KevB
Well-Known Member
"I think Gary and I deserve some credit after the hours spent in your bilge!"
What - whilst you watched me change them???
What - whilst you watched me change them???
Engine problem (bit long)
- Thread starter KevB
- Start date
DAKA
Well-Known Member
/forums/images/graemlins/confused.gif
Checked fuel filter drain off ?
Not the same as taking filter off and looking to see if it is half full .
A half fill filter could explain the symptoms.
If that is fine, then check for emulsified water .
Checked fuel filter drain off ?
Not the same as taking filter off and looking to see if it is half full .
A half fill filter could explain the symptoms.
If that is fine, then check for emulsified water .
KevB
Well-Known Member
Hi Matt,
The reason I'm leaning towards fuel starvation is due to the boat zooming off ok with revs 3500 + and 30 odd knots then revs dropping off back to around 2600 in a couple of seconds. Slowing down to tick over for 30 seconds allows the filters to replenish themselves (maybe) Then I can whoosh off until the above happens all over again? Air filters are new but I guess it's easy to try the boat without them.
Any suggestions for a good tank cleaning company? /forums/images/graemlins/frown.gif
The reason I'm leaning towards fuel starvation is due to the boat zooming off ok with revs 3500 + and 30 odd knots then revs dropping off back to around 2600 in a couple of seconds. Slowing down to tick over for 30 seconds allows the filters to replenish themselves (maybe) Then I can whoosh off until the above happens all over again? Air filters are new but I guess it's easy to try the boat without them.
Any suggestions for a good tank cleaning company? /forums/images/graemlins/frown.gif
Andrew_Fanner
Well-Known Member
Fuel pump not delivering enough at higher revs? When the engine isn't working hard, lower revs or unloaded in neutral its OK, but when you need more go juice it wont produce the goods. Hunitng does suggest erratic supply that peters out. Try bleeding between pump and injectors and checking tightness of unions, you may have a bit of air. Don't see why that should affect both engines though. Single fuel tank feeding both engines does very much suggest an issue upstream of the pump.
tcm
...
ah right, forgive me, that's what i didn't see earlier - that the engine revs dropped a lot. Inthat case yep, i agree it's fuel blockage.
LJS and i solved my fuel prob by opening up the the first valve downstream of the fuel tanks and whamming a compressed air line up the thing. Then later i chucked in a load of soltron.
I believe Interlube have a tanker that arrives at dockside, hauls the fuel out, filetrs it and puts it back. It might do this on a recirculating basis. But the cack is usually hard up against the exit line so it might need some recirculation to get it all out.
The compressed air certainly cleared the fuel route although it din't clean the tank - the problem should def go away (for a while) if you could do that first, no?
LJS and i solved my fuel prob by opening up the the first valve downstream of the fuel tanks and whamming a compressed air line up the thing. Then later i chucked in a load of soltron.
I believe Interlube have a tanker that arrives at dockside, hauls the fuel out, filetrs it and puts it back. It might do this on a recirculating basis. But the cack is usually hard up against the exit line so it might need some recirculation to get it all out.
The compressed air certainly cleared the fuel route although it din't clean the tank - the problem should def go away (for a while) if you could do that first, no?
KevB
Well-Known Member
Hi DAKA,
Not sure if you are familiar with the bleed setup on the kad43's? If you are then ignore the following.....
On top of the secondary filter holder there is a nut which you loosen, pump the primer till fuel comes out of the nut the tighten the nut. I assume this is how you tell that the filter is full.
Although when changing the filters the old ones haven't been brimming over with diesel - maybe an inch or so below the top of the filter?
Not sure if you are familiar with the bleed setup on the kad43's? If you are then ignore the following.....
On top of the secondary filter holder there is a nut which you loosen, pump the primer till fuel comes out of the nut the tighten the nut. I assume this is how you tell that the filter is full.
Although when changing the filters the old ones haven't been brimming over with diesel - maybe an inch or so below the top of the filter?
