98 s150txrw. troubles.

[P2]

I have a s150txrw bracket mounted on a 19 foot cuddy. I bought just over a year ago as a used rebuilt . It then started acting up on accelleration out of the hole. I believed this to be fuel related and have rebuilt the carbs and replaced both thermostats and fuel pumps .Everything is set to the yamaha manual spec's for this engine.

I went out on the water saturday and still have the same problem. Idles good and then will run rough on accelleration and load till it reaches a plane. Runs good 3000 t0 3900 rpm and then will run rough again as I aproach 4000. It seems to me that if the motor has a load on it something is failing. Compression is good, spark is good. I believe all fuel related to be good. Timing is as manual states.

I am going back to the manual to read up more but would appreciate any comments or suggestions.

Thanks

 

[P2]

Re: 98 s150txrw. troubles.

I was testing the thermo Sensor and found it open. No continuity at all hot or cold. I will order a new one monday. Can someone tell me if this was or contributing to my problems? I dont know how this interacts with the CD.
Thanks.

 

[99yam40]

Re: 98 s150txrw. troubles.

My 40 has 2 switches 1 tells the CDI the motor is cold or warmed up and the CDI changes timing for cold starts.
#2 tells the CDI the motor is overheated and retards the timing (safe mode) and sets off the alarm
Not sure about yours,but your manual should say something about the system.

My guess is you still have some carb or fuel supply problems.
Here is a good thread for testing supply.
http://forums.iboats.com/showthread.php?t=283363

Did you change the plugs and test the plug caps and coils?

You need a peak reading volt meter or a DVA adapter digital volt meter and a ohm meter to test the pulsar coils, charge coils, and CDI output voltages to compare them to the manual specs..

you need to test things as the problem is happening if nothing shows out of place otherwise. This is not always easy and maybe somewhat dangerous, so be careful if you do it yourself.

 

[P2]

Re: 98 s150txrw. troubles.

Thanks 99Yam40.
This one has two thermoswitches and they check out OK. It also has One thermosensor that is open. Thats the one I dont know what it does.
As for the plugs I changed them when the problem first started showing up. Unfourtunatly its in the salt water alot and its been hard on things. Have installed a new harness also as the original had been repaired a few times and not much left. Tried a set of 200 carbs temporarily and had the same problems.
I will check the fuel system as your suggestion and I will try to run from a portable fuel tank when I get the new thermosensor, but fuel bulb was staying ridgid while running.
Thanks

 

[southern livin]

Re: 98 s150txrw. troubles.

Wish I could help you with this one but I am interested to see what you find as your problem.
I have a 98 s200txrw that has started giving me trouble but has always seemed to run rough at idle. I just rebuilt my carbs, replaced my plugs, and replaced the fuel filters but this did nothing to help. Also my engine is starved for fuel at idle and top end which has just became apparent. I'm going to replace the fuel pumps but i don't think that will solve my rough idle problem which sounds like your issue.

 

[99yam40]

Re: 98 s150txrw. troubles.

I think the open sensor will cause problems but not sure what on that motor. may cause the CDI to do things with the timing being it is carbed and not injected.

Did you do a sink and link on the carbs when you put them back on?

A set of carbs from a 200 may not be the correct thing to try, I do not think they have the same jets , fuel/air ratio. But I have not checked myself.

you can do all the testing in the manual or you can throw parts at it, it is your choice. In my opinion it is better to find the problem and then replace what is broke

 

[P2]

Re: 98 s150txrw. troubles.

Yes to the link and sync. We had the carbs so it was just a try, Everything is stock so we are doing as per manual. Will borrow a peek reading meter this week.
Thanks again.

 

[P2]

Re: 98 s150txrw. troubles.

Just an update.
after all that, I have a very , Very clean and good fuel system Lol. Problem was found in the stator. Charge coil failing. Installed a replacement stator and all is well again. Thanks guys.