Intermittent starting of one engine (Throttle valve opening?) 2004 230 SX

[jbusche]

I have a 2004 Yamaha 230 SX

For the last year my right motor only starts intermittently, some days it starts and other days it will not start. Once it starts it runs great, although this last weekend it seemed to idle a bit high. That was after a day of not starting, and after a day of running, on the last morning it did not start but started after an hour or so using theYDS

The boat stays at a location 4 hours from home at the Colorado River, can get very hot some days 120 degrees, where we use it, and I am only able to make it out there on certain weekends so it is hard to work on and test for a long time. Last summer it did not start on a trip, which was a bummer for the kids. So I drug the boat back home to work on it, but when I got home it started right up. So it was hard to find an issue. But when I took it back to the river it would not start the day we got there, but did start the next morning, and ran great for 2 days.

When I say it does not start, it will turn over the starter but it does not kick at all so it seems like spark is off. Last year I tried starter field spray and got no kick.


I have:
Replaced the lanyard switch, and tried with it disconnected, does not help.
Replaced scupper hatch switches, and swapped them, did not help.
YDS says the lanyard switch is OFF both engines when the key is turned on. Which I think is good.
Changed Oil
Changed plugs

After changing oil and doing the plugs, I did notice a little bit of oil on one spot on the air filter, but not a ton, so I sucked some oil out, it was at the F line.

I did not have much time to test things with YDS because we were heading home that day, but I did notice a few things that may be clues.

When I ran a test on the bad engine fuel pump an error came up:
“Engine is running or the throttle is to open, Test again after turning engine off or closing valve”

Throttle Position Sensor - test says - Normal

Throttle valve opening (1-90) was 10.2 deg when the bad engine would not run and 9.2 deg when it decided to run. (will the ECU stop spark and fuel at start if Throttle is to open, >10, ???)

Good engine was Throttle valve opening 1.9 deg, when not running and the same when idling, which seems substantially different from the bad engine.

I am heading out in two weeks and trying to learn as much as possible so I can bring the right tools and parts and have as many ideas on what to check and try.

Assuming 1 - Throttle valve opening is causing starting issue:

1. Does the ECU stop spark and/or fuel when starting if Throttle valve opening is to open?

2. What should the Throttle valve opening be when starting and idling?

3. Is the cable from the Throttle handles the only thing that controls valve opening (I am assuming the Throttle valve openings are the 4 big round butterfly valves.) or does the ECU also control the opening??

4. Can or should I adjust the cable so when throttle handles are neutral the valve is 1.9 deg like the good engine??

5. Could the Throttle Position Sensor be giving a bad reading to the ECU??? Could that tell the engine not to start?

6. Can you adjust the Throttle Position Sensor??

7.. Could ECU be bad? ECU seems to work well with the YDS. Is there a way to tell if the ECU is OK or has issues with the YDS?


Assumption 2 it is not the Throttle valve opening causing the intermittent starting issue.

- What else should I be checking??

- Can a bad temp sensor make the ECU prevent engine from starting? Never had a over heat light in dash but in the YDS it says over heat warning was on a number of times.

Thanks

 

[Cobra Jet Steering LLC]

If the throttle positioning sensor is not showing it is completely closed it will not start but it will turn over. I have had that happen to me numerous times try moving the throttle back and forth a few times and then in neutral see if it starts.

 

[Neutron]

I have a 2004 Yamaha 230 SX

For the last year my right motor only starts intermittently, some days it starts and other days it will not start. Once it starts it runs great, although this last weekend it seemed to idle a bit high. That was after a day of not starting, and after a day of running, on the last morning it did not start but started after an hour or so using theYDS

The boat stays at a location 4 hours from home at the Colorado River, can get very hot some days 120 degrees, where we use it, and I am only able to make it out there on certain weekends so it is hard to work on and test for a long time. Last summer it did not start on a trip, which was a bummer for the kids. So I drug the boat back home to work on it, but when I got home it started right up. So it was hard to find an issue. But when I took it back to the river it would not start the day we got there, but did start the next morning, and ran great for 2 days.

When I say it does not start, it will turn over the starter but it does not kick at all so it seems like spark is off. Last year I tried starter field spray and got no kick.


I have:
Replaced the lanyard switch, and tried with it disconnected, does not help.
Replaced scupper hatch switches, and swapped them, did not help.
YDS says the lanyard switch is OFF both engines when the key is turned on. Which I think is good.
Changed Oil
Changed plugs

After changing oil and doing the plugs, I did notice a little bit of oil on one spot on the air filter, but not a ton, so I sucked some oil out, it was at the F line.

