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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9answers
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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 ...
64
votes
9answers
44k views

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 ...
45
votes
5answers
123k views

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 ...
26
votes
6answers
6k views

Do cars consume less fuel when in Neutral? [duplicate]

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 ...
23
votes
8answers
67k views

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 ...
21
votes
3answers
1k views

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 ...
19
votes
1answer
1k views

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 ...
18
votes
5answers
57k views

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 ...
15
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4answers
75k views

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 ...
14
votes
6answers
26k views

How to properly dispose of old fuel?

I have some old 2 stroke mixed gas I need to get rid of. This could also apply to old fuel removed from a sitting car or any vehicle for that matter. What is the proper way to dispose of this? Are ...
14
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5answers
2k views

How exactly does running fuel-lean increase the temperature of ignition?

I learned in this question that running an engine fuel-lean will increase the temperature of ignition, among other things such as causing problems with the catalytic converter. I have no idea how or ...
14
votes
6answers
14k views

How to improve fuel economy in high-mileage car?

I'm driving an 2003 Acura TL 3.2 with 177K miles on it. I bought the car with 110K miles on it. It seems to me that the car is not getting the same fuel economy that it did when I acquired it. I ...
13
votes
9answers
11k views

Diesel vs Petrol motorcars. Pro's and cons?

I realize this may be a silly question to those of you on here who are proper petrol-heads and this may even be a repeat question, but I could not find anything on it on here, so here goes: What are ...
13
votes
2answers
9k views

I accidentally fueled my car with E10 (10% ethanol). What should I do next?

So I have a 2000 Honda Civic LX that is around 130k miles now. In Las Vegas, I put E10 (I hadn't known what it was before this...), and had to get it fixed. The engine light had started blinking and ...
13
votes
1answer
4k views

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 ...
13
votes
2answers
377 views

Why do diesel fuel lines have to be bled?

Background I've had a couple of situations with diesels. One in particular where I swapped a Ford F350 Powerstroke 7.8 transmission. When I was done. The truck wouldn't start. It was a painful ...
12
votes
4answers
5k views

Difference between high octane and low octane?

What is the difference between high octane and low octane fuel? I'm not asking if one is better than the other for my vehicle, specifically, but rather what occurs differently both scientifically and ...
12
votes
3answers
9k views

Is high octane fuel a requirement for high-compression engines?

I own and use a 2005 Chrysler Crossfire SRT-6 as my daily commuter vehicle. I'm not interested in trying to eek out a few extra miles on a tank, I want to keep the vehicle and its engine running as ...
12
votes
2answers
185 views

Motorcycle Four Body Carburetor Synchronization Balancing

I would like to adjust four-body carbs by myself, in order to avoid spent money every time. What are the basic rules, tools and secrets of synchronizing multiple carburetor bodies?
12
votes
4answers
5k views

Gasoline is dripping out of a rubber tube outputting on the bottom of my motorcycle - is this normal, or is it a problem?

What bike? A BMW 650, 1996 model. What's the problem? I noticed a slow, but steady, drip of gasoline from one of two rubber tubes that output to the bottom of the bike. I think the other rubber ...
12
votes
2answers
128k views

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 ...
11
votes
13answers
97k views

Is the ECON button just a placebo?

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 ...
11
votes
2answers
396 views

2001 Infiniti QX4 rough idle - leaking fuel damper vacuum port

I have a bit of an involved problem, so I’ll break it down a bit and try to provide as much detail as possible. My main problem: I have a rough idle on my 2001 Infiniti QX4. It’s not extremely rough,...
10
votes
3answers
420 views

Direct Injection Injectors - How do they prevent blow back into the fuel system?

So I imagine a direct injection injector as a fuel injector squirting fuel directly into the combustion chamber. The amount of pressure in the combustion chamber would seem to be enough to push the ...
10
votes
6answers
11k views

Why does a diesel sound like that?

My car is in the shop for a repair, and they gave me a loaner. It's a Chevy Cruze Diesel. Sitting on the driveway, my wife said, "It sounds like a truck". It does. So what exactly it is about ...
10
votes
3answers
20k views

How do I safely siphon gas from a tank?

Our 2003 Windstar was recently totaled in an accident (everybody's ok). This happened the day after we filled the tank. Before we hand over the car to the insurance, we'd like to get the fuel out of ...
10
votes
2answers
340 views

Can't start a Kawasaki GPX 750

I'm in the process of getting my 1986 Kawasaki GPX 750 back in running condition. The bike was sitting in the garage for two years. In this period it wasn't started even once. Two years ago the engine ...
10
votes
1answer
384 views

Leaking Fuel Injector Seal

I recently had to remove the fuel injectors and fuel rail to clean out the EGR ports on my Honda Accord. The EGR port was all clogged up with carbon build up. I replaced all the old o-rings, cushion ...
10
votes
1answer
163 views

Sharp whining noise coming from rear of the car

In my Toyota Vitz 2007, I hear a sharp whining noise coming from the rear of the vehicle. This noise does not always happen. When the vehicle is started, the noise is not there. But after driving for ...
9
votes
4answers
2k views

How critical is it to match the stock fuel pressure regulator pressure when replacing it?

