I always fill my car right to the max. Is this going to damage the fuel system. I,ve HEARD that doing this can damage the fuel system evaporation cannister. Is this true? My car is a 2001 Honda Civic. If it is true,how would someone know if the evap cannister is ruined?
Can you damage your fuel system by over filling?
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Yes, it is true -- but it doesn't happen often.
On any car made during or after 1996 one will get a Check engine or Malfunction Indicator Light if the emission recovery system is damaged. Of course one would have to read the code, or get someone to do it, to know what caused the light to come on. It is not wise to assume that one knows the reason for the light to come on.
On any car made during or after 1996 one will get a Check engine or Malfunction Indicator Light if the emission recovery system is damaged. Of course one would have to read the code, or get someone to do it, to know what caused the light to come on. It is not wise to assume that one knows the reason for the light to come on.
I "over fill" to absolutely ensure that the tank is full so that my fuel economy mileage figures are accurate.
I don't see how it could cause harm. I do it not only for the MPG figure but because I always know when to fill up to get the best price and at times it could be a full week ot a little longer before the gas price gets to another acceptable and that extra gallon that I get in there past the first click of the pump makes the difference. I've never heard of a problem and most of the people I know fill it until it reaches the filler neck.
my mechanic tells me not to overfill because it can overpressurize the tank.
gasoline evaporates when its warm just like any rubbing alcohol. When you overfill you leave very little volume for it to expand. Plus overfilling may cause it to overflow. I usually never fill it beyond the first click but I seen people overflow and spill out onto themselves/around the vehicle creating a huge fire hazard.
gasoline evaporates when its warm just like any rubbing alcohol. When you overfill you leave very little volume for it to expand. Plus overfilling may cause it to overflow. I usually never fill it beyond the first click but I seen people overflow and spill out onto themselves/around the vehicle creating a huge fire hazard.
Basically what usually happens is the liquid is forced, usually by the pressure of expansion that daemonite refers to, into the evaporative emissions canister. This canister is filled with activated charcoal which is designed to store the fuel vapors. It is not designed for liquid. When the charcoal becomes saturated by the liquid it can no longer store and release vapors. The only solution is to purchase a new canister, and replace it.
On occasion the expanding liquid can damage some of the valves in the vapor recovery system as well.
I suspect this sort of damage occurs more frequently when the fuel tank is filled to the brim and then the vehicle is parked in the heat of the day. The chance of damage is lessened if the vehicle is driven some distance immediately after it is refueled.
Terry
On occasion the expanding liquid can damage some of the valves in the vapor recovery system as well.
I suspect this sort of damage occurs more frequently when the fuel tank is filled to the brim and then the vehicle is parked in the heat of the day. The chance of damage is lessened if the vehicle is driven some distance immediately after it is refueled.
Terry
Hmm....I don't see a need to do that to get accurate mpg...fill the tank..set your trip meter...fill-up again when low...then divide the miles on the trip meter by the gallons on new fill-up...has always worked perfect for me.
Some gas station fuel pumps cut out at different levels if you know what I mean ( some pump faster than others).
JHZR2
Staff member
I can understand that if a valve was brokem that there wouldbe a CEL for the evap system... however, if the charcoal gets saturated with liquid, it wont hold vapor anymore, and the purge process will likely be highly saturated with fuel vapors when the liquid fuel begins to evaporate out.
However, I dont see how inactivated charcoal would set off a CEL... If the valve isnt broken but the charcoal is useless, so what? Will that cause a malfunction? I dont see how it can...
Thanks,
JMH
However, I dont see how inactivated charcoal would set off a CEL... If the valve isnt broken but the charcoal is useless, so what? Will that cause a malfunction? I dont see how it can...
Thanks,
JMH
Even if you accurately fill the tank to the same level every time, it is better to get the fuel mileage averaged over many tankfulls, in which case only the accuracy of the initial fill and final fill will matter.
That's right. Filling it up "all the way" for MPG calculations purposes is just silly. You can't REALLY be sure you're filling it the same amount unless you cause it to spill out every time. There are other factors too, like how empty is empty, why the bottom of the tank always has a little gasoline left at the bottom, what the true capacity of your tank is, etc. It's just as accurate to do as jeremy says, even if it isn't perfect.
YOu will definitely cause harm to your fuel tank, charcoal canister and also fuel pressure system in your 2001 Honda Civic.
Hondas and Toyotas are now ODB-II compliant meaning that there are a lot more emissions control monitoring devices in your entire system, including your fuel tank and vapour recovery system. Consistently overfilling will trip your ODB-II monitoring causing lots of 4xx error codes, just like my sister-inlaw's Toyota Corolla.
Hondas and Toyotas are now ODB-II compliant meaning that there are a lot more emissions control monitoring devices in your entire system, including your fuel tank and vapour recovery system. Consistently overfilling will trip your ODB-II monitoring causing lots of 4xx error codes, just like my sister-inlaw's Toyota Corolla.
Thanks for the feedback guys/gals. I still maintain that the ONLY way to ACCURATELY check your fuel economy is to COMPLETELY fill your tank to the point where it slightly overfills - then you know for sure it's full. Even a 1/8 gallon or 1/2 litre difference in refueling techniques will throw off any accurate fuel consumption calculations IMHO. Obviously you will have better repeatability success if you use the same gas pump at the same gas station each time if you prefer to not overfill your tank when checking your mileage.
For what it's worth,I have always filed my car to the MAX (almost 300,000 kms) and have NEVER had any "error codes" come up - maybe I have been lucky?
JHZR2
I don't know that much about the evaporative emissions system monitoring to be able to explain to you how/if the light will come on if the canister is saturated with liquid. I do know that when that happens, in the cases I have been involved with, no light was necessary. The smell of gasoline was overpowering. The nose lead to the complaint and to the source of the problem.
It has never personally happened to me and I fill the tank all the way up most all the time. As I said in my first post, a failure of this type is not usual, but it can happen.
Terry
I don't know that much about the evaporative emissions system monitoring to be able to explain to you how/if the light will come on if the canister is saturated with liquid. I do know that when that happens, in the cases I have been involved with, no light was necessary. The smell of gasoline was overpowering. The nose lead to the complaint and to the source of the problem.
It has never personally happened to me and I fill the tank all the way up most all the time. As I said in my first post, a failure of this type is not usual, but it can happen.
Terry
I just fill until the fuel pump shuts off.
In 3 decades of filling until I could see the fuel I never had a problem, just accurate fuel economy data.
With newer cars I fill until the pump shuts off.
If I want an accurate measure to compare to the trip computer avg mpg display I use the same pump at the same station at the same flow rate.
In 3 decades of filling until I could see the fuel I never had a problem, just accurate fuel economy data.
With newer cars I fill until the pump shuts off.
If I want an accurate measure to compare to the trip computer avg mpg display I use the same pump at the same station at the same flow rate.
Car Talk (Click & CLack) always warns about damaging the evaporative emission control system, and advises you not to overfill. Don't know how much it costs to fix, but I think someone here will eventually find out. Overfilling also contributes to HC emissions, and if everyone did it would simply worsen pollution. JMHO
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