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Tan
Tan, MerCruiser Certified Technician
Category: Boat
Satisfied Customers: 10618
Experience:  40 yrs. experience with complete engine repairs both inboard/outboard and MerCruiser Certified Technician.
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I have a 72 evinrude starflite 100 electric shift and

Customer Question

i have a 72 evinrude starflite 100 electric shift and when your on the lake it'll be doing just fine and then wham !!! its like you hit something , and the faster your going the worse it is, its like the eng. loses fire for a second or two and then comes back, and ni have been told that its the shifter clutchdog in the lower unit but i had to replace that when i bought it due to wrong fluid and faulty solenoids and the previous owner had the same problem with it "slamming " the boat, so its hard for me to believe that both lower units had a faulty shifter clutchdog? i believe its in the pulse pack but would like your opinion.
Submitted: 1 year ago.
Category: Boat
Expert:  Tan replied 1 year ago.
Hello. My name is***** only way to determine if this is an ignition issue is with the use of a timing light. Connect the timing light to each spark plug wire. Run the boat watch the timing light flash. The flash should be steady if it steady move to the next cylinder. If you find a misfire you have a bad spark plug wire or a cracked dist cap. If all cylinders misfire then you have a coil or pulse pack issue. If no misfire then the lower unit is the problem. When you replaced the clutch dog did you replace forward gear also. If not this is why the clutch dog has gone out again. The clutch and the for gear have lugs that engage each other so it one is worn so is the other. A new clutch and an old gear won't last long. Thats like putting new break pads on and old scored up rotor. The new pads wear out faster due to the scored rotor. Post back with questions. Post back with questions.
Customer: replied 1 year ago.
i only replaced the whole lower unit with a used one off ebay, thats why i really wonder if both lower units could have the same problem, also it doesn't do it when its out of the water with the muffs on only when its completely in the water.
Expert:  Tan replied 1 year ago.
A lower unit of that age most likely has allot of hours on it so it is very possible it had the same failure as your they are of the same year. The engine will not act the same with no load. On a flush there is no load on the prop so it won't jump out of gear.

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