I have a 2005 Gmc sierra 1500 with the 5.3L vortec. Automatic transmission. Electric throttle body. It has 200,000 miles. When the gas gets to a quarter tank or less it had no power. When I throttle it bogs down and I can get loud popping noises. This only happens when had is at the level specified. It will also idle rough and consistently stay around 600rpm. What could cause this problem? It isn't throwing any codes
Check your fuel pressure when the tank is low.
You should never let a fuel injected engine get below 1/4 tank of fuel. Your 17 year old fuel pump is probably going out.
nonsense.
I have always used my entire fuel tank, and never, ever, had to change a fuel pump.
I agree with MMJ. I routinely get below 1/4 to just above the E and never had to change a fuel pump on any of my vehicles. But I never run on fumes, either!
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Now I probably jinxed myself for saying that.
I agree with doc - it’s best not to go bellow 1/4 of a tank.
Although I don’t think that this has a massive effect on the longevity of the fuel pump - it definitely helps make it last much longer (after 150k miles) due to the improved cooling.
(even on designs where the fuel pump sits in a “bath” of fuel, with a high fuel level, there’s much more thermal mass)
by the way, when my gauge is on the last tick (E), there is still around 1/6 remaining in the tank.
As long as fuel is flowing, the pump is cooling.
it definitely helps make it last longer
Insignificantly. No failures yet after 200,000 miles and 5 vehicles. Nobody else I know either.
I think it's an old wives tale from the days of steel tanks.
The tank is never truly empty
even on designs where the fuel pump sits in a “bath” of fuel, with a high fuel level, there’s much more thermal mass
irrelevant, and the drawing is horsedung. The pump is cooled by fuel flowing THROUGH it. You don't need the thermal mass of entire tank of fuel. I've seen BS come from this AGCO site before.
Insignificantly
Although I don’t think that this has a massive
So on this we agree that this does not have a noticeable effect, during the design lifespan.
But on many cars, with weak fuel pumps, it does allow the fuel pump to last longer.
For example, on Ford Of Europe (aka older Mazda) products, certain Corollas (like 09) this DOES have an impact.
The pump is cooled by fuel flowing THROUGH it
The fluid flowing through it is touching the plastic impeller, not the motor diving it.
You don't need the thermal mass of entire tank
Considering gasolines low thermal mass (1/2 of water), you need a significant level in the bath to keep things cool.
Baths and motors are often 10-15cm off the bottom, and that's 1/5 of a tank worth of fuel - on a regular compact sedan.
when my gauge is on the last tick (E), there is still around 1/6 remaining in the tank
again, depends on the car.
On my Kia 'E' with the 'Fill Up Now' message means about 2L (under a gallon, less than 1/21 of the tank), that's assuming the size states in the car spec is correct about it being a 45L tank.
Generally, keeping fuel above 1/4 is a good way to make your fuel pump last beyond its designed lifetime.
It definitely does not hurt.
You need to understand how pumps work. I highly recommend you open one up some day.
The pump, which is quite small -- about the size of a salt shaker -- easy to cool -- it is constantly in a bath of fuel. The body is made of metal. This bath has a one way valve, so it stays filled even if you take a sharp corner.
The fluid flowing through it is touching the plastic impeller, not the motor diving it.
Come on Dan. Don't BS me. Heat doesn't come from the impeller. Most of the heat is generated in the windings and maybe a bit in the bushings.
The roller vane pumping element is machined from a solid slug of aluminum, the bushings and valves are brass, shaft is steel, and the walls of the outlet are copper -- all EXCELLENT conductors of heat.
But most importantly, the fuel flows through the inside of the metal pump body, and around the armature. That means that the hot motor windings, and laminations are always in DIRECT contact with the fuel. The few joules of heat generated there is quickly carried away by the fuel to your engine.
The rest of the fuel in the tank does nothing.
Generally, keeping fuel above 1/4 is a good way to make your fuel pump last beyond its designed lifetime.
It definitely does not hurt.
Obviously I don't recommend running a pump so dry that it sucks air. But this 1/4 tank stuff is complete and uttter nonsense.
You will be absolutely fine running your tank to empty.
https://www.youtube.com/watch?v=WWDFAPXsk9s
On my Kia 'E' with the 'Fill Up Now' message means about 2L (under a gallon, less than 1/21 of the tank), that's assuming the size states in the car spec is correct about it being a 45L tank.
all tanks have reserve of about about 60 miles. Lets say you have a very efficient car that gets about 30 mpg. I bet there's a couple of gallons in there on 'E'.
I don't want to get into this to avoid any unnecessary drama.
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But on the topic of economy, it's more than 30...
the worst my car gets on my commute is about 35, average is about 43.5 (5.4L/100km) highest I've seen is 50.
(which is inline with the advertised economy, that's with a conventional auto, no GDi, and having better crash worthiness than a civic and being plush).
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Given that the entire tank is less than 12 gallons, I doubt that there's a few more gallons left on empty.
The only time that light lit up, I fuel up 43L of fuel in the 45L tank, so there was just over half a gallon.
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(Which is what the owner's manual says: "Driving with the Low Fuel Level warning light on or with the fuel level below �0 or E� can cause the engine to misfire and damage the catalytic converter.")
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It begins to prompt you at 1/8 tank (3 gallons left) to "refill fuel tank" on the gauge cluster, and much the light comes on and it means that the car's about to die...
Not all cars are like this, but a lot of the compact cars are.
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but generally we both agree, filling up that early it doesn't do much.
ok so 50 mpg. That's still over a gallon reserve. But it doesn't matter anyway for the reasons I explained.
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I think your manual is very sensible about it. When it gets to 'E' then you fill up. (Of course they being conservative , rightfully so, to allow for all kinds of variables like long steep hills etc).
When I was younger, stupider, and poorer, my tank was always empty.
The only time I experienced misfire from running low, was a 100m before I used the last drop and the engine stalled.
Still never had a pump go out.
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I don't understand the catalytic converter thing. Running rich is bad for the cat ... not lean.
Im unsure but some Hyundai-Kia engines have two catalytic convertors (WCC/UCC) with one of them being located in the exhaust manifold about 7-8 inches from the engine’s exhaust port.
I think the engineers are afraid of a lean mixture causing misfires that’d let air and fuel detonate in the manifold integrated cat and cause damage
(Hyundai-Kia cats create a lot of ceramic dust as they wear out (that wear rarely affects cat performance), perhaps on a worn upstream cat may get destroyed from detonations after its internals have been weakened due to wear)