'08 WRR let me down - bad low-fuel light/sender?

Hey gang, it's been a while.

For the first time ever, my titular (I just like that word) commuter didn't fire right up today. Cranked along, but no hint of a kick. Quick troubleshooting: turned off/on kill switch, sidestand, etc. (shouldn't even be turning over if that), checked for gas in tank. The trip mileage was high-ish, but the fuel light wasn't on. Fuel pump was priming when I'd turn on the key. Nothing and the battery was getting low. For fun, I put about a gallon of gas in from the lawnmower supply (not the right octane, but I'll deal with that later) and after letting the fuel pump prime a few more times, it finally fired up.

I didn't trust it enough to ride to work, so I brought the truck, but it's looking like it was a classic no-gas situation. Even though there was some gas. And the fuel light wasn't on. But we all know how reliable those can be.

Thinking back, the last time I'd filled up was right before taking my kid for a ride last weekend. We didn't flog the bike, but it was more load than usual. So that might account for running low a bit sooner than usual (usually hit the light around 90 miles and I was at 75). I'd also started the bike for a new neighbor kid (4 year old already has a 50cc dirt bike w/ training wheels!) and let him rev it a few times. So . . . eh?

Hoping it sparks right up this evening.

Now, about that fuel light . . . . anyone else had theirs go out? Usually mine come on too early, not too late. Is there a test for the sensor/sending unit?

Thx for any pointers. Bad enough to not have a reserve, but to no even have a functioning low light then relies too heavily on my telepathy.

The fuel pump primes until the desired pressure is reached (takes 2-3 seconds), or times out if there is no fuel to draw (takes much longer); so how long did the pump prime?

The check for the fuel sensor is on page 8-78 of the service manual.

johnkol wrote:

The check for the fuel sensor is on page 8-78 of the service manual.

Thanks for the pointer - totally blanked on checking the FSM.

Last night, I rode it to the gas station and topped up with nearly a gallon of gas. Guessing what I put in that morning, was about right for it to have been a low-fuel situation. Put on a total of 15 miles last night with a few shutdowns and starts with now problem.  Rode it to work today (~50 miles r.t.), again, no problems.

As for how long the pump had run initially, I can't say. We were getting our carpets cleaned and that guy's van was running right in my ear and I already had my earplugs in (no helmet yet). I did move away from the van when I was trouble shooting and at that point, the run time was the typical 2-3 seconds, but I honestly can't say if that was only AFTER I put fuel in.

I should have time to pull the tank and test it this weekend.

I have (only) 11k miles on the O.G. '08 fuel pump. I didn't seem to be one of those cursed with the bad batch, as this is the first problem I've had. Might be time to order one though, and keep the original as a spare.

Pulled the tank today. Tipping it to the side, the sender resistance was right in the middle of where it should be. Back level (half full) it read as an open circuit. Drained the tank to near empty, put it back on the bike and after running about 5-10 seconds, the fuel light finally came on. Refilled the tank and it went out.

So seems to be working now. Not sure if I had to knock it loose or something. Or if the problem the other day was not fuel level. When I drained the tank, I did get some crowd out of there, so maybe something got temporarily blocked up.

We'll see how it behaves going forward.

Welp, it tried to let me down again after work today (I've ridden about 150 miles since the last problem). Started up, then died right out. Fuel pump was either not running at all, or running weakly for about a half second when I'd turn the ignition on. Eventually got a good prime after sloshing the tank around, hitting it a few times, and also removing the fuel cap. Fired up and made it the 25 miles home without issue. Tested it two more times this evening and it ran fine.

But I'm ordering a new fuel pump. Anybody got a favorite vendor for price/speed balance?

Found the master thread about dead fuel pumps. Ordered the Kemso pump.hopefully good for another 14 years.

Oblivion wrote:

Started up, then died right out. Fuel pump was either not running at all, or running weakly for about a half second when I'd turn the ignition on.

If the bike started, even for a second, this means that the pump primed enough to have reached the correct pressure.

You mentioned you were at work. Was the bike sitting in the sun, and how hot was it? Usually pump problems manifest themselves on very hot days with very low fuel in the tank.

Yeah, was sitting in the sun, about 85F ambient and about 65 miles on the tank (about the same level as the initial problem).

I meant that it initially started right up (did not notice pump whirr) but it died after a few seconds. On subsequent cycling of the key, the pump either did not run at all, or for a fraction of a second, weakly, then stopped. Engine would crank but no fire. I then, key off, leaned the bike way over to the right and back and also opened the tank to visually check fuel. After closing the cap and waiting about 30 seconds, I finally got a good 3-second prime and ignition. Wondering if opening the tank let hot air out???

And then this morning I remembered that last year on a hot day, stuck at a train, the bike had died on me. I chalked it up to overheating, though the fan never ran. I even tested the fan after I eventually restarted and got home. But thinking back, that was likely a hot fuel pump as well. The "wait, and it eventually works" cycle was very similar. The only thing that does not fit the profile is the time it didn't start in the morning a couple weeks ago when I started this thread. It had been in the garage, in the morning, not yet above probably mid-70s.

So, I dunno. What I do know is I'm changing out the pump and crossing my fingers.

From what you describe, this latest incident does sound like a fuel pump problem. Given that you have already ordered the Kemso, let us know how it goes after you install it.

I received it yesterday and got it assembled last night, but I've decided my 14-year-old o-ring should be replaced, so it'll be a few days before I slap it back together. Will advise.

I finally got the new O-ring yesterday and got everything back together. She started right up. I almost expected her not to because the new pump is so much quieter than the old one. FYI, I went with the KEMSO-13001 via Amazon. I think $40 these days.

We’ll see how it goes in the long run.

Hopefully you noticed that the power leads have tabs that lock onto the Kemso leads, and they did lock when you inserted them. I didn't pay close attention to mine when I installed the Kemso, and the tab had been damaged somehow; a couple of years later the lead came off and I got stranded in the middle of nowhere. Don't let that happen to you.

I did see that mentioned in a post, probably yours, and did give them a light to moderate tug test both last week when I assembled it (had to adjust one tab) and again Thursday before I installed. Thanks for the warning, for sure.