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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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84
votes
11answers
92k 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 ...
77
votes
10answers
43k views

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 ...
61
votes
6answers
265k 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 ...
35
votes
11answers
11k views

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 ...
28
votes
6answers
10k 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 ...
28
votes
9answers
118k 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 ...
24
votes
5answers
139k 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 ...
24
votes
4answers
372k 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 ...
23
votes
4answers
9k views

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 ...
22
votes
1answer
26k 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 ...
21
votes
3answers
2k 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 ...
17
votes
2answers
302k 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 ...
17
votes
2answers
6k 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 ...
16
votes
13answers
252k 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 ...
16
votes
6answers
38k 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 ...
16
votes
6answers
44k 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 ...
16
votes
5answers
78k 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 ...
15
votes
4answers
12k 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 ...
14
votes
10answers
13k 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 ...
14
votes
6answers
27k 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
8answers
3k views

What causes a 20% difference in fuel economy between winter and summer?

I've been keeping track of the fuel my car, a Ford Fiesta Ecoboost 100 hp, uses since the day I got it. In the last three years I've owned it, I've noticed a large (>20%) difference in fuel ...
13
votes
3answers
32k 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
2answers
1k views

How to determine injector size for custom engine?

I've got a 2.5 L engine here for which I do not know the performance specs (yet), because it's customized. I need to select injectors for this build, but there seems to be only one equation on the ...
13
votes
2answers
14k 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
3answers
44k views

What's the meaning of a “lean” vs “rich” air fuel mixture

I'm learning about vacuum leaks on engine intakes and I'm hearing this terminology of lean air fuel mixture. I thought I heard of a rich mixture before too. What's a normal mixture referred to as? A ...
12
votes
3answers
14k 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
1answer
1k views

Do I need any special maintenance plan for a car only driven a every couple of weeks?

I work from home, so I seldom need to use my car. It's kind of nice that it can stay cleaner in winter, too. I could probably get away with almost never driving it winter, but I haven't prepped it ...
12
votes
1answer
73k views

What is seafoam? What does it do? How do you use it?

Mech's seem to get a real rubbery one about Seafoam. Is it just fuel additive, like something similar to Lucas Oil? Do I just pour it into my gas tank as a gas treatment? What will it do/help ...
12
votes
4answers
28k 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 ...
11
votes
5answers
6k 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 ...
11
votes
6answers
30k 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 ...
11
votes
2answers
1k 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?
11
votes
2answers
2k 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,...
11
votes
1answer
115 views

Occasional trouble idling

I have a 2004 Subaru Forester XS (manual transmission). A few times a month, the engine will not start or idle without feathering the accelerator. During normal driving, everything works fine until ...
11
votes
2answers
969 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 ...
10
votes
3answers
1k 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
2answers
6k 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 ...
10
votes
3answers
33k 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
1answer
2k views

Is it really not advisable to let your fuel tank get low on fuel?

I have frequently heard people blaming engine problems on letting the fuel in the fuel tank get too low, in so doing allowing sediment to be sucked into the fuel pump, which then causes a blockage. I ...
10
votes
3answers
4k views

Cleaning fuel injectors?

I took my car (2006 Honda Civic) to firestone to get an oil change and they told me I should get the fuel injectors cleaned. I was in an Advanced Discount Auto Parts store the other day and I noticed ...
10
votes
2answers
702 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
2answers
18k views

Power loss in truck - triage options?

I've asked at least one question about my specific situation earlier, but at this point, I'm looking for information on how to operate in triage mode, my primary goal is to get my truck working well ...
10
votes
1answer
7k 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
467 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
2answers
5k 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
282 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
2answers
21k 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 ...
9
votes
3answers
3k 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
2k 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
2answers
3k views

1999 Subaru Forester - bad acceleration, rough shifting

I have a 1999 Subaru Forester with an automatic transmission and a 2.5 Liter Motor. It has poor acceleration and rough shifting I started to notice 'hesitation' on take off. It just slowly appeared....