DAKA
Well-Known Member
thanks for comprehensive reply Kev, yes I expected a similar system sorry to concur that is not the problem.
Hunting can be caused by minute cracks in the flexible fuel line letting air in but the chances of both engines going together slim.
Hope you find the problem soon.
another useless thought may not be linked
There is a small pen lid size filter in the engine after the engine filter to guard against filter collapse.
(This is present on older Volvo's 1988, I dont know for sure that new ones have them.)
Hunting can be caused by minute cracks in the flexible fuel line letting air in but the chances of both engines going together slim.
Hope you find the problem soon.
another useless thought may not be linked
There is a small pen lid size filter in the engine after the engine filter to guard against filter collapse.
(This is present on older Volvo's 1988, I dont know for sure that new ones have them.)
Scaramoosh
Well-Known Member
Hi Kev
Do you have EDC controls? If so -
Problem is probably with the starboard engine as revs drop off when turning to starbord, during the turn the starboard prop goes deeper and gets more load while port prop rises and gets cavitation. The fact that revs increase in port hand turn adds confirmation to this fact.
If you have EDC controls the software can be set to get both engines to maintain the same revs for the same throttle position which is why both engines slow down / speed up together. Given it started with rough seas I would suspect that there is a blockage in the fuel line somewhere. Most boatbuilders dont use stainless to save money so you could have a flake of rust stuck in the pipe which cant get through to the filter.
Do you have EDC controls? If so -
Problem is probably with the starboard engine as revs drop off when turning to starbord, during the turn the starboard prop goes deeper and gets more load while port prop rises and gets cavitation. The fact that revs increase in port hand turn adds confirmation to this fact.
If you have EDC controls the software can be set to get both engines to maintain the same revs for the same throttle position which is why both engines slow down / speed up together. Given it started with rough seas I would suspect that there is a blockage in the fuel line somewhere. Most boatbuilders dont use stainless to save money so you could have a flake of rust stuck in the pipe which cant get through to the filter.
DavidJ
Well-Known Member
Hi Kev
I have KAD43's and experienced a not so dissimilar problem which turned out to be the electronic box on top of the engine which switches in the turbo at about 1500RPM.
I'm ignoring the fact that you say it happens on both engines as a drop off in power of one will have the effect of dragging down the other.
The way to test is out of gear freely rev to 1500 and a bit beyond, you should hear the turbo cut in. Same of course for the other engine. Volvo say that it is a very unusual problem yet I had the last box in stock in Sweden at about 200 squid a couple of years back.
My problem was intermittent for 6 months and I could only solve it when the box eventually failed. I swapped the boxes over just to make doubly sure that it was the problem and the fault swapped with it, so it was!!
best of luck
David
I have KAD43's and experienced a not so dissimilar problem which turned out to be the electronic box on top of the engine which switches in the turbo at about 1500RPM.
I'm ignoring the fact that you say it happens on both engines as a drop off in power of one will have the effect of dragging down the other.
The way to test is out of gear freely rev to 1500 and a bit beyond, you should hear the turbo cut in. Same of course for the other engine. Volvo say that it is a very unusual problem yet I had the last box in stock in Sweden at about 200 squid a couple of years back.
My problem was intermittent for 6 months and I could only solve it when the box eventually failed. I swapped the boxes over just to make doubly sure that it was the problem and the fault swapped with it, so it was!!
best of luck
David
Steveu
Active Member
[ QUOTE ]
Although when changing the filters the old ones haven't been brimming over with diesel - maybe an inch or so below the top of the filter?
[/ QUOTE ]
Hmm...doesn't that suggest that air is getting into the fuel supply at or upstream of the fuel filter? you've purged that air at the the nut on top of the filter but air subsequently gets in when the engine runs and that's why the filter bowl isn't full? what do others experience when changing their filters? are the bowls brimming with fuel?....just a thought
Although when changing the filters the old ones haven't been brimming over with diesel - maybe an inch or so below the top of the filter?
