Frozen fuel line. Fill up tank or don't fill?

Guys, my MIL drove her car into her garage on Friday night and on Saturday morning it wouldn’t start. Hyundai Tucson.

I went over there yesterday and put the battery charger on it, but the battery was fine and I just replaced it 3 weeks ago anyway. Engine cranked over, but would not start or even pop. Left charger on the battery just in case.

I dumped a container of HEET in the gas tank and put my shop heater in her garage. It’s a single car garage so I managed to get up to about 40, then ran an electric heater overnight to keep the temp up.

I went over this morning and after some crank/start/shudder/die, it finally fired up and idled. Pushing on the gas would cause it to die. After 10 mins at idle, it finally would rev up and now it idles normally and I just drove it about 10 miles with no issues. I added another container of HEET to really get it working as my conclusion is the fuel line or filter had water in it and was frozen.

MIL drives only about 50 miles a week and she’s scared of going in the ditch and running out of gas before the cavalry arrives, so she constantly tops off the tank with a few gallons. I know, not good as far as getting rid of condensation goes. I have warned her about this but even with cell phone and a trunk full of blankets, she’s convinced she could be stranded in a ditch somewhere in the wilds of Oakdale for 3-5 days before rescue.

My question: Tank is currently about half full. Is it better to top it off with fresh fuel now, or run it down to try to burn off more of the water? I’m thinking run it more and burn off more of the wet gas, but will that just risk a re-freeze even though there’s HEET in the gas now?

I would fill it up and try to put some miles on it. Then fill it again.

When I was learning to fly the rule was ALWAYS, regardless of how much fuel I/we uesed, you had to top the tanks off after completing flight. I was specifically told that this was to avoid room for condinsation to build.
I have never flown in winter weather so don’t know if that would affect it differently.

I’ve also been told that full tanks leave less room for condensation. Idling in cold temps create the most. My thought, fill it up, drive it around and put some miles on it. Then fill it up again. The heet should mix with all the gas and help.

Topping off the tank isn’t her problem, that’s the correct technique. She got bad gas from somewhere.

Filling the tank is the correct thing to do. The more gas, the less space for or condensation.
I’d guess her car didn’t have a frozen fuel line. It was probably flooded.

Keeping in mind, the issue isn’t preventing condensation.

The SUV already has wet gas. No way of preventing it now.

The question is what’s the best way to burn off this wet gas and prevent a refreezing of the fuel line.

Fill it up and dilute it down. Also add the correct amount of heat and don’t get gas at the last place.

Take it on a road trip and drive it till it’s less than 1/8th of a tank and fill with non oxy from a busy gas station that cycles through fuel and do the samething again. The temps should be warming up enough in the next couple weeks to hopefully eliminate the issue. She might want to get fuel at a different place than normal from here on out. Agree that filling the tank is typically a good thing to reduce condensation problems. But some stations don’t cycle through their fuel quick enough and the problem is the fuel quality, not the filling of the tank. Good luck with it and it’s a butt pain to do.

Why leave crap fuel in the tank? Why dillute crap fuel to “less crappy” fuel?
Start driving, fill up when darn near empty.

Another option is siphoning the old fuel out till the tank is as empty as you can get it, then refilling with fresh fuel. But there’s the old fuel to deal with and it’s challenging if you’re not use to doing it.

I would lean towards it was an electronic throttle issue.

TheFamousGrouse wrote:

Keeping in mind, the issue isn’t preventing condensation.

The SUV already has wet gas. No way of preventing it now.

The question is what’s the best way to burn off this wet gas and prevent a refreezing of the fuel line.

How do you know it has water in the gas? I think you’re barking up the wrong tree.

I’m thinking I would fill it up, add seafoam, and put some miles on.
Just my $.02

suzuki wrote:

I would fill it up and try to put some miles on it. Then fill it again.

This.

Since the weather is getting warmer I’m going to drive the SUV for the rest of the week and see if I can run down the tank. If something happens and it dies again I’d rather be the one sitting on the side of the road waiting for help.

grubson wrote:

<div class=”d4p-bbt-quote-title”>TheFamousGrouse wrote:</div>
Keeping in mind, the issue isn’t preventing condensation.

The SUV already has wet gas. No way of preventing it now.

The question is what’s the best way to burn off this wet gas and prevent a refreezing of the fuel line.

