Sudden dramatic decrease in fuel efficacy?

[Johnson]

I filled up my 05 FZ6 with standard gas (lowest) from the same station I've always used and went to work and back (30 miles each way, mostly freeway) and today on the way in I've noticed I am down to maybe a quarter of a tank or less! My memory is a bit foggy since I've started to regularly commute again but I swore I got more mileage than this. I want to say I would get at least 3 round trips before needing to fill up?

No apparently leaks that I've noticed or anything strange for that matter. Tire pressure is fine, chain slack is fine. Spark plugs recently replaced. Any ideas?

 

[Gary in NJ]

When you last filled it, did it take a volume that made sense? In other words, if you ride for 100 miles did it take 2-1/2 gallons?

Also, have you confirmed that your fuel gauge isn't off? Fill the tank and confirm the volume.

 

[TownsendsFJR1300]

It's rare I run my down that low but when it does read that low and I top off, I find the tank doesn't take much fuel(IE, there's more in the tank than the gauge shows).

I'd simply top it off, re-set the odometer and do your trips.

*When re-filling, record the actual mileage covered and the gallons used. Divide and figure out MPGs.

You should (stock engine, no PC), be seeing anywhere from 42-50 MPG...

 

[VEGASRIDER]

Spark plugs recently replaced. Any ideas?

what kind of plugs? Iridium? I knew of a member with an 04 or 05 and the bike did not accept those plugs kindly in terms of fuel efficiency. On the other hand, I've had zero issues with Iridiums, got over 50k miles on them.

 

[TownsendsFJR1300]

what kind of plugs? Iridium? I knew of a member with an 04 or 05 and the bike did not accept those plugs kindly in terms of fuel efficiency. On the other hand, I've had zero issues with Iridiums, got over 50k miles on them.

The first set of Iridium's I put in mine (I don't remember how many miles but less than 10k), I pulled them and found the gap had opened up beyond spec since I installed them (WEAR!). Maybe .002" but they shouldn't have worn that much, that soon.

Next change, I'm going back to stockers. When I replaced those at around 12k, they were in really good shape, within spec's too. I changed them just because of the mileage (no issues).

I didn't find any difference in mileage or how the engine ran between the different plugs. Actually, I remember the idle dropped slightly with the iridium's installed (which I though was odd, but easily "fixed")