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AuthorMessage
NB_Gema
NB_Gema

Posted: Tue Jun 27, 2017 9:31pm

Post Subject: Slow pick-up and hunting

Dear experts, we have a Barrus Shanks 35 engine. When the boat has not been used for a while, it starts OK. But after a few days running, when starting in the morning it is very difficult to get it to pick up revs, and even when it does if I then return the throttle to anything like tick-over, it runs at less than normal tick-over. So the revs are difficult to control until it warms up after about 5 minutes. In addition, having not started it more then every few weeks this year, it has started hunting at any revs when cold or warmed up - the revs increasing by about 100 rpm and then dropping back every few seconds. I know that Barrus's do not sell these engines any more and others have had problems with them. Do you have any suggestions of diagnoses or solutions? I did ask an RCR engineer about the cold running problem a year or two ago when he came about something else, but he had no idea what was causing it. Thanks Alan Diamond

Tony-B
Tony-B

Posted: Tue Jun 27, 2017 10:03pm

Post Subject: Slow pick-up and hunting

I believe this engine was sourced in Korea and marinised as a cheaper model by Barrus. The fact they have stopped ding them says, think, a lot. I have not even been able to find any photos of them on Google so can not be sure about their equipment. I suspect it has a Korean made injection system that may well not be to the standards we expect today. It is probably a simple four element in-line injector pump with a centrifugal governor. What you call hunting is actually surging when a diesel does it and it often indicates the governor keeps on "overshooting" the correct position so it revs up, dies back, and revs up again. Some pumps have a fine adjustment to damp this at idle but I doubt yours does so I suspect a sticky control rod/rack for some reason. However that may only partially explain the other symptoms. All the symptoms suggest a fuel problem to me so what state are the filters in - have you had one apart to see what it may have caught. Not only the main engine filter but also any pre-filter between the tank & engine plus any strainers that may be in the lift pump. Do you more or less fully open the throttle as you try to start it? This would help force a sticky control rod to the starting position but throttle back as soon as it fires. What colour smoke comes from the exhaust while t is cranking but not yet started? A few wisps of typically white smoke or no smoke at all indicates a lack of fuel. Do you regularly drain/suck whatever has collected in the bottom of the tank to minimise water build up and check for early signs of bug? I do mine once a year in the spring using an oil extractor down the filler. It would not hurt to phone Barrus to see what they have to say about it. At this stage I can not recommend that you have the injector pump overhauled but certainly change/clean all the filters and water traps on the fuel system and send me a photo of what is inside them. If you can point me to a proper workshop manual for the engine including details of the injection equipment I will see if there are any adjustments you an try.

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