Need help! My Drifter 1500 is running all too rich and I can't figure out why.

[Fab]

Update on this issue.

Here is a photo showing the before and after. On the left, a pair of new spark plugs after about 20 miles (before the TPS adjustment); on the right, a set of new spark plugs after 130 miles following the TPS adjustment. Fuel consumption has decreased significantly.

Let me know what you think of the spark plugs on the right side of the photo.

[Fab]

Troll, you're a legend!

It was the TPS - the one thing I hadn't checked.

While the value at WOT was 4.59 V DC (just within the upper limits specified in the service manual), the value at idle was well outside the range. I didn't write it down, but I believe it was around 0.784 V DC or something similar, whereas it should be between 0.584 and 0.604 V DC.

I tried to adjust the TPS settings a first time using a multimeter and ended up with an AFR that was way too lean. Poor acceleration, hesitation at low speed, a lot of afterfiring on deceleration, and spark plugs that looked like bleached after just a few miles.

I quickly realized what I had done wrong: while I was taking measurements with the multimeter, I took a shortcut and connected the ground lead to one of the cylinder head covers. This caused the meter to read a higher voltage than the actual one.

So I checked the voltage again, this time connecting the ground to pin 21 of the ECU, as indicated in the service manual.

After a relatively short ride, it seems the motorcycle is now running smoothly. I then checked the spark plugs, and they appear to be healthy.

THANK YOU! THANK YOU! THANK YOU!

[Troll]

Dumb question, but, since I can't see it, does it have a "tuner" installed? Try running it for a while with the r/s airbox cover off. Let it breath directly without the crossover restriction. Check the TPS voltage as per the service manual. One of the sensors is map, the other is baro. Do not connect a hose to the baro sensor. Have you checked the running fuel pressure? Lastly, does it have the correct ECM installed?

[Fab]

I need help from forum members who have more experience than I do.
Here's a brief description of my problem:

I got myself a 2001 Drifter 1500 about a year ago, ans the bike has always been running all too rich:

- very high fuel consumption. Low mileage between 25-30 mpg (11–13 km/l)
- spark plugs fouled with black soot (dry carbon deposits, not oily) that eventually cause misfires and starting problems
- a smell coming from the exhaust and black smoke when revving

Actions taken so far with no results:

- replaced the fuel pressure regulator with a standard one, since the previous owner had installed an FPR with higher pressure
- replaced the vacuum hoses with new ones
- replaced the air temperature sensor, the coolant temperature sensor, and both MAP sensors
- I tried several injector/system cleaners
- I repeatedly removed and cleaned the spark plugs, only to see them get fouled again shortly afterward
- I replaced the spark plugs with new ones - I also tried hotter spark plugs, with no improvement
- The service shop also had the injectors cleaned and tested by a specialized company, as well as  they checked and cleaned the fuel pump and fuel filter
- The ECU shows no error messages when following the procedure outlined in the maintenance manual and on this forum

I've run out of options.

Does anyone have any ideas about what I could do next?

Thank you!