My fuel pressure regulator needs replacing, however the original part from the manufacturer is outrageously expensive. While looking for less financially painful alternatives I've seen much cheaper ...
9
votes
2answers
155 views

Is it bad on your fuel pump to have your tank run low? [duplicate]

Ive always been taught it was bad on your fuel pump to run your vehicle tank close to dry as it would damage the fuel pump but Ive never seen any validation to support this statement. So will running ...
9
votes
1answer
52 views

Lada Niva 1700 Carburetor Model

The compression is good and does not burn excessive oil .Fuel consumption has dropped from 8 kilometers per liter to 5.7 kilometers per liter.Same driving cycle same location. What should I look for?
9
votes
3answers
2k views

What are the causes of fluctuating intake manifold vacuum

I have a 2005 Honda CBR600 F4i which suffers from occasional hesitation at low rpm when accelerating. I also get occasional fault codes from the ECU indicating a vacuum leak. Today I connected a ...
9
votes
1answer
147 views

What is the yellow precipitate in my outboard's carburetor?

I've got a 2008 Tohatsu 9.8 HP four stroke outboard. My low speed jet keeps getting fouled and on several occasions, I've found yellow almost crystalline "growths" for lack of a better word inside ...
9
votes
1answer
95 views

Ford Tractor 5600

This is a older tractor. My question relates to the fuel system. The older fuel injectors don't have any external seals? All of them seat and 3 don't leak but one does. I was looking for a seal but ...
9
votes
3answers
26k views

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 ...
8
votes
2answers
574 views

Why is the effect of a bad fuel pump more noticable at higher speeds?

I get that the main effect of a bad fuel pump is that the engine will cut out at higher speeds, and that this is often not easily noticeable until that happens because there are little or no prior ...
8
votes
2answers
515 views

Why is the engine on my Royal Enfield Classic 350 shutting down?

After travelling 7-8km on my Royal Enfield Classic 350, the bike acts as if the fuel is finished & the engine shuts down, but it starts again when I pull the accelerator. What could cause this ...
8
votes
1answer
64 views

What is the “Activated Carbon Cannister”?

Why do I have an "Activated Carbon Cannister" in my unleaded/petrol car? What is it's purpose? How does it work? Do I need to do anything to maintain it? I would like a general answer, but my car ...
8
votes
3answers
4k views

Should I run my generator dry in preparation for storage?

I think this is on-topic after reading the FAQ, so I figured I'd go ahead and ask. I gave my gas generator its scheduled 3-month interval "workout" last night, and after letting it run for about 30 ...
8
votes
2answers
91 views

Two Fuel Pumps died

Already having replaced 2 fuel pumps, both died. Seems to have a problem in somewhere (alternator, battery, electricity) or I have no luck for fuel pumps. The last one, last 6 months, before died ...
8
votes
2answers
9k views

Test Gasoline for Water Content

I live in a small town, and the Gas station there has a bad reputation for gas quality. With rumors like peoples gas tanks freezing solid and such. Is there a quick, safe, cheap way to test for ...
8
votes
5answers
14k views

Doing my own fuel induction service - how to, and how difficult?

I was recommended to get a fuel induction service for a 2002 V4 Camry, and am considering doing it MYSELF. The reasons for considering this are: My car idles a bit rough, especially when the AC is ...
8
votes
1answer
96 views

Suzuki 2004 sv650s wiring

I got a 2004 sv650s Suzuki when I turn the key on the fuel pump does not come on and the CHECK light comes on on the dash. All the lights come on and the starter button does not work.All the fuses are ...
8
votes
4answers
78 views

Is there something I can use to replace a fuel gauge sender float?

The little ball that's attached to the fuel gauge sender in my car has a hole in it meaning that the fuel gauge isn't working. It is not possible to buy a replacement float - the whole sender unit ...
8
votes
1answer
791 views

how can I measure the amount of fuel injected into a diesel engine in real time in a purely mechanic pre-OBD vehicle?

This is a Mercedes-Benz 308D van, year 1992, model 602.316. Pre-OBD, no electronics of any sort, everything is purely mechanical. I would like to retrofit a system which would measure the precise ...
8
votes
2answers
73 views

Ford Expedition Eddie Bauer 4.6 V8 2003 automatic rpm goes high

When driving, sometimes when I want stop the vehicle, I go to press the brakes, but that time engine rpm goes high, keeping brakes pressed hard, after 5 second engine becomes normal. It goes high when ...
7
votes
2answers
658 views

What are all the different types of fluid in a car and a short summary of their use?

A fluid is defined as anything that flows, hence for our purposes a gas or a liquid. I know that there is fuel, engine oil, engine coolant and brake fluid. Also air is normally taken in through a ...
7
votes
3answers
8k views

Why does my gas not fill all the way?

Same as the title. I have filled twice, different stations, both fill to just over 3/4 and stop. I am not sure if this is the gauge or something with whatever magic tells the pump to stop. Is there ...
7
votes
4answers
2k views

Subsitute for Leaded Gas

I have an old '73 240-Z that I am fixing up in class. Once I get it running, will I need to add something to the gas? I know that old cars ran on leaded fuel, the lead lubricating the parts as it ...