Motor 2003 175 Johnson V6 carby with 350hrs and separate oil injection.
Problem
1.High fuel consumption. Expected 66 l/hr (17.5 usgph) at wot (5500rpm), get 75 using calibrated Northstar instruments. L/nm = 3.1@2500, 2.1 @4000 & 2.5 @ 5500 RPM.
2.Ragged running between 1200 & 1800 RPM under load or not. Out of the water at 1500 rpm, sounds like it is four stroking, or similar.
3.Difficulty setting revs between 2150 & 2600 under load. Changes from one to other for slightest throttle movement.
4.Oily (sooty?) deposits around motor exhausts and on grass after running for flushing. Oily deposits inside the prop. Collected exhaust water very grey and oily. Oil clings to container sides (ie not on top?). Water smells of fuel. Idling at dock leaves light dry scum on leg at water surface. Oil is Evinrude XD50
5.On flushing, port cylinder heads stabilise at 60deg C (140F) with stbd at 35 deg C at 20 deg C ambient
Other info
Fuel not stale, octane is better than required by spec. No leakage out of carbs or fuel tank. No fuel restrictions. Squeezing the hand pump during flushing gives a firm pump.
No problem starting. Maybe bit rough at idle. Has good acceleration and 31knots at 5400 RPM thru a stainless prop.
Warm engine compression (new uncalibrated tester) at wot is top to bottom 105, 105, 102 (port) 110, 111, 105 (stbd)
All head gaskets replaced recently. No report offered on bore condition but may pursue depending on responses.
Plugs and gaps good but wet with oily deposits when checked. Insulators dark brown
Spark is present on all cylinders at cranking. Strength of spark?( no judgement). No visible differences between plugs in any respect.
Boat is 1600kg (3500Lb) hard top, 21ft glass, moderate v planing with 2.5 ft pod. A previous motor was 140 v4 1.8 lit Johnson circa 88. It pushed the boat well and economically.
Question
Should I be concerned about the perceived problems and are they related.
What action do you suggest.
Problem
1.High fuel consumption. Expected 66 l/hr (17.5 usgph) at wot (5500rpm), get 75 using calibrated Northstar instruments. L/nm = 3.1@2500, 2.1 @4000 & 2.5 @ 5500 RPM.
2.Ragged running between 1200 & 1800 RPM under load or not. Out of the water at 1500 rpm, sounds like it is four stroking, or similar.
3.Difficulty setting revs between 2150 & 2600 under load. Changes from one to other for slightest throttle movement.
4.Oily (sooty?) deposits around motor exhausts and on grass after running for flushing. Oily deposits inside the prop. Collected exhaust water very grey and oily. Oil clings to container sides (ie not on top?). Water smells of fuel. Idling at dock leaves light dry scum on leg at water surface. Oil is Evinrude XD50
5.On flushing, port cylinder heads stabilise at 60deg C (140F) with stbd at 35 deg C at 20 deg C ambient
Other info
Fuel not stale, octane is better than required by spec. No leakage out of carbs or fuel tank. No fuel restrictions. Squeezing the hand pump during flushing gives a firm pump.
No problem starting. Maybe bit rough at idle. Has good acceleration and 31knots at 5400 RPM thru a stainless prop.
Warm engine compression (new uncalibrated tester) at wot is top to bottom 105, 105, 102 (port) 110, 111, 105 (stbd)
All head gaskets replaced recently. No report offered on bore condition but may pursue depending on responses.
Plugs and gaps good but wet with oily deposits when checked. Insulators dark brown
Spark is present on all cylinders at cranking. Strength of spark?( no judgement). No visible differences between plugs in any respect.
Boat is 1600kg (3500Lb) hard top, 21ft glass, moderate v planing with 2.5 ft pod. A previous motor was 140 v4 1.8 lit Johnson circa 88. It pushed the boat well and economically.
Question
Should I be concerned about the perceived problems and are they related.
What action do you suggest.