low power/sputter/when throttleing from idle

[beckarae]

I have an issue that when I advance throttle there is a bogg and sputter with very low power. if i back off the throttle and hit it hard again it may or may not take off as usual. sometimes I need to start from no throttle a few times before a smoth transition in rpm can happen. Once I get threw this rough spot engine runs great under load, also idles fine. It is only the transition to get on plane.I have cleaned my vst filter, and checked fuel pressure both at idle and under a load (when engine is bogging. 35 to 38 pounds. I have also cleand and tested the 0/2 sensor. fuel filters and lines are all new and un restricted. I have not done a vacume check (not sure how) however I am under the impression if the fuel pressure can maintain 35 pounds then it seems fuel starvation can be ruled out. I am a bit suspect of the throttle possition sensor. Can someone direct me to a tps test so I can rull that out.
It is tuna time here in northern Ca, I have missed two good runs already and i sure would like some tips.
Engine model. S250TXRW salt water series 250 hp 2 stroke fuel injected (not high pressure injection)

[boats.net]

Should have 5 volts plus or minus .25 volts between orange and red wire of TPS with key on, Synchronize throttle plates and before resetting idle screw set TPS at .5-.52 volts between pink and orange wire with throttle plates completely shut, should be able to see voltage slowly increase as throttle is opened up.
May need injectors cleaned.

[beckarae]

Thanks. I will try to test TPS and report back.

[rodbolt17]

for the injector filters.
look up a mercruiser 7.4 MPI in the 1998 -2000 range.

[beckarae]

rodbolt17 can you please elaborate. I assume you are saying that the little filter that is pressed in the top of the injector can interchange with a mercury 7.4? And mabey you can help me understand the reasoning behind cleaning injectors for a flat spot in throttle tip in? (idles perfect runs perfect just when applying throttle from say 800 - 2000 rpm there is a spot where there is no power with alot of sputter) I very much value any input, but it does help if i can understand therory. I own a automotive repair shop and though I am not at all familiar with 2 stroke outboards I am familiar with injector, tps, and 0/2 sensor opperation. I am not at all questioning your advice I just am not understanding.

[rodbolt17]

your system uses CCS,
thats Controled Combustion System.
it shuts down the spark on #5 between about 600 to 800 RPM.
between about 800 to about 1800 it shuts down 2 and 5.
its very particular for the correct TPS setting,O2 sensor feed back and the spark plug cap resistance.
yes the green injector filters can be replaced for about 3 dollars each with the mercruiser part.
the TPS and plug caps can be tested on land.
the O2 sensor feed back MUST be tested with the lower unit submerged.

[beckarae]

Just finished testing throttle possition sensor, results as follows. voltage between orange and red wire key on 0. voltage between orange and pink at closed throttle .62 smooth sweep up to 4.15 full throttle. I switched out with a known good TPS adjusted and retested, results as follows. set with throttle closed at .51 smooth sweep to 4.1 volts. I am a bit confused to the function and test results of first test between orange and red wires. is this even possibe to have no voltage in this test and then have a voltage sweep between pink and orange. I wont know until I put it back in the water if anything changes. I really appreciate all your input!!!!!!!!!!!!!!!!!!!

[rodbolt17]

you did something wrong.
on the wiring harness, orange to black you should read 5 v.
any orange wire under the hood has this 5V reference.
pink to black is the pick off voltage.
the test harness adapter shifts the color codes.
why I dunno.

[beckarae]

I agree I did something wrong as far as orange wire. However when I put the spare tps in I did test the orange again and it did have the 5v refrence and .51 to 4.1 sweep (checked with lab scope) and sweep is clean, no drop out or glitches. I have since put it in water for a test run, results as follows. once warmed up idle is at 600 rpm slow roll in the throttle still bogs and hesitates until it reaches 2700 rpm then in an instant it will jump up to 3800 rpms. 2700 rpms every time, like that is the spot to transition from low power to running perfect. from there i can back off the throttle down to 1000 rpms and roll in the throttle and it dosen't seem to have that breaking point from bad to good at 2700 rpms. when rolling into the throttle it dosent matter if I smash the throttle or roll in gradually. always 2700 rpms is the spot where it gets better. I now am more curious about the operation of the CCS system (controled cumbustion system) what exactly turns off and on #2 and #5 Is it possible that I am only running on 4 cylinders until 2700 rpms and then ???????????????? how could I test this. Your input is great!! If you were here I'd buy you a few thats for sure!!

[beckarae]

By the way, I ran the engine test with cowling off and a fuel gadge hooked up. never did the fuel pressure drop below 35 psi ran mostly between 37 and 38 psi.

[rodbolt17]

you can check it by monitoring CDI output voltage.
did you ever test the plug caps?

[beckarae]

What is CDI and what should the voltage be. (location and wire color) Test plug caps ??? sorry to be a pain but I've come this far, sure would like to see it threw

[rodbolt17]

each plug cap has a resistor.
unscrew the plug cap from the wire and test with an ohm meter.
4-6 K ohms.
cdi output is 100V min at cranking and 130 min at 3500.
must be checked with eiter a peak reading meter or a digital with a DVA adapter.
RMS value wont work.

[beckarae]

Still not solved, Had an apointment with yamaha tech, he got the flu and canceled. I at this point am leaning twards the CCS. What signals the ecm to shut down #2 and #5 is it the tps? or a different sensor. I am suspesious it may be a shift position sensor (Idea from my Yamaha tech) who now is sick if so where is this sensor

[beckarae]

Ok. I think I found what I have been looking for. there is a shift cut switch mounted to the shift linkage on the engine, it is a two wire switch with blue and black wires. now to understand proper operation. Is this a normaly open switch (in nutural and closes in gear or visa versa). and will this switch (if bad cause 2 cylinders to drop out??