recently bought 6 metre boat with dt140 suzuki that sat in a shed for aprox 4 years without being started. have replaced fuel filter, plugs and cleaned fuel pump. when first starting comes up to full power but drops back to about half after about 10 seconds. will remain on full power for a bit longer if primer bulb is continually squeezed. diafram in petrol pump appears ok. Not a problem from fuel tank as we get same results using a fuelcan in front of filter