FI light after extended high speed run

Hi... this one is a bit perplexing to me.

2005 ST1300. Just turned 60k miles. Seems to be in pretty darn good shape, no leaks all runs smooth, starts promptly and idles fine. 3 bars and only 3 bars ont he temperature.

But after some extended high speed runs, say 20 minutes at 90+ mph the FI light comes on solid and stays there until I do an extended shut down (extended being like a minute plus, not a quick on/off).

I can run at 85 (indicated) for an hour and no problem.

But if I run 90~100 for awhile, I get the FI light lit and it stays on until I shut the bike off for a minute. I tried just shutting it off and then restarting while riding (pop the clutch at slow speed) but it returned to on.

Any ideas?

Check the vacuum lines and 5 way tee under the throttle bodies. Just a little obstruction in here can cause this.

Have you asked the ECM what it thinks the problem is?

--Mark

Maybe the fuel filter is clogged enough so you are getting low pressure at higher speeds.

dduelin said:

Check the vacuum lines and 5 way tee under the throttle bodies.

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Did check the tee recently. When I had the airbox off to add the CC two weeks back I pulled the 5-way out and looked at it. Clean as can be. I though about doing the relocating thing but didn't want to pull the throttle bodies to replace all the lines with longer ones. After fighting and trying to get all the vacuum lines back on it I wondered why I did it. But it was one of those things I knew if I didn't check, it would be clogged.

Blrfl said:

Have you asked the ECM

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Not yet, was under the gun last night and didn't have time. At work today and maybe I can sneak out there with a paperclip and check. How long will it store codes? I've put a 150+ miles on the bike since it lit the FI light.

T_C said:

How long will it store codes? I've put a 150+ miles on the bike since it lit the FI light.

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If the FI light blinks or stays on, there are codes stored. I'm not positive, but if a problem clears itself, I think the stored code goes away, too. I'd keep a jumper handy and read the codes out next time this happens.

--Mark

Slow down!

Easy way to see the code next time the FI light comes on is to stop in a parking lot (or anyplace safe to stop for a minute), make sure it's in neutral and put the side stand down (engine still running).
The FI light will begin flashing and repeating the code as long as you want to watch it. No paper clip required, don't even have to remove the seat.

Don B said:

Easy way to see the code next time

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Ohh.. cool.

When the FI light comes on above 90mph, it means Fine Imminent.

I sometimes refer to the FI indicator as the Freakin' Idiot Light, though not in those exact terms

Don B said:

Easy way to see the code next time the FI light comes on is to stop in a parking lot (or anyplace safe to stop for a minute), make sure it's in neutral and put the side stand down (engine still running).
The FI light will begin flashing and repeating the code as long as you want to watch it. No paper clip required, don't even have to remove the seat.

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+1

Then just consult the Genuine Honda Service Manual to decipher how many blinks means what...

T_C said:

Did check the tee recently. When I had the airbox off to add the CC two weeks back I pulled the 5-way out and looked at it.

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Oops... that might be your problem. The cruise control added a draw on the vacuum system whether it is operating or not. Always just a certain amount of vacuum loss. Normall the engine has plenty and can overcome, but I won't be surprised to find that at the large throttle angles necessary to support continuous 90+mph runs the MAP sensor is reading lower vacuum than the mixture map expects. If you can confirm the code concerns the Manifold Absolute Pressure sensor, I would not worry about it.

I have the Audiovox vacuum operated cruise control on my ST1300. No issues, but I have never run sustained speeds over 90mph. Briefly yes. Sustained no.

I don't have a vacuum tank on mine. If you didn't install a vacuum tank that might cure the issue. I have one that could be donated to the cause for the price of shipping if you'd like to try. I bought it for my installation but never installed it because it works fine already.

CarSalesman said:

Oops... that might be your problem. The cruise control added a draw on the vacuum system

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Thanks for the full explanation and offer of the vacuum tank Don... but I added a Rostra CC with the electric motor. So it might be a vacuum leak causing the issue, but not from the cruise.

Plus at those speeds I don't use the cruise, keep the hand on the throttle for subtle changes needed.

I'll be heading for FerryStoc later this week. Considering runing the bike in 4th on the highway for awhile just to see if it is repeatable issue based on sustained high RPM. It'll cost me some gas but maybe a part of the engine is marginal and finding it now will prevent me from being stranded later.

And the answer is??

Don't know... all of my long runs have been at more reasonable speeds since I was pulling a trailer.

I did have it up to 100+ a few weeks back for a few minutes and didn't get an FI light. I did feel some weave starting around 110 (true, not indicated)... and backed off of it. I had the top-box on and it was a windy day.