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OnlineHelp, Mechanic
Category: Car
Satisfied Customers: 3423
Experience:  Mechanic
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2005 Kia Spectra5: It has 62,500 miles on it now

Customer Question

I have a 2005 Kia Spectra5. I just bought it about 3 weeks ago so I don''t know much about its history. It has 62,500 miles on it now. The problems that I am having is an intermittent fuel light even when there is plenty of fuel in the tank and am also experiencing what is in my opinion poor fuel economy. Over the past 5 tanks I have averaged 19 to 23 mpg (mostly highway driving). Shouldn''t it be doing better than this? I have already checked the most obvious basics (tire pressure, air filter, oil changed, etc...)
Submitted: 9 years ago.
Category: Car
Expert:  OnlineHelp replied 9 years ago.

Hello and thank you for choosing Just Answer.

Let's address the first issue, the fuel light. There is a fuel sending unit that is located in the fuel tank. It sends fuel level reading to the fuel gauge, if the fuel sending unit is bad or is malfunctioning you will get bad fuel readings and fuel lights even tough the tank is full. In order to solve this problem you will need to have the fuel sending unit replaced.

Now to the second issue, fuel consumption. The advertised estimated MPG is 25mpg/ 32mpg, now this is advertised. They get 32mpg on a perfect straight highway without traffic on it. This is going to be nowhere near possible to reach. They however are allowed to advertise this, since they can prove (again on a perfect stretch, no up or down hill) the MPG. Realistically speaking your car should get just a notch above what it is getting. Keep in mind , the more mileage is put on your car the less MPG you will see. The spark plugs , oxygen sensor, air flow sensors all start to get readings that are not exact. Your oxygen sensor start to build up deposits and the car Air/Fuel mixture suffers. This will cause lower MPG.

Do a tune up, run some good fuel cleaner through the system (seafoam) and your MPG should improve.

Customer: replied 9 years ago.
If the fuel sending unit is bad and thinks that there is a low fuel condition then shouldn't this show on the gauge as well? There has been no erratic behavior on the gauge, just the light. The light will sometimes stay on for a few seconds and sometimes it just flickers or illuminates very dimly. I have heard that a lose gas cap can cause this but I have checked that numerous times. Is there any thing else it could be? Is it possible that what ever is causing the fuel light to come on is also the culprit of the poor fuel economy?
Expert:  OnlineHelp replied 9 years ago.

No a loose fuel cap will cause the check engine light to come on. The Evap system registers a leak in the system due to pressure escaping from the gas cap. This usually triggers a check engine light and a code P04##. The light that you are getting however is a different light. You are having the low fuel level light, which is controlled by the input of the fuel level sensor.

I can't quite say if this is related to the bad fuel consumption or not. If there is dirt in the fuel tank or pool electrical connection at the level sensor it may trigger the light to come on. It won't always cause the gauge to act up, just the light. What you have to know is that the only thing that can trigger that light is the level sensor or a bad connection in the cluster itself.

Customer: replied 9 years ago.
Relist: I prefer a second opinion.
Customer: replied 9 years ago.
Relist: I prefer a second opinion.
Customer: replied 9 years ago.
Relist: I prefer a second opinion.
Customer: replied 9 years ago.
Relist: I still need help.
Installed new Bosch plugs and wires and added a can of seafoam to the fuel tank. Two tanks later still no improvement in fuel economy...