Could anybody help me with the following please, engine gets to 5200Rpm at WOT then drops to 3500- 4000 Rpm and surges around 200Rpm at this rev range.
Picked it up from the repairer yesterday fitted with two new fuel pumps, mechanic also fitted an auxilary tank post engine filter (Approx 50mm hose to the tee piece that feeds both pumps (Indicates no obstruction or air leakage). While water testing the front carb shroud was removed and six healthy sprays to the carbs at >5000 rpm then the sprays decayed consequently rpm drops. Carby's have been stripped and cleaned.
Mechanic removed fuel pump from crankcase while at idle and commented on low crankcase pressure and that this may not be enough to operate the diaphragm sufficiently at high demand. Is now suggesting problem may be crankcase sealing rings between 4 & 6 as these are the two cylinders that operate the diaphram pumps (Not sure on the cylinder #'s).
Welcome thoughts comments
Picked it up from the repairer yesterday fitted with two new fuel pumps, mechanic also fitted an auxilary tank post engine filter (Approx 50mm hose to the tee piece that feeds both pumps (Indicates no obstruction or air leakage). While water testing the front carb shroud was removed and six healthy sprays to the carbs at >5000 rpm then the sprays decayed consequently rpm drops. Carby's have been stripped and cleaned.
Mechanic removed fuel pump from crankcase while at idle and commented on low crankcase pressure and that this may not be enough to operate the diaphragm sufficiently at high demand. Is now suggesting problem may be crankcase sealing rings between 4 & 6 as these are the two cylinders that operate the diaphram pumps (Not sure on the cylinder #'s).
Welcome thoughts comments