My 1997 Mariner 150 EFI is having an 'occasional' issue in which, sometimes, when I give it throttle from a standstill, the RPM's only go from idle to about 3000 RPM's no matter how hard I push the throttle. It's like it's only getting fed half the gas it should! Then, after 3-4 seconds, the engine "kicks in" and takes off to the level of throttle that I expect, becoming fully responsive with no delay. More rarely, when this condition occurs, it will take upwards of 15-20 seconds for the engine to respond to my accelerating.
When this happens, I've tried pumping the throttle (I had a Hotplate installed a couple years ago). I've also tried stopping and restarting (always fires up instantly to a nice healthy sputter-free idle), but this doesn't help. It's not a 'warm' vs 'cold' engine issue either---have seen it happen under both scenarios.
The motor otherwise runs beautifully. Once I'm humming along after it 'kicks in' it never reverts to this 'half the gas' situation at all... it's very smooth, no issues once it's kicked in. This is all about initially accelerating to get on plane from an idle or very slow state.
And this doesn't happen all the time. Perhaps only 10-20% of the time!
Any clue to what's going on? I've done some searching and the only thing I've seen that might make sense is the TPS (Throttle Positioning Sensor)? What else could it be? The boat is serviced annually (every year)---I've had it for about 3 years now, and it has a clean bill of healthand runs great overall. Ah boats/motors---it's always somethin! Thanks for any feedback.
When this happens, I've tried pumping the throttle (I had a Hotplate installed a couple years ago). I've also tried stopping and restarting (always fires up instantly to a nice healthy sputter-free idle), but this doesn't help. It's not a 'warm' vs 'cold' engine issue either---have seen it happen under both scenarios.
The motor otherwise runs beautifully. Once I'm humming along after it 'kicks in' it never reverts to this 'half the gas' situation at all... it's very smooth, no issues once it's kicked in. This is all about initially accelerating to get on plane from an idle or very slow state.
And this doesn't happen all the time. Perhaps only 10-20% of the time!
Any clue to what's going on? I've done some searching and the only thing I've seen that might make sense is the TPS (Throttle Positioning Sensor)? What else could it be? The boat is serviced annually (every year)---I've had it for about 3 years now, and it has a clean bill of healthand runs great overall. Ah boats/motors---it's always somethin! Thanks for any feedback.