[/ QUOTE ]
Hmm...doesn't that suggest that air is getting into the fuel supply at or upstream of the fuel filter? you've purged that air at the the nut on top of the filter but air subsequently gets in when the engine runs and that's why the filter bowl isn't full? what do others experience when changing their filters? are the bowls brimming with fuel?....just a thought
KevB
Well-Known Member
Hi Nick,
I don't have the wizzy edc's, just cable and the tank is plastic so no rust.
I've spoken to Peter's who are going to have a look for me to see if it's something obvious and I'm just being a goon. Probably.....
Kevin
I don't have the wizzy edc's, just cable and the tank is plastic so no rust.
I've spoken to Peter's who are going to have a look for me to see if it's something obvious and I'm just being a goon. Probably.....
Kevin
Vagabond
Well-Known Member
Offer still stands ... 20K cash!
well it needs new engines....!
well it needs new engines....!
omega2
Well-Known Member
I had this same performance with a single engined boat so only one tank and pick up, but what I found could be your trouble, the fuel pick up had been fitted with a fine strainer and this had slowly got blocked with a chalky calcium like substance, I was able to rev freely then it would die, then it would pick up again and then die again, having found the culprit I cut it off, leaving me about 2inches clear of the bottom of the tank. Never had the problem after that.
Vagabond
Well-Known Member
Why don't the fit sumps to fuel tanks so they can be drained?
It's not that hard is it?
It's not that hard is it?
steverow
Well-Known Member
I reckon this is an air supply problem.
Maybe you need bigger vents or bilge blowers.
Try a run out with the engine covers off and see if it still happens.
Steve.
Maybe you need bigger vents or bilge blowers.
Try a run out with the engine covers off and see if it still happens.
Steve.
KevB
Well-Known Member
The air vents are the same size as they have been for the last for years with no problems. (and they are big) Air filters changed recently.
Thanks for all the replies.
You lot have come up with too many possibilities for me to handle so I've put it in the hands of the professionals.
I'll let you know the outcome. And how much......
Thanks for all the replies.
You lot have come up with too many possibilities for me to handle so I've put it in the hands of the professionals.
I'll let you know the outcome. And how much......
compie1
Well-Known Member
Kev,
Run one of the 2 engines on a seperate diesel container, 30 oil drum does the job with WHITE DIESEL /forums/images/graemlins/frown.gif, put feeding and return line init and take of to test, if the engine performs normaly you have found the problem /forums/images/graemlins/cool.gif
This is the cheapest and easyst way of finding your fault but the marine eng. dont like to do that, they cant charge you enough for that!
good luck
Tom VC
Run one of the 2 engines on a seperate diesel container, 30 oil drum does the job with WHITE DIESEL /forums/images/graemlins/frown.gif, put feeding and return line init and take of to test, if the engine performs normaly you have found the problem /forums/images/graemlins/cool.gif
This is the cheapest and easyst way of finding your fault but the marine eng. dont like to do that, they cant charge you enough for that!
good luck
Tom VC
KevB
Well-Known Member
Problem sorted.
Ok, for those who are interested It's fixed. I'm probably going to give someone the opportunity for a lakesailor here but thanks to TCM for his suggestion of whamming high pressure air down the fuel line back towards the tank. This worked. I assume the pickups got gunged up and the air has blown it back into the tank.
So I'm going to give it a good dose of fuel additive and see how it goes. If it happens again I'll know how to clear it and I'll get the tank cleaned.
Thanks to all for suggestions.
Kevin
Ok, for those who are interested It's fixed. I'm probably going to give someone the opportunity for a lakesailor here but thanks to TCM for his suggestion of whamming high pressure air down the fuel line back towards the tank. This worked. I assume the pickups got gunged up and the air has blown it back into the tank.
So I'm going to give it a good dose of fuel additive and see how it goes. If it happens again I'll know how to clear it and I'll get the tank cleaned.
Thanks to all for suggestions.
Kevin
