Volvo D2-55 gremlins

[dunedin]

After 7 seasons of faultless running (except when a battery switched failed), our D2-55 is having a bad start to the season, to the extent that curtailing safe use.

Having run sweetly for 3 -4 day sails, it suddenly started losing revs punching into smallish waves. This appears to have been caused by diesel bug in the tank (though the filters were still clean, when draining the tank there was gunge at the bottom which possibly clogged the inlet pipe?).

However, having thought that was the issue and cleaning the tank (as much as was possible without dismantling the entire boat), we are now having further problems, some of which at least seem to be electrical.
Suddenly we have found that, intermittently, sometimes pressing the stop button fails to stop the engine. Pressing repeatedly sometimes gets there eventually. One time I needed to use the manual stop lever (which stopped it immediately).
Equally sometimes it doesn’t power on when pressing the power button (no digits in the small rev counter display, no pre-heat buzzer). Eventually switching the battery switches off and on again allowed to get started (then later failed to stop, as mentioned above).

And having cleaned the tank, and run happily for 3-4 times, today when restarting when the wind failed, the engine started fine but then the revs dropped after a couple of minutes and the engine stalled completely. Couldn’t restart as no lights in the panel.

Any ideas, without a lot of expense changing wrong components. The big issue is it is intermittent, so works whenever an engineer shows his face ;-). Then dies when we try to go sailing :-(

1). Is there any way an electrical fault (start panel, MDi etc) would make the engine stall when running, as opposed to fail to start in the first place?

2). If the the panel buttons are not working (ie not switching on, not responding to stop button), could this be a panel fault (though not just one of the buttons), an MDI fault or something else?

Any ideas appreciated

 

[dunedin]

No bites on a Volvo Penta Engine thread ? The PBO types must be busy.

 

[Bobc]

Not start/stopping is MDI unit failure. Very common.

Lack of power is probably blocked exhaust elbow. Also very common.

 

[dunedin]

Not start/stopping is MDI unit failure. Very common.

Lack of power is probably blocked exhaust elbow. Also very common.

Thanks, yes sound like the intermittent lights not coming on and not stopping could be MDI issue. Just wish could be sure before investing a lot of cash for the second time.

Blocked exhaust elbow less likely. Most of the time no issue with power - can punch along at 8 knots for a while. But occasionally when going moderately the power the revs dropped, and in one case stopped entirely. That does sound more fuel related, unless MDI fault could trigger the stop solenoid.

 

[Bobc]

Thanks, yes sound like the intermittent lights not coming on and not stopping could be MDI issue. Just wish could be sure before investing a lot of cash for the second time.

Blocked exhaust elbow less likely. Most of the time no issue with power - can punch along at 8 knots for a while. But occasionally when going moderately the power the revs dropped, and in one case stopped entirely. That does sound more fuel related, unless MDI fault could trigger the stop solenoid.

Yes, that sounds like you probably have some air being sucked into the fuel system somewhere. Check also the fuel shutoff cock if your boat has one. On Bavarias these are known to get bits of crap in them and restrict the flow of fuel.

In fact your symptoms do sound like a partial blockage somewhere creating a vacuum.

 

[scottie]

Check bad earth connection perhaps

 

[[70521]]

No bites on a Volvo Penta Engine thread ? The PBO types must be busy.

But it is not an engine problem, sounds like fuel and an electrical systems issues.

Can you get a compressed airline to the fuel system? If so blow it through as far as the primary fuel system and see if there is anything blocking the line.

 

[dunedin]

Thanks all. As noted above we definitely have 2 separate issues simultaneously (actually 3, as after sailing back due to engine problems, had a rig problem preventing rehoisting main - happy days!).

The fuel one was (hopefully not still is) diesel bug related - blocking the inlet pipe. Also on second failure definitely got an electric issue.

To aid pinpointing the specific remaining problem(s), does anybody know the answers to these specifics ......

1). Is there any way an electrical fault (start panel, MDi etc) would make the engine stall when running, as opposed to fail to start in the first place?

2). If the the panel buttons are not working (ie not switching on, not responding to stop button), could this be an EVC/panel fault (though not just one of the buttons), an MDI fault or something else?