loss of power

baz1033 · November 7, 2010

Hi

On a recent sea trip to Southwold in a bit of a swell, my port engine started to lose power and as we carried on it slowly got worse.

Once we were safely in port, we changed the engine filters and cleaned the pre filters as we had no new pre filters on board.

The engine filters did have some debris in them, (engine filters are 2 microns and pre filters are 10 microns) however prior to this trip when I had some work done on the boat, I had the port side pre filter replaced as it had a slight leek on the racor water seperator gasket.

I don't know if they just took the old filter out and put a new one in without cleaning it out or draining it off, and this may have caused the problem at sea.

The return trip the next day went well for about 20 mins, but then we started losing power again and this time after 10 mins the engine cut out. Once in Lowestoft I took the filter lid off and noticed that the fuel was half way down the filter so I tried to bleed the system up again got it running but not very well.

I am going to the boat to have a look at it this week and wonder if anyone has any ideas

The diesel is a nice bright red in the tank and it 3/4 full.

cheers Barry

Antares_9 · November 7, 2010

If the primary bowl was not completely full it may be that there is a partial blockage between it and the tank after the tank has been shaken up, this may never present itself at low revs, there also may be an air leak in the primary dragging air in, possibly a combination of both. Try blowing back through the fuel line with compressed air and make sure the gaskets and unions are all sealed fully. That's probably the simplest place to start before looking for more complex (and expensive) issues like lift pumps et all. One final thought, if you have seperate tanks then it is worth checking the vent on the one that supplies that motor.

senator · November 7, 2010

Is it possible that crap in the bottom of the tank is causing an intermittent blockage of the pick up pipe?

We had a weird sort of diesel bug in one tank at work, can only describe it as looking like a flower petal that resulted in two vehicles suffering from problems in gauze filters in the fuel pump rather than the normal filters.

baz1033 · November 7, 2010

It may be diesel bug but I think that turns the diesel a darker colour

Antares_9 · November 7, 2010

Not really Baz, it is not distributed evenly throughout the tank, mainly near the bottom.

senator · November 7, 2010

the only time I have seen diesel bug before it has been like a stringy black gunge but this was like perfectly formed petals and so we were told this is a type of bug too.

pks1702 · November 7, 2010

This thread from another place shows Diesel Bug quite nicely.

http://www.ybw.com/forums/showthread.php?t=196555

It does not sound as if you have this Baz.

senator · November 7, 2010

That is the stuff I had seen before Perry but the stuff we had was totally clean around and just like a formed petal, it did break up and go stringy on touch but was not slimy

pks1702 · November 8, 2010

I am with a check of the seal on the Racor Primary.

I had a Separ Primary that was a real pain to get a good seal based on the design and had an occasion where air ingress did what you describe Baz eventually causing the engine to stop. Fortunately this was just running in the marina.

I changed to a Racor style but can imagine if the seal is not good this could be a cause.

I think as David has alluded I would try checking the simple things first before digging deeper.

baz1033 · November 8, 2010

I am with a check of the seal on the Racor Primary.

I had a Separ Primary that was a real pain to get a good seal based on the design and had an occasion where air ingress did what you describe Baz eventually causing the engine to stop. Fortunately this was just running in the marina.

I changed to a Racor style but can imagine if the seal is not good this could be a cause.

I think as David has alluded I would try checking the simple things first before digging deeper.

I am down to look at it tommorrow and I too think its an air issue, as the lift pump when I hand prime it pulls the diesel up easily so I would say the diafram is fine in the lift pump. the seal on top of the racor fuel seperator is quite hard which could maybe letting enough air in to cause the problem. But with my luck it will be the most exspensive option as always :cry