Fuel Warning Light - How many Gallons remain when comes on?

[Zoe Saldana]

I need to know how many gallons are in the tank when the Fuel Warning Light comes on. I usually, don't go that low.

My 2500 has a 31 gallon tank and I vaguely remember in the past when the light went on I was able to put in 25+ gallons which would mean about 6 gallons or a bit more (because I took some time to get to the gas station).


What are your thoughts?

Thanks

 

[EdGs]

On my '15 with the 26 gallon tank, I think I have been able to put in 22 or 23 gallons or so if mine has been on, so that would be 3 to 4 gallons left.

I wouldn't trust it though, because my evic would be showing 25 miles or so left. Scares me to run that low, for sure, and not good for the pump either, IMO. The fuel keeps the pump cool.

 

[RamDiver]

I need to know how many gallons are in the tank when the Fuel Warning Light comes on. I usually, don't go that low.

My 2500 has a 31 gallon tank and I vaguely remember in the past when the light went on I was able to put in 25+ gallons which would mean about 6 gallons or a bit more (because I took some time to get to the gas station).


What are your thoughts?

Thanks

Many years ago I drove a smaller truck 'wanna be' with a small gas tank. I used this truck for many road trips to locations without 24 hour gas stations.

This was commonplace in many rural areas of Ontario in the 80s.

After playing a similar game while trying to determine the truck's range, I filled a gerry can with gas and drove until the low fuel light illuminated.

I never required to use the backup fuel but it made testing much less risky.

I recorded the mileage when the light illuminated and refilled the tank at the next opportunity.

A bit of basic math and I learned the actual volume of the reserve fuel supply.

AFAIK, the mpg displayed on the EVIC is usually on the generous side but with a few basic calculations and the trip odometer, you can get very close to the actual mpg.

There are also many useful apps like FillUp or Fuelly to assist on tracking your truck's fuel economy.

.

 

[olyelr]

Only way to tell for sure…once the gas light comes on, reset the odometer and then run it completely out of gas. Just keep a full gas can with you when you do it haaaa.

 

[GTyankee]

When my tank reads 1/4, i don't wait until the RED light comes on.

It is like phone money, always have CASH phone money

Chrysler Fuel Pumps get too warm, if there is no Fuel to keep the pump COOL

I just had my Fuel Pump replaced,. it was Recalled

In the last few months, I have not been any where, where there was a lack of Fuel Stations, i usually check my fuel gauge every morning.

I needed to see a couple of Doctors & i saw the warning light after the last appointment.
I was happy that there was a Station that sells #2 diesel only 5 miles away & all but the last mile was down hill.
I did not want to damage or destroy a brand new pump.

I came too close to running out of Gas with my last Ram,
Driving through Texas & the Red light came on,
A road sign read that there was gas at the next Off Ramp, the whole town was boarded up.
Another road sign read that the next town was the last Gas Station for 50 some miles, that station was also closed.

I looked around & all that i could see was some cattle &
Oil Derricks in the distance.
It was late August in Texas, i did have plenty of water, soda, & beer.

I decided to try to make it nearer to Van Horn , Texas & i knew there was not a chance that would happen, but i would be closer to Interstate 10, where there would be more traffic & a better chance to flag some one down.

Play with your vehicles fuel if you want
Just pick a good area to do your

Hypermiling​

 

[gtomike60]

On my 2012 Power Wagon with 34 gallon tank,it'll take 26 gallons when the low fuel light comes on

 

[2003F350]

I've found that it varies from vehicle to vehicle, even if they're the same model. And the EVIC is NEVER correct. I've seen some DTE displays go to zero and keep running, I've seen others that the truck runs out of fuel while reading 50+ miles to empty.

They're warning lights, not precise indicators. They're there to tell you 'HEY THIS IS GETTING LOW, YOU SHOULD FILL UP SOON.' They're not something to live and die by.

FWIW I rarely let my vehicles get below half unless I'm on a trip, in which case I'll let them dip down toward a quarter. Peace of mind knowing I should be able to get anywhere I need to in an emergency without having to stop for fuel.

 

[Scottly]

Chrysler Fuel Pumps get too warm, if there is no Fuel to keep the pump COOL

One of my favorite of the "tall tales". If the pump sits at the top of the tank, with the pump motor protruding downward a couple of inches, after fuel quantity dips below 3/4 tank, the pump is not being "cooled" by the remaining fuel. Guess what? It doesn't need to be cooled. The rest of the assembly that IS hanging down...the pickup tube, sock, gauge parts, etc., don't do anything to aid in cooling. The real issues with running a tank too low is the air that is sucked up...cavitation. Too much cavitation leads to fuel starvation..."Out of gas" while the tank still has some in it. Read any ops manual for an airplane....They always list fuel capacity and total usable. That normally varies by a few gallons. There's a reason they list it that way.

