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Jason, Boat and Mechanical Expert
Category: Boat
Satisfied Customers: 210
Experience:  10 yrs. running and working at my boat dealership.
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1997 Johnson 115 hp missing when advance throttle, idles fine

Resolved Question:

1997 Johnson 115 hp missing when advance throttle, idles fine just starts to studder at higher rpms, plenty fuel in carbs
Submitted: 6 years ago.
Category: Boat
Expert:  Jason replied 6 years ago.
Did the engine sit unused for a period of time before this started happening?
Customer: replied 6 years ago.
no just started acting up around three weeks ago, acted like fuel starvation, discover vro air motor was leaking so changed it, now runs fine up to about 1500 to 2000 rpm the starts missing and stalling,
Expert:  Jason replied 6 years ago.
I am assuming you checked the fuel for evidence of water, trash, etc.? Do you have a timing light? Did you change all of your fuel filters? Do you have a portable fuel tank to use for diagnostics?
Customer: replied 6 years ago.

yes, no and yes I have a portable fuel tank


Expert:  Jason replied 6 years ago.
OK. We can rule out any problems with the on board tank pick up, anti siphon valve, or primer bulb by running it on the portable six gallon tank using a different hose and primer bulb. If you can get your hands on a timing light, then we can rule out an electrical issue. With the cowling off clip the timing light lead to each of the spark plug wires one at a time. Run the engine, and get it to replicate the problem. When it is running poorly, engage the trigger on the timing light. If there is a steady flashing, that cylinder is firing. Repeat on all cylinders. If you do not find any issues with the above, the only other area to spend some attention would be the carbs. Completely disassemble them, soak them overnight immersed in carb cleaner, and reassemble with a factory rebuild kit. I am recommending this since you just put on a new VRO. You could have had some tainted fuel pass into the system causing a restricted passage or a poorly functioning float. Beyond this, you may have received a defective VRO, it happen occasionally. I hope I have answered your question as thoroughly as possible. I would appreciate it very much if you left positive feedback. If you feel you cannot leave positive feedback, please let me know so that I may rectify the problem. Thanks, Jason.
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