20 + Interview Questions in Fuel Supply System in Automobile Engineering Page 1 InterviewSolution

1.	What is the pressure differential causing fuel flow if the venturi depression is found to be 105 cm of water?(a) 10300.5 Pa(b) 20300.5 Pa(c) 50300.5 Pa(d) 60300.5 PaThe question was asked in an internship interview.This key question is from Petrol Engine Fuel System in section Fuel Supply System of Automobile Engineering
Answer» RIGHT option is (a) 10300.5 Pa To explain I would say: PRESSURE DIFFERENTIAL causing fuel flow = ΔPf, ρ = density of water, h = height of nozzle above the fuel level. ΔPf = Ghρ = 9.811.051000 = 10300.5 kg/m^2.

Discussion

2.	If petrol has a density of 800 kg/m^3 and the discharge nozzle is located 8 mm above the level of petrol in a float chamber. What is the pressure differential causing airflow?(a) 62.78 Pa(b) 42.78 Pa(c) 52.78 Pa(d) 72.78 PaThis question was addressed to me during an interview.Query is from Petrol Engine Fuel System topic in chapter Fuel Supply System of Automobile Engineering
Answer» The correct option is (a) 62.78 Pa To explain: When the fuel flow just starts ΔPf = 0 i.e. ΔPa – ghρf = 0. (ΔPf = pressure differential causing fuel flow, ΔPa = pressure differential causing airflow, h = HEIGHT of nozzle above the fuel LEVEL, ρf = density of fuel) ΔPa – 9.81(810^-3)*800 = 0 i.e. ΔPa = 62.78 Pa.

Discussion

3.	Which of the following is the most widely used fuel supply system?(a) Gravity system(b) Pressure system(c) Pump system(d) Vacuum systemThis question was posed to me in a national level competition.My question comes from Petrol Engine Fuel System topic in section Fuel Supply System of Automobile Engineering
Answer» Right answer is (c) Pump SYSTEM The best explanation: The most widely used FUEL supply system is the pump system. In this system, a STEEL pipe carries PETROL to the fuel pump which pumps into the float chamber through a flexible pipe.

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4.	Which of the following is the most accurate petrol injection system?(a) Manifold injection(b) Port injection(c) Throttle body injection(d) Direct injectionThe question was posed to me by my school principal while I was bunking the class.The question is from Petrol Engine Fuel System in chapter Fuel Supply System of Automobile Engineering
Answer» Right choice is (B) Port injection For explanation I would SAY: The most accurate petrol injection SYSTEM is port injection. In this system, the INJECTOR sprays the fuel into each intake port on the manifold side of the inlet VALVE.

Discussion

5.	What does the venturi in carburetor cause?(a) Increase of air velocity(b) A decrease in air velocity(c) A decrease in fuel flow(d) Decrease of manifold vacuumI got this question in class test.I would like to ask this question from Petrol Engine Fuel System in division Fuel Supply System of Automobile Engineering
Answer» RIGHT ANSWER is (a) Increase of air velocity For explanation: The venturi in carburetor causes an increase in air velocity. The MAIN function of the carburetor are to keep a reserve of FUEL at a constant head.

Discussion

6.	Where is the lean air-fuel mixture needed?(a) During starting(b) During idling(c) During acceleration(d) During cruisingThis question was posed to me in an internship interview.My enquiry is from Petrol Engine Fuel System in chapter Fuel Supply System of Automobile Engineering
Answer» Correct ANSWER is (d) During cruising Explanation: The LEAN air-fuel MIXTURE is needed during cruising. In this range, it is desirable that the carburetor provides the engine with the best fuel ECONOMY.

Discussion

7.	When is the choke used in the engine?(a) When the vehicle is idling(b) When the vehicle is accelerating(c) When the engine is cold(d) When the engine is hotI had been asked this question by my college director while I was bunking the class.This is a very interesting question from Petrol Engine Fuel System in division Fuel Supply System of Automobile Engineering
Answer» The correct option is (C) When the ENGINE is cold To elaborate: The choke is USED when the engine is cold. The choke is a butterfly valve located between the entrance to the CARBURETOR and the venturi throat.

Discussion

8.	In multiple venturi carburetors, the main jet discharges the fuel in a downward direction into the primary venturi against the upward air stream.(a) True(b) FalseThe question was posed to me in an interview.This is a very interesting question from Carburettors topic in division Fuel Supply System of Automobile Engineering
Answer» Correct choice is (b) False Explanation: In multiple VENTURI carburetors, the main JET discharges the fuel in an upward direction into the primary venturi against the downward air STREAM. The fuel ATOMIZED by the air stream.

