Does it ever get full?

[Medic Mike]

Morning everyone:

My question may be simple (I Hope for I am a simpleton). I cannot get my fuel guage to ever show full. I have put in 6.5 gallons before and the guage only registers to one bar just below full. I have had the bike for two years and I have never been able to get the fuel guage to have all bars. I use my trip odometer for when to fill up and only use the guage as guide. This is just a perplexing thing. When I fuel I place the bike on its center stand to fill. I am seeing what the experts have to say. It is not a critical item, just and annoyance and confusing thing.

 

Thank you all

 

Mike

[texasaggie97]

Mike,

 

I am not going to act like I am the pro here but the same thing happened to me one time after I replaced my fuel filter. I had to go back and play with the float till I got it back to where it would measure the fuel correctly. That is how I fixed it but I am sure someone here might know a better way. I just know how you feel it bothered me so that is why I had to figure out how to fix it.

 

Good Luck

[DavidEBSmith]

The float is for the low fuel light. The fuel gauge is controlled by the tube thing in the right half of the tank.

 

Sometimes my fuel gauge goes all the way to the top, sometimes it doesn't, sometimes it goes to the top but drops very quickly thereafter. If there is a pattern to it, it seem like it goes to the top after getting a couple of tanks of non-ethanol gasoline, but it's not consistent enough to be sure.

 

However, it's very consistent at the bottom of the range. One bar it takes 5.5 gallons, no bars it takes over 6 gallons.

 

I have two alternative suggestions:

 

1) Take the tupperware off, take the tank off, take all the connections apart and clean them (a small resistance in a connection can throw off the indication), drain the tank, pull the fuel gauge sensor out of the tank and ensure it's not dented or kinked (vacuum on a tank can cause it to collapse and kink the sensor tube), then carefully reassemble everything.

 

or

 

2) Ignore what the gauge says at the top of the range (you know it's full because you just filled it) and only pay attention when it gets near the bottom.

[Medic Mike]

David:

 

Number 2 is where I am going to sit for now. This was more of a curiosity thing than anything else. Was a tad concerned if it might have been a computer thing/glitch or something more. Thank you

 

Mike

[Alfred02]

Remember that it measures resistance (or voltage drop), so the first and easiest to try first is to get some electrical cleaner, some air-pressure spray in a can and go through every connector involved with the fuel gauge.

Spray each connector thoroughly and let it drip out for a while, then blow it out properly.

A higher then normal resistant connection would easily give you this symptom.

[jfremder]

1) Take the tupperware off, take the tank off, take all the connections apart and clean them (a small resistance in a connection can throw off the indication), drain the tank, pull the fuel gauge sensor out of the tank and ensure it's not dented or kinked (vacuum on a tank can cause it to collapse and kink the sensor tube), then carefully reassemble everything.

 

David's right on the money. Even when everything's perfectly clean, the top bar only shows when things are full to the brim, and then only for a few miles.

[ESokoloff]

 

David's right on the money. Even when everything's perfectly clean, the top bar only shows when things are full to the brim, and then only for a few miles.

 

Yep.

[Mr. Frank]

Mine is the same as Mike's. On very rare occasions I will get all bars for a few miles. OTOH it's accurate at the bottom of the range and the low fuel light is very accurate. Light comes on and 5.5 gallons go in.

[Michaelr11]

David's right on the money. Even when everything's perfectly clean, the top bar only shows when things are full to the brim, and then only for a few miles.

Not always so... I had similar issues on an R1100RT, then when I removed the tank for some brake line work I thoroughly cleaned the tank's electrical connector with an electrical contact cleaner. When I now fill up (on the sidestand) it goes to all of the bars on the guage and it doesn't drop off until I ride 25-35 miles.

[Medic Mike]

Thanks everyone for the advice. Once I get some farkling done, will get this little annoyance fixed. Style before functionality, is that not the Harley Credo?

