Most of the water in the tank problems come from contaminated tanks at the gas station, not from condensation in your gas tank.
Keeping Gas Tank Full during Winter on newer cars
- Thread starter chefwong
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Had the orig 13 year old fuel pump fail in my '88 S-10 a couple of years ago, at 93k miles. Just quit one afternoon, no warning whatsoever, when I went out to fire it up (right after filling the tank). Towed it to the repair shop and managed to get the whole tank down, still full BTW, using a transmission lift. Motor in the pump just flat wore out. Motor armature rattled inside when shaken. Amazing thing was, when we got it down and took out the fuel pump-gage sender assembly and looked down into the tank, expecting to see a layer of sediment on the bottom, it was perfectly clean inside, nice and shiny, not a trace of crud, sediment or anything there! Nothing on the pickup screen either.
I "used" to run mine down within a gallon or two to near empty, but nowadays when either of my vehicles gets near the 1/4 mark that's when I pull in and top it off. The gasoline will act as a heat sink for the fuel pump and the more full it is, the cooler the pump runs. Gotta buy the gas eventually anyway, so it's just cheap insurance.
[ December 24, 2004, 11:13 AM: Message edited by: tblazed ]
I "used" to run mine down within a gallon or two to near empty, but nowadays when either of my vehicles gets near the 1/4 mark that's when I pull in and top it off. The gasoline will act as a heat sink for the fuel pump and the more full it is, the cooler the pump runs. Gotta buy the gas eventually anyway, so it's just cheap insurance.
[ December 24, 2004, 11:13 AM: Message edited by: tblazed ]
had a similar experience in my '93 dodge dakota. fuel pump finally died after 120,000 miles. i had intermittent operation/low pressure (it would barely idle and the fuel pressure jumped around quite a bit).
dropping the tank and looking around inside it was very clean down there. i was going to empty the tank and try to remove any debris but there didnt seem to be any point. the oem pump had (what appeared to be) a fine brass screen at the bottom of the pump assembly. the new pump from napa has a pleated paper filter. i suppose with the oem pump you need another filter after the pump to catch the really small stuff. the paper filter on the napa pump seems like it would catch almost everything before it was pumped.
dropping the tank and looking around inside it was very clean down there. i was going to empty the tank and try to remove any debris but there didnt seem to be any point. the oem pump had (what appeared to be) a fine brass screen at the bottom of the pump assembly. the new pump from napa has a pleated paper filter. i suppose with the oem pump you need another filter after the pump to catch the really small stuff. the paper filter on the napa pump seems like it would catch almost everything before it was pumped.
I have seen several mid 90's Taurus's that were used by relatives who insisted on always running around on less then half a tank (never had any $$ on them) and usually keep driving with the low fuel warning light on. Both of them required new fuel pumps w/i months of each other (around 50K miles).
I had a roommate one time with a Nissan pickup and he never had more than 1/3 of a tank in it. Riding to work one day carpooling we came to a nice halt in the middle of rush hour traffic in near zero weather.. frozen line. He was also too cheap to buy any gas line antifreeze as well even after it was towed to the dealer and left inside to warm up. He did however, keep more gas in it from then on.
I have seen alot of new cars are using to plastic tanks instead of metal and I would assume the temperature variations would be less with the plastic and thus less of a condensation issue.
I had a roommate one time with a Nissan pickup and he never had more than 1/3 of a tank in it. Riding to work one day carpooling we came to a nice halt in the middle of rush hour traffic in near zero weather.. frozen line. He was also too cheap to buy any gas line antifreeze as well even after it was towed to the dealer and left inside to warm up. He did however, keep more gas in it from then on.
I have seen alot of new cars are using to plastic tanks instead of metal and I would assume the temperature variations would be less with the plastic and thus less of a condensation issue.
It seems to me that if you never run it low, you're just accumulating more contaminents over time. The next time you forget to fill up early, your likelyhood of problem will be greater. I just run it down and ussually use FP.
An advantage of higher fuel tank level is reduced vapor space. Every time the tank cools off, the vapor in there shrinks due to two effects. The condensing of light hydrocarbons back into the fuel, and the natural contraction of cooler air. Fresh air is drawn into the tank through the carbon canister.
Upon reheating, the vapor expands, and goes out through the carbon canister. The light HC's are caught in the can and reburnt. More heat/cool cycles can draw water in and force light HC's out.
In the winter, the light HC's are necessary for good cold starting. With a low tank, there's more vapor so more losses, and with less fuel, less light HC's to lose...a double whammy.
Keeping the tank as full as practical keeps the fuel fresher.
On fuel-injected cars this is important too. If the tank gets ot 30F or so at night, during the run, fuel is circulated through the rails and warms up...beyond the ambient temperature. The vapor loss can be pretty high.
When it's col outside, there is very little water in the air (even at high RH). So, water is less of a problem in the winter. Fuel has a designed ability to absorb some water.
With pressure to reduce emissions, fuels are being blended with fewer light HC's, so preserving them will only become more important.
Upon reheating, the vapor expands, and goes out through the carbon canister. The light HC's are caught in the can and reburnt. More heat/cool cycles can draw water in and force light HC's out.
In the winter, the light HC's are necessary for good cold starting. With a low tank, there's more vapor so more losses, and with less fuel, less light HC's to lose...a double whammy.
Keeping the tank as full as practical keeps the fuel fresher.
On fuel-injected cars this is important too. If the tank gets ot 30F or so at night, during the run, fuel is circulated through the rails and warms up...beyond the ambient temperature. The vapor loss can be pretty high.
When it's col outside, there is very little water in the air (even at high RH). So, water is less of a problem in the winter. Fuel has a designed ability to absorb some water.
With pressure to reduce emissions, fuels are being blended with fewer light HC's, so preserving them will only become more important.
Lubircation of the pump is more important than cooling. We all know the 5 elements of attrition: friction, heat, moisture, vibration, dirt. So in reality, everyone here is correct. Some owner's manuals will outline lack of lubrication as the main reason to keep your fuel somewhere above 1/4 tank.
Now, how much will such "abuse" shorten the life of a fuel pump? Clearly not that much as most people I know have run their tanks low countless times after filling up at mousehole gas stations, through hot and cold, around turns and whatnot, for 100K+.
If you're a maintenance junkie, I'd keep that low fuel light off. It's about the most control you have.
Now, how much will such "abuse" shorten the life of a fuel pump? Clearly not that much as most people I know have run their tanks low countless times after filling up at mousehole gas stations, through hot and cold, around turns and whatnot, for 100K+.
If you're a maintenance junkie, I'd keep that low fuel light off. It's about the most control you have.
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