98 GTX Ltd 951
The engine runs great when first started, but after a few minutes of running intermittently loses power (can't even get on plane).
The problem:
1. Ignition timing is normal (3.60mm BTDC) when cold, but backs up all the way to 0mm BTDC, when it starts running bad.
2. Curiously, the timing problem seems somehow related to throttle movement:
- It first appears after throttle is closed after a high speed run.
- Working the throttle carefully back/forth across mid-throttle seems to sometimes restore proper timing, whereas simply going to WOT guarantees the timing will retard.
3. All of these observations where made with a timing light, with the boat running--in water--while tethered to the dock.
Questions:
1. Are there any known issues with this engine regarding intermittent timing retard?
2. What effect does the engine temp sensor have on ignition timing? Again this problem doesn't occur with a cold engine.
3. The service manual mentions a "hall-effect throttle sensor" installed in the throttle cable and further states that this effects ignition timing. However, I could not find any such sensor on the boat.
4. I hate to go out and buy the expensive ignition control module (which also controls everything else on the boat) if there is a simple explanation.
Thanks,
Steve
The engine runs great when first started, but after a few minutes of running intermittently loses power (can't even get on plane).
The problem:
1. Ignition timing is normal (3.60mm BTDC) when cold, but backs up all the way to 0mm BTDC, when it starts running bad.
2. Curiously, the timing problem seems somehow related to throttle movement:
- It first appears after throttle is closed after a high speed run.
- Working the throttle carefully back/forth across mid-throttle seems to sometimes restore proper timing, whereas simply going to WOT guarantees the timing will retard.
3. All of these observations where made with a timing light, with the boat running--in water--while tethered to the dock.
Questions:
1. Are there any known issues with this engine regarding intermittent timing retard?
2. What effect does the engine temp sensor have on ignition timing? Again this problem doesn't occur with a cold engine.
3. The service manual mentions a "hall-effect throttle sensor" installed in the throttle cable and further states that this effects ignition timing. However, I could not find any such sensor on the boat.
4. I hate to go out and buy the expensive ignition control module (which also controls everything else on the boat) if there is a simple explanation.
Thanks,
Steve
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