Acceleration Problem - Mercury 200 EFI

nitro24

Cadet
Joined
Mar 17, 2010
Messages
7
I recently bought a 1997 Nitro 897 with a Mercury 200 EFI. When I give it throttle, the RPM's only go from idle to about 1500 RPM's no matter how hard I push the throttle. Then normally after 3-4 seconds, the engine "kicks in" and takes off to full throttle becoming fully responsive to speed up or slowing down with no delay. Its just from a stop that this happens.

But sometimes it will take 15-20 seconds for the engine to respond. When this happens, I've pumped the throttle, stopped and re-started, but nothing seems to make any difference in performance.

Any clue to what's going on?
 

Faztbullet

Supreme Mariner
Joined
Mar 2, 2008
Messages
15,616
Re: Acceleration Problem - Mercury 200 EFI

Get you a manual and test/adjust the TPS.
 

nitro24

Cadet
Joined
Mar 17, 2010
Messages
7
Re: Acceleration Problem - Mercury 200 EFI

Am I correct that I'd need a test harness to check it or is there another way? If so, where could I find one?
 

jfordbos

Recruit
Joined
Jul 13, 2009
Messages
3
Re: Acceleration Problem - Mercury 200 EFI

Same issue here, I think... Was this identified for you as a TPS issue? Or was it something else? My story...

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 it 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.
 

CharlieB

Vice Admiral
Joined
Apr 10, 2007
Messages
5,617
Re: Acceleration Problem - Mercury 200 EFI

Start a new thread, this one is over a year old.

Include everything, and what steps you have tried to correct the condition.

Many will not bother to respond to an old high-jacked thread.
 
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