 

[Bigskyroadglide]

On my truck it's approximately 50 miles. At 15 to 18 miles to the gallon depending on freeway or stop and go it's 3 to 4 gallons of the 26 gallon tank. So approximately 4 gallons

 

[2003F350]

One of my favorite of the "tall tales". If the pump sits at the top of the tank, with the pump motor protruding downward a couple of inches, after fuel quantity dips below 3/4 tank, the pump is not being "cooled" by the remaining fuel. Guess what? It doesn't need to be cooled. The rest of the assembly that IS hanging down...the pickup tube, sock, gauge parts, etc., don't do anything to aid in cooling. The real issues with running a tank too low is the air that is sucked up...cavitation. Too much cavitation leads to fuel starvation..."Out of gas" while the tank still has some in it. Read any ops manual for an airplane....They always list fuel capacity and total usable. That normally varies by a few gallons. There's a reason they list it that way.

Okay but your information on how automotive fuel pumps works is...faulty. Not sure if this will let me post the pic of a Ram fuel pump but I'll give it a go.


See that assembly? The canister at the bottom houses the pump, and it's a 2-stage pump. It rests on the bottom of the fuel tank, and the springs on the tall shafts push it against the bottom a bit. Basically ALL automotive pumps are this way today.

One stage of the pump brings fuel into the canister via an inlet on the bottom of the canister that is covered by the prefilter screen. This fills the canister and keeps cool fuel around the outside of the fuel pump. This fuel is constantly replenished as the second stage does its job.

The second stage of the pump sends fuel from inside the canister up that black hose and out the top cover plate to the fuel line on the frame rail. That silver thing is a pressure regulator to keep fuel pressure from building up too high.

That's it. That's how modern fuel pumps work. Cavitation on modern pumps is almost NEVER an issue unless the pump housing is damaged. The pumps don't get to run hot because they are ALWAYS sitting in fuel that is constantly flowing past them unless you run the tank dry. It's how they stay cool and run for a LONG time.

Now, yes, they're electrical components, and some will fail sooner than others. But it isn't because they 'run hot,' it's a fault of mass-production. Some will get a bearing that is too tight or too loose, the motor coils might be too tight or too loose, hard to say, but the vast majority will function as intended for a LONG time without giving any issues.

 

[Different Drummer]

Mine will take 26 gallons when the fuel warning light comes on. I have a 32 gallon tank. I have a couple of times run the truck for 100 miles after the fuel warning light illuminates and have never managed to pump 30 gallons into the tank.

 

[Scottly]

Okay but your information on how automotive fuel pumps works is...faulty. Not sure if this will let me post the pic of a Ram fuel pump but I'll give it a go.
View attachment 544277

See that assembly? The canister at the bottom houses the pump, and it's a 2-stage pump. It rests on the bottom of the fuel tank, and the springs on the tall shafts push it against the bottom a bit. Basically ALL automotive pumps are this way today.

One stage of the pump brings fuel into the canister via an inlet on the bottom of the canister that is covered by the prefilter screen. This fills the canister and keeps cool fuel around the outside of the fuel pump. This fuel is constantly replenished as the second stage does its job.

The second stage of the pump sends fuel from inside the canister up that black hose and out the top cover plate to the fuel line on the frame rail. That silver thing is a pressure regulator to keep fuel pressure from building up too high.

That's it. That's how modern fuel pumps work. Cavitation on modern pumps is almost NEVER an issue unless the pump housing is damaged. The pumps don't get to run hot because they are ALWAYS sitting in fuel that is constantly flowing past them unless you run the tank dry. It's how they stay cool and run for a LONG time.

Now, yes, they're electrical components, and some will fail sooner than others. But it isn't because they 'run hot,' it's a fault of mass-production. Some will get a bearing that is too tight or too loose, the motor coils might be too tight or too loose, hard to say, but the vast majority will function as intended for a LONG time without giving any issues.

I stand corrected and apologize for my misinformation.

 

[Zoe Saldana]

On my 2012 Power Wagon with 34 gallon tank,it'll take 26 gallons when the low fuel light comes on

Thanks.

I need to know because I want to use Cataclean and it says to get to 1/4 tank and pour in and drive around some before re-filling. And 1 bottle for 4 gallons, so if the light goes on at 26 that's 8 gallons so I need 2 bottles.