I did not have much time to test things with YDS because we were heading home that day, but I did notice a few things that may be clues.

When I ran a test on the bad engine fuel pump an error came up:
“Engine is running or the throttle is to open, Test again after turning engine off or closing valve”

Throttle Position Sensor - test says - Normal

Throttle valve opening (1-90) was 10.2 deg when the bad engine would not run and 9.2 deg when it decided to run. (will the ECU stop spark and fuel at start if Throttle is to open, >10, ???)

Good engine was Throttle valve opening 1.9 deg, when not running and the same when idling, which seems substantially different from the bad engine.

I am heading out in two weeks and trying to learn as much as possible so I can bring the right tools and parts and have as many ideas on what to check and try.

Assuming 1 - Throttle valve opening is causing starting issue:

1. Does the ECU stop spark and/or fuel when starting if Throttle valve opening is to open?

2. What should the Throttle valve opening be when starting and idling?

3. Is the cable from the Throttle handles the only thing that controls valve opening (I am assuming the Throttle valve openings are the 4 big round butterfly valves.) or does the ECU also control the opening??

4. Can or should I adjust the cable so when throttle handles are neutral the valve is 1.9 deg like the good engine??

5. Could the Throttle Position Sensor be giving a bad reading to the ECU??? Could that tell the engine not to start?

6. Can you adjust the Throttle Position Sensor??

7.. Could ECU be bad? ECU seems to work well with the YDS. Is there a way to tell if the ECU is OK or has issues with the YDS?


Assumption 2 it is not the Throttle valve opening causing the intermittent starting issue.

- What else should I be checking??

- Can a bad temp sensor make the ECU prevent engine from starting? Never had a over heat light in dash but in the YDS it says over heat warning was on a number of times.

Thanks

The tps should be adjustable to a point. And yes is it is showing its open too much it wont start. Do not set your idle with the cables, use the adjustment at the throttle plates. There should be one adjustment screw that sets all of them. You adjust the cable to take out the slack after the throttle plates are set.
The tps could be bad or have a bad spot in it

 

[jbusche]

Great info, encouraging this maybe the root of the intermittent starting. I have a service manual, It show a procedure to sync the different butterfly valves together than all to a setting. Hard to understand, hope it is clearer when I am looking at the engine. It sounds like they are adjusting valves to be fully closed. I can not find specs in the manual. Are valves to be fully closed at start?

The YDS says the TPS test is normal, not sure if it can still have a bad spot.

Heading out in 2 weeks, this is a good start any other insight is greatly appreciated. Thinking what tools and parts to bring, should I bring a new TPS? are they easy to swap between engines.

Is it easy to swap ECUs or it that a big project to get to them?

Thanks

 

[Babin Farms]

Is it easy to swap ECUs or it that a big project to get to them?

Thanks

if the ECU’s are like the 07-09 models it’s a two person job and not the easiest if you've never done it before. I’ve done mine a few times and it’s easier but I’d still prefer to not have to do it again.

 

[Neutron]

Great info, encouraging this maybe the root of the intermittent starting. I have a service manual, It show a procedure to sync the different butterfly valves together than all to a setting. Hard to understand, hope it is clearer when I am looking at the engine. It sounds like they are adjusting valves to be fully closed. I can not find specs in the manual. Are valves to be fully closed at start?

The YDS says the TPS test is normal, not sure if it can still have a bad spot.

Heading out in 2 weeks, this is a good start any other insight is greatly appreciated. Thinking what tools and parts to bring, should I bring a new TPS? are they easy to swap between engines.

Is it easy to swap ECUs or it that a big project to get to them?

Thanks

Dont try to mess with the sinc adjustments, not your issue, yds can still show a good tps when its out of adjustment.
There must be an idle adjustment, which is just one adjustment.
If it idles good when it does run then dont mess with it just hook up yds and see where your good engine is, then hook up the yds to the failing engine and see where it is. If it is showing open then it needs to be adjusted

 

[jbusche]

With the YDS it show good engine 1.9 deg at start and idle, the bad engine is at between 9.2 to 10.2 deg. Yes the goal is to set bad engine to 1.9 without messing with all the sync setting. Just need to figure out how to do that. Hoping it is obvious when I see the engine. Hope it make engin reliable.

What lube or cleaner is best to put on the valves?