Intermittent FI trouble light activation

[Fritzer]

Purchased a mint condition 1999 with 36,500 mi on it last year with a strange intermittent FI trouble light activation issue.  It may go for days without coming on then it will go thru a phase where it comes on often and most often without any noticeable trouble in engine performance.  There is no fault code noted at start with kickstand down.  

 

However, when riding a month or so ago I noticed while reducing the throttle, rather that a smooth linear deceleration, I got a small abrupt drop off that was slightly noticeable.  I looked at the light and it seems that event set the trouble light off.  Since then, if I notice that abrupt increase in deceleration it will usually come with the trouble light on.

 

It makes me think that it is a throttle position sensor connection or bad ground issue.  I unplugged/plugged the main connector to the tps unit under the tank  and that did not solve the problem.

 

Does anyone know where I should start looking?

 

 

[Aimbot9000]

If its randomly flashing like a ABS or traction control light does its most likely a bad ground  if its flashing a repeating code you have a problem.  To look up stored codes  you jump the black 2pin plug on the wiring harness on the left hand side under the seat near the R/R. 

Steps are in the service manual 

I had a short that caused my fi light to come on or off randomly and when I'd break, traced that back to a bad connection in the orange ground bus that is in the section of the wire harness in front of the r/r. 

Oh and welcome to the site

[Fritzer]

Hi Aimbot,  

Thanks for your response.

The light does not flash.  I comes on and stays on until the bike is turned off.  On restart, light is off.  

Wire harness in front of the r/r is referring to rectifier/regulator as opposed to right radiator?

Thanks for the digital shop manual.

This is a great site for VFR owners.  I am very happy to be a part of it.

 

 

[Fritzer]

I opened up the two connectors in front of the rectifier, noted on the schematic that the two green wires are ground on the four prong.  Everything looked and felt solid but noticed that some type of paste had been used in the connectors.  This must be some type of di electric grease that inhibits corrosion?  Does anyone know what type to use since I don't see anything in the manual about it and I have never used this stuff before.

 

After I put it back together and run it, I will let the thread have the results.

 

 

[Terry]

The grease you have found is dielectric grease, popular among VFR owners to stave off connector corrosion. 

[Fritzer]

Thanks for the grease tip Terry.  I will pick some up.

 

After cleaning the rectifier connection I was looking at the wiring schematic and noticed that a lot of the wires from the rectifier and the TPS went to the ECM.  While I had the seat off, I removed the connectors to the ECM, cleaned them up a bit, then put them back on.  Finished installing cowling and got it ready to give it the test ride.

 

Last time rode it 2 days ago, the light was coming on within 2 miles of riding.  Today did a 15 mile stint (would have rode longer but raining) and the light did not show itself.  So far so good.  Seems like the above described procedure is possible solution for others with similar symptoms.  

 

If the intermittent warning light issue returns, I will update.

 

Thanks for the help