Fouled spark plugs and running rich I think

Hello

Way back in September I was planning a ride to colorado.
I did the 8000 mile inspection stuff then caught a bugger of a cold a week before leaving.
A relative offered me a free ticket to fly instead and not feeling up to full strength I  went for it.

The Friday I would have left on the bike for trip it would not start. The couple days before that it started a bit rough.

The next day I flew out and had a grand time visiting daughter and grandson.

Just now sitting still to deal with the no start issue.

I pulled the plugs and they were black and sooty.



Installed new plugs and bike started up.

Don't think it was really fixed just the clean plugs letting it start better.

Today I finally got air filter installed and the old one does not look that bad.
I pulled the plugs and they look a bit dirty but not bad.
I cleaned them up and going to see how it reacts.

Is there any airflow sensor or something that could be causing it to run rich?

Any help appreciated.

Mike <><

gizmoguy wrote:

Hello

Way back in September I was planning a ride to colorado.
I did the 8000 mile inspection stuff then caught a bugger of a cold a week before leaving.
...... I pulled the plugs and they were black and sooty.

Installed new plugs and bike started up.

Don't think it was really fixed just the clean plugs letting it start better.

Today I finally got air filter installed and the old one does not look that bad.
I pulled the plugs and they look a bit dirty but not bad.
I cleaned them up and going to see how it reacts.

Is there any airflow sensor or something that could be causing it to run rich? Any help appreciated.

Mike <><

I moved from the SW coast of Florida, which is about 3ft elevation to Boulder Colorado at around 5300ft. This was a huge big change for the '02 SWing I had at the time. Due to the huge air density difference it starting running really rich. I cured the issue by installing iridium tip plugs, KN filter / de-snorkled the air box, and disconnected the battery to 'encourage' the ecu/fi to reset. I also had a TGB 150 delivery scooter and had to rejet it as well (carburetor engine).

More air in and efficient plugs worked so well I now install iridium plugs, hi flow air filters and mod the airbox in all my vehicles. They also idle smoother, accelerate better and get better MPG.

I had spent about 6 years in West Oregon and know the air is very moist and dense -- generally good for performance, and very unlike here, so you may have a sensor/ecu issue going on, but I thought I would offer some tips on what has worked for me.

The Swing relies on a MAP (manifold absolute pressure) sensor to precisely administer the correct amount of fuel to the available air. In conjunction with an ambient temp sensor and engine coolant sensor among even more sensors, the Swing engine automatically compensates for altitude. You can put in all the Iridium plugs and K&N air filters and drill your air box all you want, but I'll wager that your problem lies with a faulty fuel pressure regulator. This is a common problem for older Swings that have also sat for a long period of time.
Your diagnosis of the rich running and fouled plugs is typical. To be sure, remove the under seat cover to access the throttle bodies, and remove both vacuum hoses running to the intake manifold from the T connection of rubber hoses. If there is any sign of gasoline in either of those hoses, you've found your problem. It's easy to replace the fuel pressure regulator despite what the service manual says about removing the intake manifold. It's not necessary. Do a search here on fuel pressure regulator if you don't have a service manual.

You might also want to read this that I had posted about correct fuel regulator part #'s:

https://www.silverwing600.com/t6741-fuel-pressure-regulator-assembly-tips-and-part-s

big bird wrote:

……. I'll wager that your problem lies with a faulty fuel pressure regulator. This is a common problem for older Swings that have also sat for a long period of time.

This makes sense in this case for sure. My current Swing is an '04 and runs perfectly, but I will certainly keep this in mind. Likely I will replace these parts as a precautionary measure sometime over the winter when I get to the engine for other checks. Good info.