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Old 10 September 2012, 11:59   #1
Country: UK - England
Town: Surrey
Boat name: Fugly & Rokraider 1
Make: Pac 22 & Porter 6.5
Length: 6m +
Engine: Ford 250 & jet,DT140
Join Date: Jun 2008
Posts: 681
Smokey Ford Sabre 250

I have got a Ford Sabre 250 in my Pac 22. I know they have a reputation for being smokey on start up and improving when they warm up. However I am not satisfied with the amount of unburnt diesel being spewed out the exhaust. I am constantly travelling in a diesel smog that is both unpleasant and probably very unhealthy to be around. I have had the injectors checked and a couple of them needed a slight tweak, but nothing that would sort this out.
The engine was supposedly reconditioned about 400 hours ago so I assume that the basics are in good shape, so the next step is the pump. The engine was a non turbo engine standard. As far as I can make out, all Sabre did was stick a good sized turbo on it and crank the pump up to give it extra fuel for the turbo to make the power. The pump is a very basic inline unit and has no boost capsule, so it just chucks fuel in depending on where the throttle lever is set. problem is that increasing the fuel at the top end to make use of the turbo also increases the fuel at the bottom end of the spectrum which I believe is contributing to the smoke problem. So my plan is to build the pump with a boost capsule that will allow adjustment at the bottom end, so at idle, the fuel being delivered will be the same as the non turbo engine, and as the boost comes up, it will open the rack up and increase the fuelling to match the turbo at the top end. This should give a nice smooth power delivery and hopefully clean it up across the power range. Has anyone on here done anything similar and how did you get on?

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Old 10 September 2012, 12:30   #2
mister p's Avatar
Country: UK - England
Length: 4m +
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I haven't done this, so I don't know if it would work.
Does that help?

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Old 10 September 2012, 12:56   #3
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Country: UK - Channel Islands
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Make: Osprey Vipermax
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Smoking engines like this are either over fuelling or lack of air supply.
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Old 10 September 2012, 13:25   #4
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Originally Posted by Erin View Post
Smoking engines like this are either over fuelling or lack of air supply.
Correct but there is nothing wrong, its just the turbo doesn't do much until 1800 revs which is were the over fueling takes place. Once past 1800 revs the air fuel mix is restored by the turbo and it burns clean.

These are very old engines now, I would just use and enjoy it.

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Old 11 September 2012, 10:04   #5
Country: UK - Scotland
Town: glasgow
Boat name: arriba
Make: marlin
Length: 7m +
Engine: suzuki 300
Join Date: Jun 2007
Posts: 303
had a couple on a ranger 36 diesel smoke died down at 2000 revs but it ate oil we could only leave marina very early morning
Once went thru crinan canal neary killed everyone in the locks
there after always went round mull we fitted a engine water heater 240v that seemed to help at start up as engine was warm
never miss an opportunity
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Old 11 September 2012, 12:34   #6
Country: UK - England
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What colour is the smoke, is it black?
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Old 11 September 2012, 12:55   #7
Country: UK - England
Town: Surrey
Boat name: Fugly & Rokraider 1
Make: Pac 22 & Porter 6.5
Length: 6m +
Engine: Ford 250 & jet,DT140
Join Date: Jun 2008
Posts: 681
The smoke is grey mostly when cold at idle. When the revs are increased the smoke output increases with them. Once it is under load, it does clean up some,. When the power is increased if not done gently, it will chuck out a large black cloud initially but will then clean up some.
My thoughts are that the pump has been cranked up to make the power at the top end, but by doing so the fuelling at the lower end has also been increased and the engine can't physically burn it all until the turbo kicks in.

I am hoping the pump modification (boost capsule / smoke box) will allow it to run with the correct amount of fuel off boost as it would have been in its natural non turbo spec and will richen up as the boost increases. This hopefully will clean it up some, it is unacceptable as it was.
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Old 11 September 2012, 14:44   #8
Country: UK - England
Town: Southampton
Boat name: Searider / War Shot
Make: Avon / Scorpion
Length: 4m +
Engine: 30hp Yam / 150hp opt
Join Date: Sep 2003
Posts: 1,846
If it is a factory Sabre 250 it should already have the boost / fuelling gear.

212c certainly does.

The smoke may simply be due to the low compression needed to run the high boost to make top end power.
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Old 11 September 2012, 17:32   #9
Country: UK - N Ireland
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Some thoughts!

Check the pump timming if its to late (retarded) you will have un-burnt fuel which is white, you could try to advance the timming and see if this helps.(mark the position of pump as it curently is and then slacken bolts and use a leaver to twist the pump round a little, do this with the engine running and you will hear the revs pick up if you are advancing the timming, or if slowing down you are going the wrong way) Not to much or it will run warm and mabe even Knock a little.

Another possibility is oil leaking past the valve stem oil seals (sitting overnight or for longer periods) and then on start up it is smokey until it burns this excess oil off. Worn valve guides is also a common fault but thats another discussion.

As mentioned compression could be down however, if it starts without to much trouble this is unlikely.
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Old 12 September 2012, 03:33   #10
Country: UK - Wales
Town: Here
Boat name: doggypaddle
Make: Avon 5.4 Searider
Length: 5m +
Engine: yamaha 80
Join Date: Jul 2007
Posts: 1,107
could also be dribbly injectors.(poorly atomised fuel will not burn and condenses on the piston crown, vaporising as the engine warms making white smoke) I would whip them out and get them tested first. If it was to do with overfueling because of the turbo/pump settings the smoke would be black, and then only with the hammer down and lugging to get up boost. Its may be a combination of things, stem seals, dribbly injectors, etc.
start with injectors and pump timing. then check turbo seals.
stem seals can be replaced without removing the head with a little inginuity.

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