I agree with David12345 and dox about using a gasolone treatment for a wonky fuel gage. It's conventional wisdom on the Corvette C5 Forum to use Techron to cure this problem. It worked for me. Someone posted a picture of a crudded up reostat that is part of the sending unit and speculated that it might be the sulphur in the gas causing it. Later models changed materials to prevent this. Buying a small bottle of Techron and using the correct number of ounces for the size of your fuel tank would be an inexpensive fix if it works, and shouldn't cause any problems if it doesn't.
I won't mentioned carrying around a small bottle of gas to get you to a station due to the danger involved. Oops! I guess I did.
A) The fuel injector / fuel system cleaner would be an easy thing to try.
B) The fuel pump/sending unit is held and sealed with a large plastic nut above a gasket or O-ring requiring the special spanner tool to remove without damage. This special tool is available. When I get the tool I'll be able to remove the assembly and evaluate my options. It could be the sending unit strip could be removed and cleaned with acetone with less degeneration than the abrasiveness of the Scotch Brite treatment. I could possibly put the strip into an ultrasonic cleaning tank, but I would be concerned about otherwise breaking-down the construction of that laminated and riveted sub-assembly I have seen pictured on the internet.
Also, I would be concerned about using the aggressive solvents in the entire tank with unknown constructions/materials/seals/hoses in the plastic fuel cell, and fuel pump assembly. That risky choice is playing russian-roulette with lots of potentially incompatible materials in a way that could force the choice to replace all those assemblies, and even screw up other parts of the fuel system such as the fuel injectors.
I had an old car with a faulty, but not completely failed, sending unit. When it started having injector problems I tried the quick fix of Chevron Techron fuel system cleaner. Not only did this address my injector problems, but I also noticed the fuel gauge became reliable and accurate. That car needed the additive every six to nine months (and it seemed highly dependent on how often I filled up at KwikTrip) to treat both the injectors and the sending unit.
What mechanical parts are in the fuel tank and how easy is it to remove? Perhaps a 60/40 mix of gasoline/acetone could be agitated around in the tank to break down the varnish? Maybe someone has a way of placing an ultrasonic cleaning transducer in the tank for this purpose? Of course, the cleaning agent depends on the plastics, o-rings and seals used in the tank, pump and sending unit.
In warmer weather, I often get 42-45 mpg with the V-Rod at modest, constant highway speeds of 45-60 mph with gasoline prior to gasoline suppliers adding around 10+% alcohol. In warm weather, I normally get 33 mpg around town. Travel in the winter has more fuel enrichment, cold lower-pressure stiff-flexing tires, and an engine that never gets up to temperature for worse specific fuel efficiency. Additionally, alcohol lowers the BTU per gallon and requires a richer mixture for another double whammy on resultant mileage. With winter driving, winter fuel blends, and modern fuels with more alcohol, both Harley's (V-Rod and Dresser) get relatively poor mileage in the winter. This can put the mileage down around 25 mpg. (Still better than one of our two cars.) Mileage variation may be less of an issue, if I didn't choose to also ride in cold weather.
But that's my point . . . I don't know the precise mileage, which varies depending upon temperature, winter fuel blend, driving style, and fuel injection compensation. I believe, that's what a gas gauge is for. Naturally, it is less critical to monitor this fuel level closely, if there is a larger tank for a range with a bigger refill range buffer, OR a fuel reserve that tells you to get fuel NOW. I do have a redundant back-up low fuel idiot light . . . but it is tied to the same defective fuel gauge sending unit; so, it is on most of the time and useless!
I have a 1995 Sportster which has the factory gas tank that holds 3.2 gallons. This bike has never done better than 35 mpg since new. I installed a performance carb a few years ago and mileage dropped to around 30 mpg. I feel your pain, but I have learned to not to ride over 75 miles or so without filling it up. I reset the trip odometer at each fill up and use that as my gas gauge. A gas gauge is nice to have, but Harley never put one on a Sportster so I have learned to live without it.
I'm still trying to grasp having a 25mpg motorcycle. (102 miles/3.8gal) My Evo FXR has a 3.8gal tank and got around 40mpg stock, and closer to 50 after putting on a header and changing the cam. Granted it's not a tire shredder either but your VRod reminds me of the range I got with the ironhead sporty I had with a 1.75gal peanut tank. The solution for that was a faux tool bag you put on the forks that held a half gallon or so of gas. Doesn't seem like a lot but it put me just over 100 miles. That's long enough between stops when you're riding the likes of an ironhead sporty.
First thought that comes to mind in your case is see if you can secure one of those assemblies to dissect and come up with a better solution (maybe a dead one from a mechanic). Over the years I've done a few fuel pump/gauge sender jobs on cars and motorcycles and there's never that much to them. I would bet you might be able to modify and retrofit a different sender into that assembly.
I had no idea VRods were so thirsty. I appreciate my ~50mpg 80 inch Evo even more now.
I had one of those $100 cars. It was a 78 Chevy Malibu. Not only did the gas gage not work, it also had a separation in a weld seam at about the 3/4 full point of the gas tank. Replacing the tank was cost prohibitive, so I kept it about 1/2 full at a max and a mileage log to keep track of when to put 5 more gallons in it. On the plus side, it had a V8 350 in it that put out plenty of horsepower when it was needed.
I agree. Reliability is one thing when it sends you back to the shop for minor fixes, but it's another altogether when it puts you in a position where you're trying to calculate in your head how much fuel you have left. I've had cars that didn't have working fuel gauges, but the entire cars were worth about $100. In a $26K bike, that's not acceptable.
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