Amazon.com

 

[Zoe Saldana]

Mine will take 26 gallons when the fuel warning light comes on. I have a 32 gallon tank. I have a couple of times run the truck for 100 miles after the fuel warning light illuminates and have never managed to pump 30 gallons into the tank.

Thanks.

I need to know because I want to use Cataclean and it says to get to 1/4 tank and pour in and drive around some before re-filling. And 1 bottle for 4 gallons, so if the light goes on at 26 that's 8 gallons so I need 2 bottles.

Amazon.com

 

[Dean2]

You reason for wanting to know makes sense, however for decades I have carried 5 to 10 gallons of gas in Jerry cans in my pickups. I have never had to use it myself, but I have sure saved a lot of other folks who tried to push the empty envelope. I have also experimented with my new 2500, just because I have the safety factor. When the gas light comes on, I have about 5 U.S. gallons left. I have the 32 gallon tank.

Generally however, I re-fuel when I hit 1/2 tank, the top half costs the same to fill as the bottom half. Also, there are lots of steep and long up and downhill runs around here, the last few gallons may be hard for the pump to pickup if the gas is all at the front or back of the tank. I also carry a bulk station gas card, as lots of areas around here do not have 24 hour gas.

 

[rzr6-4]

I have a 33gal tank and I have put 31gal in more than once and have yet to have the light come on. 2gal in reserve with my current ~12~ mpg is not much of a buffer.

Not something I would mess around with if possible.

 

[2003F350]

I stand corrected and apologize for my misinformation.

It's no problem, I just wanted to set the record straight for everyone on how modern fuel pumps work. It's been this way since port fuel injection came out, I had a '96 GMC Jimmy with this style of pump on it. Because most people don't do their own work, most people don't know how they function. If I hadn't had to replace a couple and didn't work for a place that designs fixtures for assembling the new style pumps, I wouldn't know how they function either, because up until that Jimmy, the last thing I did a fuel pump on was a '94 GMC 3500 with a TBI 454. THAT truck had a sending unit at the top, and the pump just...dangled...in the tank, attached to the end of a steel tube. It sat inside a 'baffle' inside the tank, but it was a single stage pump and only sucked up fuel from the bottom.

 

[Different Drummer]

Thanks.

I need to know because I want to use Cataclean and it says to get to 1/4 tank and pour in and drive around some before re-filling. And 1 bottle for 4 gallons, so if the light goes on at 26 that's 8 gallons so I need 2 bottles.

Amazon.com

To try to get as accurate check as possible I made sure to fuel up just as soon as possible after the reserve / warning light came on. I did this three times and always within 10 miles from when the light went on. All three times to fill the truck it took 26 + or - a few tenths. Of course there are other variables like the difference in pumps used. I wanted this information because I do a lot of long distance travel and wanted to have an accurate figure for what was remaining in the tank after the warning light came on.
It seems to be pretty accurate as far as I can tell.
Looks like you might have a HD truck and mine is a 1500 with the 32 gallon tank an option that I ordered. I cannot attest to whether or not the difference in trucks makes a difference.

 

[Gr8bawana]

Has anyone ever read in their owners manual to never let the fuel get down below a certain level because the fuel pump will be damaged? No.
It just doesn't happen.
I don't know how this myth got started to begin with. Maybe if an electric fuel pump ran for a long time pumping nothing it might be damaged.

 

[2003F350]

To try to get as accurate check as possible I made sure to fuel up just as soon as possible after the reserve / warning light came on. I did this three times and always within 10 miles from when the light went on. All three times to fill the truck it took 26 + or - a few tenths. Of course there are other variables like the difference in pumps used. I wanted this information because I do a lot of long distance travel and wanted to have an accurate figure for what was remaining in the tank after the warning light came on.
It seems to be pretty accurate as far as I can tell.
Looks like you might have a HD truck and mine is a 1500 with the 32 gallon tank an option that I ordered. I cannot attest to whether or not the difference in trucks makes a difference.

Yours is REPEATABLE. They all are - they'll always come on at about the same time every time on the same vehicle. But they're far from ACCURATE, because on a truck identical to yours, that light will most likely come on at a different time.

Sorry, not trying to pick on anyone, it's just there's a difference between accurate and repeatable. Something can be 100% repeatable (always give the same reading) but not accurate (the reading could just be wrong). It can also be accurate but not repeatable (it'll be within +/- 5% of the correct reading, let's say, but every time it will read something different). Fuel pumps and low fuel warning lights are NOTORIOUS for being inaccurate but repeatable.