timn29 Posted July 25, 2004 Share Posted July 25, 2004 Has anyone noticed their 98 OBW or any other Subie gas gauge being inconsistnent? I neer notice this on my 88 DL. My 98 OBW's gauge will take a long time to drop throught first 1/4 tank then it seems to drop faster throught rest of the tank as if to compensate for the slower drop in the first 1/4. Ex: 1st 1/4~100+ mi. 2nd 1/4~75 mi. 3rd 1/4~50 mi. 4th 1/4~30 mi. this is all with varying driving conditions...mostly city and highway. Link to comment Share on other sites More sharing options...
frag Posted July 25, 2004 Share Posted July 25, 2004 My fuel gauge does exactly the same. Link to comment Share on other sites More sharing options...
Cougar Posted July 25, 2004 Share Posted July 25, 2004 I think these tanks have two sensors in them and it may be that one of them is not working correctly. I know from previous posters that these sensors are prone to have broken or dirty contacts. I think if one sensor is not giving the right resistance it may cause this kind of thing to happen. Just out of curiosity, do you know how much fuel the tank holds? Going by your miles shown and assuming you average 23 MPG that would make the tank capacity around 11 gallons and I'm pretty sure you would have at least a 15 gallon tank. Link to comment Share on other sites More sharing options...
THAWA Posted July 25, 2004 Share Posted July 25, 2004 It's setup like that because people don't like to see the actual gas consumption. Someone once stated that in lincoln or cadilacs or something they had a digital guage that showed the exact amout of gas in the tank and too many people were complaning that they'd just filled up the tank the morning and they were already down the first few notches by the end of the day. They were later recalled to show a less acurate gauge. Link to comment Share on other sites More sharing options...
timn29 Posted July 26, 2004 Author Share Posted July 26, 2004 I have a 13 gal. tank. BTW I've never seen my low fuel light come on and I have driven to the last mark on the gauge...does that info help any? Link to comment Share on other sites More sharing options...
blitz Posted July 26, 2004 Share Posted July 26, 2004 THAWA, that's interesting, not unlike the "dead-zones" on the temp & oil pressure guages. It's loud commentary about human nature, but troubling. If one of the options available on the build-sheet for a new vehicle was "true gauges", would anyone opt for it? The public loves good news, albeit B.S. Link to comment Share on other sites More sharing options...
timn29 Posted July 27, 2004 Author Share Posted July 27, 2004 in my case it's only good news for the 1st 1/4 tank, Link to comment Share on other sites More sharing options...
Guest jclay Posted July 27, 2004 Share Posted July 27, 2004 When the gauge in my 94 legacy gets to "E", i start watching the trip odometer, when it gets up to around 300 miles on the tank, i know its time for gas, usually by that time the gauge needle is WAY below the "E" The light also come on only when way below "E" my conclussion is that the gauges are very pessimistic, or designed that way so one never runs out of gas. Also, and i'm not sure if this is true for Subies, but the mech who worked on the Jetta i had previously told me to fill up when it got to 1/4 tank, as having fuel in the tank would protect the fuel pump by helping heat to dissapate, and by providing lubrication for the pump as well. (he was an old guy who only worked on VW/Audi, and really new his stuff) perhaps the "pessimistic" gauges are purposely that way to protect our fuel pumps. jared Link to comment Share on other sites More sharing options...
timn29 Posted July 29, 2004 Author Share Posted July 29, 2004 certainly sounds reasonable. so, how can you tell what kinda gas mileage you're getting if the gauge is inaccurate? For instance if I fill-up, run it down to 1/2 tank, then record mileage, then fill-up again, run it down to 1/2 tank then record the mileage. Add the 2 mileages together...is that accurate if the gauge is lowering slower in the 1st 1/2 tank? (Sorry if I confused you.) But you see what I'm saying? Link to comment Share on other sites More sharing options...
Commuter Posted July 29, 2004 Share Posted July 29, 2004 One calculates gas milage by distance driven over gas consumed. It has nothing to do with the gauge. Eg - Start with a full tank. Reset trip odometer. Drive 300 miles (or whatever). Fill up tank. Note how many gallons to fill the tank. Let's say 10 gallons. Therefore 300/10 = 30 miles to the gallon. What the gauge is reading when you fill up doesn't matter. What you can determine is some idea of the accuracy of the gauge. This comes back to the original post in the thread. If you have a 15 gallon tank (for example) and you have put in 10 gallons to fill it up, one would expect the gauge to have been reading 1/3 full (5 gallons were remaining). If it was reading otherwise, then there is a gauge error. My experience has been that gas gauges are not the most accurate, or linear of devices. It would not surprise me one bit that they are purposely non-linear. I can see how that would have come about, as also discussed in a prior post. Commuter Link to comment Share on other sites More sharing options...
timn29 Posted July 30, 2004 Author Share Posted July 30, 2004 Sometimes the answer is right in front of me. Thanks Commuter! and the rest of you guys. Link to comment Share on other sites More sharing options...
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