when I make a longish run again.
 
That's what everyone said to me along with many professionals. I spent a long time diagnosing the problem. That's why it was so baffling. No one thought it could be the injector until that was the last thing I checked. Have the the old one checked for the spray pattern I bet it just squirts in one stream rather than atomising the fuel.
 
It would indeed be ironic if it is the injector, as I spent University time studying petrol injectors, particularly charging the fuel stream to 25KV to improve atomisation...

H&S were not convinced by our anti-explosion defences.
 
stevd said:
Did the replacement injector solve the problem?
Click to expand...

I don't know yet, I haven't undertaken a significant stretch to give me that confidence.
It has since occurred to me that since I have seen crud in both the filters in the last season, that there may be some still in the lift pump, which is the lowest point, and likely to collect there, so I will clean that out before I try a longer run..
I already blasted the rest of the pipes and the tank during the winter, but I didn't think to dismantle/clean the lift pump.
 
If you get the old injector tested and it is found to be faulty, you will know that you have found the problem and should give you the confidence to use it.
 
stevd said:
Did the replacement injector solve the problem?
Click to expand...

In short, no it did not.


I motored about 2 hrs from hengistbury head to Lymington , and the engine was OK at Lymington..
I motorsailed from Lymington to upperhamble, about 3 hours, and the engine quit as I approached the pontoon, biut it restarted and I drove into the pontoon OK..
There was more water this time, so I replaced the prefilter.

I sailed back to lymington, and used the engine just the last hour
Engine was OK on arrival, but still had water in the prefilter.

then sailed back to Poole, used the engine from Heng,head for about 3hrs, and it quit again on approaching the mooring. 30 seconds or so later it restarted.

It does seem to drop revs substantilaly below tickover when throttled down, sometimes it recovers, sometimes not.

Despite cleaning the tank out in winter I have a serious water problem, but I don't know why.

Nor do I understand the dying to sub-tickover.
tickover is set at 1000rpm


-(
 
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