Discussion

9.	A four-stroke gasoline engine of 1.9-liter capacity is to develop maximum power at 6000 revolutions per minute. The volumetric efficiency is 80%. What is the actual volume of air sucked per second?(a) 0.053 m^3/s(b) 0.076 m^3/s(c) 0.046 m^3/s(d) 0.089 m^3/sI had been asked this question in unit test.I would like to ask this question from Carburettors in chapter Fuel Supply System of Automobile Engineering
Answer» Right answer is (b) 0.076 m^3/s To explain I would SAY: Actual volume of air sucked PER second = EFFICIENCY * volume of engine (revolution per minute / 2) (1 / 60) = 0.8 * 1.9 * 10^-3* (6000 / 2) * (1 /60) = 0.076 m^3/s.

Discussion

10.	Which of the following is not the part of a carburetor?(a) Float chamber(b) Choke and throttle(c) Fuel strainer(d) Auxiliary valveThis question was posed to me in homework.I'm obligated to ask this question of Carburettors topic in chapter Fuel Supply System of Automobile Engineering
Answer» The correct CHOICE is (d) Auxiliary valve The explanation is: A carburetor CONSISTS of fuel strainer, float chamber, choke, throttle, main fuel metering, and idling NOZZLES. The auxiliary valve is ONE of the compensating DEVICES.

Discussion

11.	Which type of carburetor is a constant vacuum carburetor?(a) Zenith(b) Solex(c) S. U.(d) CarterI have been asked this question during an interview.I'd like to ask this question from Carburettors in division Fuel Supply System of Automobile Engineering
Answer» Right ANSWER is (c) S. U. Best explanation: S. U. CARBURETOR is a constant vacuum carburetor. SOLEX, Carter, and Zenith are a type of constant choke carburetor.

Discussion

12.	To burn 1 kg of octane completely, how much amount of air is required?(a) 14.12 kg(b) 15.12 kg(c) 16.12 kg(d) 10.12 kgI got this question in exam.This intriguing question originated from Carburettors in chapter Fuel Supply System of Automobile Engineering
Answer» The correct choice is (b) 15.12 kg To elaborate: Complete COMBUSTION MEANS all CARBON in the fuel is converted to CO2 and all hydrogen to H2O. To burn one kg of octane (C8H18) COMPLETELY 15.12 kg of air is REQUIRED. Hence the correct Air Fuel ratio is 15.12: 1. Sometimes, it is approximated to 15: 1.

Discussion

13.	When does the simple carburetor supplies rich mixture?(a) Idling(b) Cruising(c) Accelerating(d) StartingThe question was posed to me during an online interview.My question is taken from Carburettors in portion Fuel Supply System of Automobile Engineering
Answer» The CORRECT answer is (c) ACCELERATING The EXPLANATION is: The SIMPLE carburetor supplies the rich mixture during accelerating. During acceleration, the engine REQUIRES more amount of fuel to get the high speed of the vehicle due to which there is a requirement of the rich mixture.

Discussion

14.	What is the stoichiometric air-fuel ratio of diesel?(a) 50: 1(b) 14.7:1(c) 25: 1(d) 14.5: 1I got this question in an online interview.Question is from Carburettors topic in section Fuel Supply System of Automobile Engineering
Answer» CORRECT OPTION is (d) 14.5: 1 Explanation: The stoichiometric air-fuel RATIO of diesel is 14.5: 1. The stoichiometric air-fuel ratio of petrol is 14.7: 1. The mixture which contains less air than the stoichiometric requirement is called a RICH mixture.

Discussion

15.	Where does the power for mechanical fuel pump come from?(a) Camshaft(b) Crankshaft(c) Distributor shaft(d) Propeller shaftThis question was posed to me in my homework.My query is from Petrol Engine Fuel System in division Fuel Supply System of Automobile Engineering
Answer» The correct option is (a) CAMSHAFT The explanation: The power for mechanical fuel PUMP COMES from the camshaft by means of an eccentric CAM.

Discussion

16.	The principle of compensating jet device is to make the mixture leaner as the throttle opens progressively.(a) True(b) FalseI have been asked this question in a job interview.Asked question is from Carburettors in section Fuel Supply System of Automobile Engineering
Answer» The CORRECT ANSWER is (a) True The EXPLANATION: Most of the times the compensating JET is incorporated in the carburetor with the MAIN jet. The compensating jet makes the mixture leaner as the main jet makes the mixture richer.

