So what do you think caused that then

jac

jac

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Weds evening and motoring back from Cowes. Engine had been running faultlessly, starting easily, fuel new at Easter. Engine running for about 10 mins when someone asked how fast is flat out. Throttle to flat out to find out. After maybe 5 mins the engine lost revs and died. Many puzzled looks in cockpit but engine restarted no problem and then ran perfectly for the rest of the trip at about 2000 rpm.

Gut feel for me says fuel starvation, maybe a partially blocked filter. (Was late so didn't investigate further) Engine is a VP 2040 - any ideas?
 
jac said:
Weds evening and motoring back from Cowes. Engine had been running faultlessly, starting easily, fuel new at Easter. Engine running for about 10 mins when someone asked how fast is flat out. Throttle to flat out to find out. After maybe 5 mins the engine lost revs and died. Many puzzled looks in cockpit but engine restarted no problem and then ran perfectly for the rest of the trip at about 2000 rpm.

Gut feel for me says fuel starvation, maybe a partially blocked filter. (Was late so didn't investigate further) Engine is a VP 2040 - any ideas?
Click to expand...

Five minutes at "flat out" for no good reason? I think the engine has more sense than you!

Mike.
 
It does sound starvation/ blockage related, but hard to diagnose properly as it's now running happily again. As for the reply above, it does a diesel no harm at all to run balls-out under load for a while - arguably the occasional "Italian tune-up" does it some good.
 
Partially blocked fuel breather pipe to the tank? Ok at low/mid revs but when using more fuel a vacume is being created in a tank which the fuel pump after a while can not overcome. I know of at least one boat that had this problem.
 
mjcoon said:
Five minutes at "flat out" for no good reason? I think the engine has more sense than you!
Click to expand...

Small Yanmars are good for up to an hour at their maximum revs. It's good for them to do it from time to time, as long as the engine is nice and warm beforehand from running at moderate revs, and you return to moderate revs to let it cool down gently afterwards. The manual recommends a short run at full speed for every couple of hours at low to moderate cruising revs.

I'm sure small Volvos are similar.

Pete
 
mystique said:
It does sound starvation/ blockage related, but hard to diagnose properly as it's now running happily again. As for the reply above, it does a diesel no harm at all to run balls-out under load for a while - arguably the occasional "Italian tune-up" does it some good.
Click to expand...

I had in mind that running flat out is environmentally unsound because that way you get the least mpg (or km per l) and most CO2.

Mike.
 
mjcoon said:
I had in mind that running flat out is environmentally unsound because that way you get the least mpg (or km per l) and most CO2.

Mike.
Click to expand...

The Italian tuneup is recommended by Yanmar and is practised by many yards, usually at a cost of about £100. It burns off excess carbon on valves and ports and clears out exhaust manifolds. 10 minutes at maximum revs is enough but 20 is often advocated.

Years ago a friend with a Bukh 20 was going on a longish trip and enquired as to the reliability of the engine for several hours' running. He was told that on test they do 56 hours flat out.
 
Some good suggestions there. Hadn't considered blocked breather and think may be most likely. Air filter and fuel filter only have about 20 hours on but the tank is virtually full so doesn't take much fuel to be sucked out to create a vacuum. If tank was 1/2 full would be a different picture.

Will do some investigation over weekend as time with an engine looks more appealing than sailing in a rainy force 8!!
 
vyv_cox said:
The Italian tuneup is recommended by Yanmar and is practised by many yards, usually at a cost of about £100. It burns off excess carbon on valves and ports and clears out exhaust manifolds. 10 minutes at maximum revs is enough but 20 is often advocated.

Years ago a friend with a Bukh 20 was going on a longish trip and enquired as to the reliability of the engine for several hours' running. He was told that on test they do 56 hours flat out.
Click to expand...

That all sounds extremely envirnomentally unsound! But I suppose it might be construed as a "good reason"...

Mike.
 
Might be fuel bug, I have had this, Congregates in the per filter (racor) and restricts the flow. Not enough to stop it but enough to prevent it supplying enough fues for max revs. Because (bad idea I know) our generator take off is after the engine filter I sometimes get the situation that the engine will run perfectly, but the generator with its much smaller pump just does not have enough 'suck' to overcome the restriction.
 
We used to have a customer with one of those big Rover 3.5 Litre cars Like Maggie used to ride in.
He dawdled about the village. Every six months he brought it in for "checking and tuning".

We would give it an Italian Tune-up on the A63 dual carriageway. For the first mile or so clouds of smoke followed us and then cleared.

He used to say "Thank you, it always runs so much better after you've attended to it."
 
jac said:
Weds evening and motoring back from Cowes. Engine had been running faultlessly, starting easily, fuel new at Easter. Engine running for about 10 mins when someone asked how fast is flat out. Throttle to flat out to find out. After maybe 5 mins the engine lost revs and died. Many puzzled looks in cockpit but engine restarted no problem and then ran perfectly for the rest of the trip at about 2000 rpm.

Gut feel for me says fuel starvation, maybe a partially blocked filter. (Was late so didn't investigate further) Engine is a VP 2040 - any ideas?
Click to expand...

My money's on partially blocked fuel filter.
 
It could have been a bit of debris in the tank that got sucked into the fuel line. Once the engine stopped, suction was lost and it fell back into the bottom of the tank.

Worth checking the filter though.
 
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