Motor Vehicle Maintenance & Repair Stack Exchange
Motor Vehicle Maintenance & Repair Stack Exchange

Questions tagged [fuel-system]

Fuel system covers the components of a car responsible for fuel delivery; tanks, pumps, filters, pipes. Questions on carburettors and injection systems have individual tags

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Does the amount of fuel in the tank matter?

As long as there is some fuel in the tank, does the fuel level matter? In other words, is it advisable to make sure the tank is mostly full most of the time, or is this just silly? In other words, are there valid reasons why you should avoid running…
Ola Eldøy
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What are the benefits of premium (high octane) petrol?

Here in the UK it's common for petrol (gas) stations to offer both regular and "premium" unleaded petrol. The premium stuff is (naturally) more expensive, and I've often wondered what the actual difference is. Would I need to fill up with premium…
Simon Whitaker
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How long does it take for gas to go bad?

Approximately how long does it take for unleaded gasoline in the tank and fuel lines to become unusable in a car that is not being used? What causes this, and what can be done to prevent or remedy the issue? UPDATE: The car that prompted this…
Iszi
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What is in fossil fuels that we can't mass produce?

Since fuel is made up of different molecule chains, my question is what is the reason we cannot create the same molecule structure and be able to reproduce the same structure in a lab so we don't have to run out? I understand there's way more to…
LostPecti
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Will higher octane fuel improve gas mileage?

I've heard from some people that high octane fuel will increase gas mileage. Around here, we have the basic unleaded(87), mid-grade(89), and premium(93 or 91). I've been using the basic 87 unleaded forever because it was the cheapest. Also, in my…
Earlz
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Do cars consume less fuel when in Neutral?

Imagine we're going down a hill and we're driving a manual car. There are two situations: If I put my car in neutral it will go downhill without any need for the injector to squirt fuel into the system, just enough fuel for the engine to idle. I…
Andrew Ravus
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Why should the fuel petcock valve be turned to “Off” position when not using the vehicle?

It’s mentioned in the user manual of my motorbike, that when not using the vehicle, I should turn the petrol tap (the one that has three positions “On”, “Off” and “Reserve”) to “Off” position. I don’t understand why that’s necessary (and I need to…
Nav
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Symptoms of Lean or Rich carb settings on a motorcycle

I have a 1981 Yamaha XS650. I recently put in K&N stock replacement filter (ie, they are in the airbox and conform to the size of the original), however they may be leading to a leaner mixture because they purportedly let through more air. I want to…
user460
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Small amount of wrong fuel type put in the tank

The guy who works at a gas station was filling up for brief moment wrong fuel type in my car until he realized what he did. I own Citroen Xsara 1.9d, make year 2000. Before filling the tank which is 60l capacity, I had about half tank full. The pump…
tolkinski
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LTFT and STFT values are off and don't make sense

Car is a 2015 BMW M5 and it has an aftermarket CAI and a catback (slip on) exhaust. No other performance mods or tunes. About 6-7 months ago, I bought a Kiwi OBD-II reader, simply out of curiosity as I am a computer guy and a geek and was curious…
DerStig
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Does a carburettor engine apply fuel at high speeds when the pedal is no longer depressed?

There's a question that is pretty similar to this one except the existing question satisfies EFI engines. EFI question Let's say I roll down a hill at a considerable speed I let go of the gas. Say my revs are 3000. While going down the hill my revs…
EChan42
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What does Honda's 'Econ' button do? Does it truly improve fuel efficiency?

I recently bought a Honda Civic that had this in the car: I have no idea what it does, and how it's supposed to help. Even Honda's website is ambiguous, just using a lot of fuzzy words to describe what it does. From the website: Econ Button and…
yuritsuki
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What happens if you put the wrong kind of gas in your car?

I (like most people) just use regular unleaded gas in my car and always have. But once I accidentally put in the premium kind, mixing it with the unleaded that was already there, and I thought for sure my car was going to explode or something, but…
temporary_user_name
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Can I use lower octane fuel at high elevation?

Here in Colorado, gas stations sell "regular" gasoline which is rated at 85 octane ((M+R)/2). In most of the rest of the US, 87 octane is the lowest grade available. (As noted previously, higher octane fuel can withstand higher compression without…
Nate Eldredge
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how to optimize fuel consumption by changing the rear differential ratio?

Is it possible to improve the fuel consumption (decrease it) in my van by changing the rear differential ratio? I would like to optimize it for low-speed driving about 40 km/h (25 mph). Is it true that the rear differential ratio is optimized for a…
ria
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