ISSUE: Running Rich, over-fueling, poor gas mileage

Hey all,

I just recently bought a 6th gen VFR w/ABS. It has higher mileage (approx. 80k) and looked to be pretty well maintained (although no maintenance history). Motorcycling season is just getting underway here in Toronto and I've had a chance to ride it a few times. I've noticed a few issues that I hope you guys can help point me in the right direction:

1) Running rich - I've noticed a gas smell in the exhaust, even after the bike is running at temperature.

2) Horrible gas mileage - I've ridden 94km and have three bars left in the tank. It was initially filled up the the neck. I have done all city riding though.

3) Oil smells of gas - oil definitely has a gas smell. I will have to do an oil change but would love to figure out why gas is getting in there in the first place.

4) feels sluggish - I don't have a baseline (other than the 5th gen I used to have) but it definitely feels sluggish.


Things to do:

I will check my air filter. Bike is getting up to normal operating temperature. Run a can of seafoam to clean injectors. Plugs are expensive!

Any other thoughts?

 

I'd say you might have a leaky injector and/or the fuel pressure regulator is kaput.

The FPR has a rubber diaphragm that can perforate with age and that will allow fuel to leak down into the vacuum line, so pull that off after the bike has been running and see if there is any liquid present in it.

There are professional fuel injector cleaners out there that can clean and calibrate the injectors and give you a health rating for them.

 

It's not giving you any FI codes?

On a modern FI bike the first suspect would be the Oxygen Sensor in the exhaust. If it is malfunctioning, giving the FI ECU inaccurate information that says the exhaust gas it too lean, then the ECU might be over-fueling the engine trying to compensate. This situation could possibly exist without causing an FI trouble code to pop up. I don't have an Owner's Manual for the 2006 so I don't know what the service/replacement interval is on the Oxygen Sensor.

 

Although, the other symptoms you mentioned make it sound like your problem is something else...

Gasoline in the crankcase oil is a seriously bad sign. Something you need to solve.

Makes me wonder if there's a problem with one of your fuel injectors, something causing it to stick open when the bike is running. This condition would result in your engine running on only 3 out of 4 cylinders, which would explain your comment about the engine being "down on power". A cylinder with a "stuck" injector would be too rich to fire when the spark plug goes off. All of this excess fuel would either go out the exhaust header or drain down the cylinder walls into the crankcase oil.

In this scenario that bad injector would be flowing fuel any time the fuel pump was running (providing pressure).

You could run the bike at idle and see if one of the header pipes doesn't come up to the same operating temperature as the other 3 cylinders. I use one of those little infrared gun-type temperature sensors for this sort of testing, but you could do it by touch if necessary.

 

Great information. Thank you all for your feedback.

If it's a faulty fuel pressure regulator, would I be able to smell gas around the airbox area like it was a spill?

I will touch the headers...that's a great suggestion.

There are no FI codes thrown.