[Selden]

I just experienced a change in behavior, and I think I have a plausible explanation. I had a solvent mark on the gas cap, and decided to repaint it. I removed the gas cap assembly, and had to wrestle with the part that sits between it and the actual tank. In the process, I replaced the 73 mm O-ring, which had swollen to a point where it was impossible to get the filler assembly to seat properly. Before I replaced the O-ring, I suspect that I bent the sender arm slightly, causing it to push the float lower in the tank. Now full is 10 bars, and about 30 miles later, it reads 9 bars. At the other end, this also means that the low fuel light is likely to come on with 40-50 miles left, rather than 70-80.

[ESokoloff]

I just experienced a change, and I think I have an explanation. ......

I suspect that I bent the sender arm slightly, causing it to push the float lower in the tank.

 

It's my understanding that the arm activates the reserve light(only).

[Selden]

I just experienced a change, and I think I have an explanation. ......

I suspect that I bent the sender arm slightly, causing it to push the float lower in the tank.

 

It's my understanding that the arm activates the reserve light.

Prior to this, no matter how hard I tried, I rarely saw 10 bars, and even then, only for a few miles. I did (intentionally) a similar mod on my old Pacific Coast, which would report a half tank of gas when the tank was still about 2/3 full. Something must be driving the signal to the RID, and I can't think of any explanation other than the angle of the arm to which the float is attached.

[dirtrider]

Afternoon Selden

 

The low fuel light float is WAY down on the fuel pump pass through so it is difficult to understand how you bent that float arm when messing with the fuel cap. This float doesn't effect the RID fuel reading anyhow only the light.

 

The actual float assembly that controls the RID fuel level reading is a long tube with a float inside it so hard to believe you bent anything there.

 

It sounds like you might talking about the rollover valve assembly as that is attached to that part under the fuel fill cap. This has no connection to the fuel gauge or the low fuel light.

 

The only thing that makes sense is that when you were working on it you somehow disturbed a wire connection & decreased it's resistance or somehow improved the grounding.

 

 

[Medic Mike]

Now let me ask this Selden since you mentioned something. I am getting roughly 230MPG on the bike (as far as I know). From what I can tell I am getting 23 miles per bar. I have never pushed my luck with the yellow light beckons. I usually go 20 miles or less and fill. Here is where my confusion begins. I will put 6.5 gallons in and show 9 bars. I will put 6 or 5.5 and get 9 bars. There just does not seem to be a consistent flow in regards to the meter, thus why I use mileage as my fueling tool. I am a novice at 99% of this and not that mechanically inclined. Secondly, I do not have an indoor place to work on it. I am one those rude people that keeps his bike outside 24/7. Since I ride it 90% of my travel, to me it does not matter, but again I am a simple minded paramedic.

[Selden]

D.R. Could the assembly riding a little lower due to a new O-ring explain the difference?

 

Whatever the cause, I'm now getting 10 bars consistently on a full tank. The only way to be certain how far you can go on a tank is to run it almost dry (I say almost because the fuel pump is cooled by being immersed in gasoline). The most I have ever put in, after about 280 miles, was 6.8 gallons. As the saying goes, YMMV.

[skinny_tom (aka boney)]

My friend's RTP was showing 8 bars on a full tank with ignition on, and 5 bars with bike running. We tracked it down to the ground wire for the fuel level sender. For whatever reason, resistance would increase in the ground while the fuel pump was running and result in a lower indicated gas level. We cut the ground wire on the fuel sender side of the 4-pin fuel tank plug and ran a separate exclusive ground to the battery. Problem solved... It goes all the way to 10 and stays there for a reasonable amount of time.

 

Since my RID was only recently indicating 10 bars for about 5 miles after fill up, I did the same thing to my RT the last time I was in there. It now behaves properly as well.

 

Both the fuel pump and the fuel level sender use the same ground. I don't know if corrosion gets in there over time or what, but when separated and connected to a good ground it functions like new.

[Selden]

That explains it, then: disassembly, cleaning, and reassembly as part of my 97,000 mile overhaul.