How do you know it has water in the gas? I think you’re barking up the wrong tree.

A vehicle that gets driven only a few miles a day on average and rarely gets the gas tank run down past a quarter never a lick of trouble until we got to the coldest two days of the year and suddenly it won’t start. No I don’t know it was wet gas but it seems like that would be the top of the suspect list. Then I sit at in a warm garage for two days add heet and suddenly the problem disappears.

Which tree do you think I should be barking up?

Gas and water don’t mix. The water will settle to the bottom of tank and will be picked up 1st by your intank fuel pump. Filling the tank will do nothing to ‘dilute’. Just use your additive to break up the water molecules so the can get through the injectors and be burned off.

If she lives in Mn, all gas has at least 10% alcohol already. Unless she buys 91 octane. So adding Heet is useless. It is possible she got bad fuel especially if the tanker was filling the stations tanks while she was pumping hers. It’s more likely she flooded it while trying to start it when very cold and not having it plugged in. Putting the car in the warm garage for a couple days made the fuel more volatile and made starting a lot easier. I’m guessing it smoked pretty heavy after it started till it cleaned all the excess fuel out?

I’d also say to drive until empty but its a Hyundai Tuscan, it’d be damn near April defore it ran out. Incredible mileage.

I’m guessing it was flooded as slowpoke mentioned. It’s hard to say now because it’s running again.
I haven’t seen a frozen fuel line on a car in many many years. Too much alchohol in the gas now days for it to be a common issue. I see flooded cars in the cold weather daily. When it’s this cold the computers read coolant temp to determine fuel mixtures. Being this cold the computer compensates by adding extra fuel. If the idle control valve or throttle body is slow to respond by giving the engine air that extra fuel will foul the plugs.
If it happens again try holding the accelerator pedal to the floor while cranking the engine. This will put the injectors into de-flood mode and shut them off to allow the plugs and combustion chambers to clear out.

Does water float on gas or gas float on water? I’d think any water in your fuel system would’ve the first to go. Like others suggested, I’d run it for awhile than keep the tank always above 1/2 full…but I only sleep at a holiday in.

The way you described how it ran after it started sounds more like the engine was flooded. I would be checking the oil, my SIL had a car that would flood bad enough that gas would get past the rings and dilute the oil.

Buddies Hyundai did that every once in a while if say he started the car and moved it in to the garage and shut it off with in a minute or 2.
They told him to floor it and crank it till it popped off then drive it to clear it out. They flood them selves electronically. Mitsubishi is known to do the same

I’m thinking flooded also.
I remember in 1988 had new f150 got real cold like this dang thing would flood out on occasion. Had swap spark plugs to get it going. Comman problem back then for many fuel injection vehicles.
Just a thought.

Grouse i would say it was a little flooded.I assume you used Heet that has the isopropyl alchohol.I would fill it up and drive it.If does have a little water in it that should remove most of it.
There are some injector cleaners that i believe help remove moisture also.

big_g wrote:

I would lean towards it was an electronic throttle issue.

I agree on electronic issue first. When its this cold, sensors flake out and crap happens. We’ve had the same issue with bringing a -20 degree car in the garage and then heating to 35-40ish and it floods out before starting.

Any chance it threw an error code? My daughters Honda didn’t put out any codes when it wouldn’t fire. Let it sit for most of the day and tried again. Fired up (reluctantly) and never had an error code

I agree with slow poke. Gas with ethenol already has one gallon of alcohol or more per every 10 gallons of gas so adding HEET is a waste. Keep the tank full to avoid condensation. If not burning a tank per month might want to use non ethenol fuel. Sounds like flooding issue.

Grouse,
Gas now has ethanol in it, that is correct. It sounds like your MIL drives very little and the same thing can happen with the gas in her tank that happens with your boat, lawnmower, chain saw, etc. of things that set around for extended periods of time. Ethanol will separate and attract water. It is called phase separation. It will be like a cloud on the bottom of the tank. To eliminate it treat tank with isopropyl alcohol. Drive around and use it up. It could have been a frozen fuel line but it is not very common anymore. It could have been a coolant sensor, throttle sensor, or flooded as others have commented. It also could have been that the flash point of what was in the fuel was too diluted to ignite for starting properly.
Don’t have the MIL put isopropyl alcohol in every time she gets fuel either. Once at the start of winter and maybe 1 more time midwinter should take care of it.