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**rodbolt17** · 03-24-2015, 07:31 AM

did you TEST the O2 sensor output voltage???
did you TEST the TPS 5V reference?

**oldschool71** · 03-24-2015, 08:35 AM

Could you please explain to me how to do the 5V TPS test. I have not had a chance to test the O2 sensor voltage. I am awaiting new gaskets for the O2 sensor as I just cleaned it all out and want to make sure everything is new before reassembling it. I am just not sure why I am getting a steady 1V from the TPS even if I take the two screws loose and move it, it does not change. I think that I am doing everything correctly as far as the testing goes for this voltage.

**oldschool71** · 03-24-2015, 08:58 AM

I found one of your old write ups on testing the TPS voltage. I will do it as soon as I get home this afternoon. I am wondering if I should just replace the O2 sensor as this motor is new to me and I am worried that it has never been replaced before. I just do not want to put all new gaskets in and then find out I have a bad O2 sensor. In your professional opinion would a bad O2 sensor cause the rpms to fluctuate erattically when I get up to 2000 rpms with no load on the boat?

**99yam40** · 03-24-2015, 06:03 PM

Just what do you mean by no load on boat?

**oldschool71** · 03-25-2015, 08:42 AM

By no load I am referring to running the boat on the muffs in my drive way. I verified the 5V on the orange lead. I set the TPS to .5V and once the linkage was reconnected and I put the idle screw back to its original position I got .6V. When I first connected I was getting .7V with everything disconnected and the butterflies closed. I am hoping that this is what was giving me the surging or the fact that the O2 sensor block was packed full of carbon. I am still waiting on my gaskets and o-rings to arrive so I can put the O2 sensor back on and fire it up to check everything out again. I have gone through this thing and replaced the VST filter, all of the LP pumps, water separator filter, added ring free to the fuel. I think that was it. I am just trying to make sure that I have everything covered. Nothing worse than finally getting on the water and finding out you have more problems.

**99yam40** · 03-25-2015, 09:17 AM

Running a outboard motor with no load at high RPMs is not recommended, but I am not sure if this motor will try to protect itself under those conditions, but some motors might

**oldschool71** · 03-25-2015, 09:50 PM

I am aware of not running the motor to high rpms while on the muffs. I am only running it up to 2000 rpms. The issue seems to happen if I bring it up to those rpms. I am hoping that the o2 sensor is not the problem. I know the tps was off so I am hoping that was part of the issue. I think I have done everything else that I can do but I am open to any other suggestions. I am also going to change the spark plugs to the BR8HS10s.

**oldschool71** · 03-31-2015, 08:23 AM

I put the boat in the water yesterday afternoon and the surging is not there so I think that problem has been taken care of. I am concerned with how much it is smoking. Could the smoking be from the ring free that I added to the fuel? It was more smoke than my old 89 175 XP would have. I made sure that the oiler linkage is adjusted so that it is just off of the pin at idle and at wot the arm is making the full movement. Can this be a sign that the O2 sensor is bad??? I will hopefully be able to at least put the motor on the muffs on Friday and try it again and see what the voltage is at the O2 sensor.

**TownsendsFJR1300** · 03-31-2015, 05:35 PM

Generally, Ring Free will not make your engine smoke excessivly.

However, IF it was carboned up a bunch it may very well be loosening up carbon, etc and blowing it out. A good hard run will help blow excessive crap out of the top end..

I run it in all my gas powered engines, generally much stronger than suggusted with NO smoke..

**rodbolt17** · 04-01-2015, 06:36 AM

give up on the O2 sensor.
think man think.
how could an O2 sensor make an engine smoke?
answer that question and we can continure.

be aware that on any 3.1L engine that had the block replaced since mid year 2003 you cant use the gaskets from 2003 and prior, I don't care what the parts man says.

there is a tech bulliten on it.

**oldschool71** · 04-01-2015, 08:59 AM

I am sorry that I keep bringing up the o2 sensor but it was my understanding that when they go bad they cause the engine to run rich. I am only a novice at this and I am just trying to make sure I have everything covered for a more enjoyable summer. I appreciate everyone's help and advise.

**rodbolt17** · 04-01-2015, 06:45 PM

now we have to define gone bad.
is it telling the ECU its rich or lean???

if unplugged it defaults to rich at low speed and lean above 4000 RPM.

**oldschool71** · 04-06-2015, 10:08 AM

I took the boat out on Saturday and ran it. This was the first time that I have been able to take it out and open it up wide open. The motor starts right up and idles but it really seems to smoke a lot when it is first started and every time it is started after that it always gives off a big cloud of smoke. It seemed to run really great and got on plane very fast. I was able to run the motor up to 5500 rpms pretty easily so I am guessing I will be working on proper propping in the very near future. I am going to go through and measure gap in the oiler linkage to the stop pin to make sure that I do not have that gap to large. Would having the gap in that too large make the motor smoke a lot when started each time??? Rodbolt I believe that you were right to say forget about the O2 sensor and from my understanding I wouldn't have been able to get up to 5500 rpms if it was not working properly so now I think I will just concentrate on the smoke cloud that I have each time I start the motor unless you guys think that it is normal in which case I will leave it alone. Thanks again for all of the replies.

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