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Buell Forum » 1125R Superbike Board » Archive through June 14, 2012 » LFL doesn't come on. « Previous Next »

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Mikethebike72
Posted on Tuesday, May 29, 2012 - 08:18 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

My gas mileage is all over the place so a couple of weeks ago, when I got to 170 miles without the LFL coming on, I didn't think much about it. I started kicking myself when it sputtered in the left lane of our 4 lane beltline. On the next tank, I didn't see the light come on and when I went to fill up, I put in 5.1 gallons. I have done a couple of different searches on the board, but most have to deal with the LFL light coming on when cold. Does anyone have info about the LFL not coming on? Any troubleshooting steps for me to take?
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Sparky
Posted on Tuesday, May 29, 2012 - 11:51 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

09R, same problem. Ran out of gas 3 different times when LFL would not come on.

Took it to the dealer who says Instrument Cluster needs to be replaced. Be that as it may, when I did some initial troubleshooting according to the manual, the results indicated "Replace fuel pump". There's probably more that I could have done at home to try to identify what is failing, but since the bike is warranteed for a couple more years, I chose to let the dealer have at it.

Zac4mac on this forum has some pretty extensive troubleshooting steps to follow that should help you find out what is wrong.
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Timebandit
Posted on Tuesday, May 29, 2012 - 03:12 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

The 6.1 version of the IC software looks like it has a logic flag reversed in the truth table that causes the LFL lights to come on inappropriately when CT is cold, and the CEL light to come on inappropriately when CT is cold and tank full / topped off.

The good news is that that software bug doesn't cause the lights NOT to come on appropriately; this means that the software bug is not the cause of your problem. This suggests that you should be looking at the sending unit rather than the receiving unit.

It's been mentioned that drift in the value of the thermistor in the fuel pump may cause the LFL to illuminate inappropriately. I guess it's possible that it may fail in a way that causes it to fail to illuminate the LFL lamp at all.

It's important to remember that the fuel pump is cooled by fuel in the tank, and that a rise in the sensor temperature is what causes the LFL to come on. There are other vehicles that are known to have fuel pump and fuel level sending unit failures if they are habitually run on low levels of fuel, because the pump is not adequately cooled -- Chevy Suburbans and Ford pickups with dual tanks being prime examples. People who habitually run the tank down to less than 1/4 full on the Chevy, or intentionally run the tank dry on their dual-tank F-150 before switching tanks end up replacing fuel pumps. DAMHIK.

This has always made me wonder if the guys who have the fuel temp sensor drift problems are people who run their tanks from full to dry/near dry before refueling. Knowing that this bike has a tendency to heat the fuel, I try to keep the tank topped off whenever I can. I start all rides by going to the gas station, and I try to refuel before the LFL lamp comes on, just to try to avoid heating the sending unit. That could be contributing to it's failure. Just a theory ... not something I can prove.
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Mikethebike72
Posted on Tuesday, May 29, 2012 - 03:25 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Sparky, have you had the IC replaced? Does the light work now?

Time, thanks for the info. I do normally wait until the light comes on since I commute daily on my bike. I am fairly handy with a meter, but don't know what values it should show when full or empty or what wires to check once I get to look at it more.
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Sparky
Posted on Wednesday, May 30, 2012 - 02:18 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Mike, bike is still at the dealer, going on 3 mos, waiting for the IC to clear backorder from the supplier. Hopefully, the dealer will comp my warranty for the time it's been waiting on parts.
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Timebandit
Posted on Wednesday, May 30, 2012 - 01:53 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Sparky, the dealer won't do that for you -- he can't -- but if you call Customer Care at the motor company and ask for a "warranty extension" they will likely extend your 24-month warranty on a parts related issue. I can't say anything about getting a warranty extension on the extended warranty.
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