More on my low revs problem

Jobs_a_ good_ un

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it all started after I had the engine service and shaft replacements to my water pumps
Prior to this work the last time I had been out on the boat I sailed from Chichester to lymington at 3600 rpm both engines went like a dream
Next time out port engine was only pulling at 3400 rpm
So call to dave crawford engineer yanmar main dealer he sarted saying there was a plastic bag around props or some thing tangled says this could have happened in the marina as last time we went out it was fine(chichester trip) so I looked underneath with underwater camera nothing there not a dickie bird tiny little bit of weed under boat.
next thing he tried was taking off the fuel filters and found a load of sludge in filter says theres bug in the tank filter was duly cleaned and bug cleaner put in tank still low revs
Next trick was to sea trial boat and clean all fuel lines out remove and blast out fuel pipes still low revs
next trick was to run boat from a 5litre jerry can to chack there was enough fuel getting through still low revs
He says the next step is to service all the injectors big cost no boat for 2 weeks
Engines are yanmar 250s on shafts
What does the panel think is this the next step ? /forums/images/graemlins/frown.gif /forums/images/graemlins/frown.gif /forums/images/graemlins/frown.gif
 

bdsweeting

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How is the exhaust ?

Any shortage of air getting into the engine ?

Has the maximum throttle position been moved at all ? Is the throttle fully open?
 

omega2

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This is now becoming a saga, please start from beginning, 1 were they ok before the engineer "looked at them". 2. Was the muck found during his inspection. or after he had left. What is the colour of your exhaust or better still the Transom i.e. any black sooty deposits. IMHO I would suggest that there is an air leak in the run between the turbo and the inlet manifold, check all clips on the air intake side. As far the fuel side is concerned did the filters get fitted properly i.e. are they seated, are there any signs of fuel leaking on them, and last of all are these engines managed by computers or manumatic? the former is a authorised dealer job and the latter is a spanner mans. Good luck I know how annoying it can be, but in the end you are going to have to get your hands dirty.
 

omega2

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Another thought, are the water pumps driven off the timing case? ala Sabre's and Mermaids, if so could the FITTER have moved the distributer pump pully during the operation and upset the timing.
 

Lakesailor

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[ QUOTE ]
The throttle pushes all the way down but wont go past 3400 on its own

[/ QUOTE ]
You mean at the throttle handle? Is that being transfered to the throttle on the engine. Does the throttle lever on the pump move all the way or has the cable slipped?
 

Porthandbuoy

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[ QUOTE ]
How is the exhaust ?

[/ QUOTE ]

I don't know if you have solid or flexible exhaust hose. If flexible, consider this.
Exhaust hose can look okay externally but may have partially collapsed internally. It happened to me with a Yanmar 1GM10 which worked fine at low rpm, but just wouldn't deliver max rpm even under no load conditions.
 

Jobs_a_ good_ un

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Revs were fine before the service was done we drove for about 2 hours at 3600 rpm
The muck in the filter was found after the service when he went back to inspect why the revs were low all he changed for the service was the elements on the bottom of the filter
The exhaust comes out under water so any soot would go strait into the sea but there dont appear to be anyblack sooty bits about
dave crawford is the yanmar main dealer for lymington so I presume he fitted the filters properly
Im trying not to get stroppy with him but we havnt eactly got off on a good footing
As for the air leak between manifold etc I don t know
 
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