Discussion

17.	What is the value of the rate of flow of fuel if the coefficient discharge of fuel is 0.75, area of the jet is 0.885 mm^2, density of the fuel is 780 kg/m^3, and pressure differential causing fuel flow is 15000 Pa?(a) 3.21 g/s(b) 4.21 g/s(c) 5.21 g/s(d) 6.21 g/sThis question was posed to me in an interview.This interesting question is from Petrol Engine Fuel System in portion Fuel Supply System of Automobile Engineering
Answer» The CORRECT option is (a) 3.21 g/s To elaborate: Pressure differential causing fuel FLOW = ΔP = 15000 PA, coefficient of discharge = Cf = 0.75, density of the fuel = ρ = 780 kg/m^3, and AREA of the jet = A = 0.885 mm^2. The rate of flow of fuel = Wf = A* Cf\(\sqrt{2\rho\Delta P}\) = 0.8850.7510^-6\(\sqrt{278015000}\) = 3.21*10^-3 kg/s = 3.21g/s.

Discussion

18.	Why is the small hole provided in the pump body?(a) A vent for the oil(b) A vent for water(c) A vent for air(d) A vent for the fuelI got this question in examination.My doubt stems from Petrol Engine Fuel System topic in portion Fuel Supply System of Automobile Engineering
Answer» Right CHOICE is (C) A vent for air For explanation I WOULD SAY: The small HOLE is provided as a vent for air in the pump body. This is an escape for excess air in the pump. So that pump does not get overloaded.

Discussion

19.	Which type of carburetor the Solex is?(a) Constant choke carburetor(b) Constant vacuum carburetor(c) Multiple venturi carburetors(d) Multijet carburetorThe question was asked in my homework.My doubt stems from Carburettors in portion Fuel Supply System of Automobile Engineering
Answer» The CORRECT CHOICE is (a) CONSTANT CHOKE carburetor To explain: Solex carburetor is a constant vacuum carburetor. Other constant vacuum carburetors are ZENITH and Carter. S. U. carburetor is a type of constant choke carburetor.

Discussion

20.	What is the purpose of the venturi in the carburetor?(a) To decrease the fuel flow(b) To increase the manifold vacuum(c) To increase the air velocity(d) To decrease the air velocityI had been asked this question in an interview for internship.This interesting question is from Carburettors topic in chapter Fuel Supply System of Automobile Engineering
Answer» Correct CHOICE is (d) To decrease the air velocity Easy explanation: The purpose of the VENTURI in the carburetor is to increase the air velocity. The venturi in carburetors is used to measure AIRFLOW in an ENGINE.

Discussion

Explore topic-wise InterviewSolutions in .

Where is the lean air-fuel mixture needed?(a) During starting(b) During idling(c) During acceleration(d) During cruisingThis question was posed to me in an internship interview.My enquiry is from Petrol Engine Fuel System in chapter Fuel Supply System of Automobile Engineering

Which of the following is not the part of a carburetor?(a) Float chamber(b) Choke and throttle(c) Fuel strainer(d) Auxiliary valveThis question was posed to me in homework.I'm obligated to ask this question of Carburettors topic in chapter Fuel Supply System of Automobile Engineering

Which type of carburetor is a constant vacuum carburetor?(a) Zenith(b) Solex(c) S. U.(d) CarterI have been asked this question during an interview.I'd like to ask this question from Carburettors in division Fuel Supply System of Automobile Engineering

To burn 1 kg of octane completely, how much amount of air is required?(a) 14.12 kg(b) 15.12 kg(c) 16.12 kg(d) 10.12 kgI got this question in exam.This intriguing question originated from Carburettors in chapter Fuel Supply System of Automobile Engineering

When does the simple carburetor supplies rich mixture?(a) Idling(b) Cruising(c) Accelerating(d) StartingThe question was posed to me during an online interview.My question is taken from Carburettors in portion Fuel Supply System of Automobile Engineering

What is the stoichiometric air-fuel ratio of diesel?(a) 50: 1(b) 14.7:1(c) 25: 1(d) 14.5: 1I got this question in an online interview.Question is from Carburettors topic in section Fuel Supply System of Automobile Engineering

Where does the power for mechanical fuel pump come from?(a) Camshaft(b) Crankshaft(c) Distributor shaft(d) Propeller shaftThis question was posed to me in my homework.My query is from Petrol Engine Fuel System in division Fuel Supply System of Automobile Engineering

The principle of compensating jet device is to make the mixture leaner as the throttle opens progressively.(a) True(b) FalseI have been asked this question in a job interview.Asked question is from Carburettors in section Fuel Supply System of Automobile Engineering

Why is the small hole provided in the pump body?(a) A vent for the oil(b) A vent for water(c) A vent for air(d) A vent for the fuelI got this question in examination.My doubt stems from Petrol Engine Fuel System topic in portion Fuel Supply System of Automobile Engineering

Which type of carburetor the Solex is?(a) Constant choke carburetor(b) Constant vacuum carburetor(c) Multiple venturi carburetors(d) Multijet carburetorThe question was asked in my homework.My doubt stems from Carburettors in portion Fuel Supply System of Automobile Engineering