Here I provide clear testing instructions.
Each system is supported by several sub systems.
Every component has a large role to play in the overall functioning as all systems depend on each other.
In case of fuel injection system, one of the most important parts is a fuel pump relay.
A failure of this part can cripple your car's functioning. In case of any fuel injection problems, it is customary to run a test on the relay, to determine if the source of the problem is that component.
What role does a fuel pump exactly play in the overall functioning of a car's fuel injection system? The fuel pump relay switches the fuel pump on and off.
All the vital systems of a car are controlled by the 'Engine Control Unit (ECU)', which monitors and executes all of its functions.
The ECU controls fuel pump, via the relay.
It is usually packed in a plastic casing and attached to the ignition system. It is usually located near the steering column, on the firewall.
It is basically like a small transformer system which works on the principle of magnetic induction.
For the engine cycle to begin, it's important that it is supplied with the right amount of fuel, at the right pressure.
For that, the fuel pump needs to be in working condition.
When there are problems with the relay, the fuel pump cannot function, leading to major car starting problems.
The relay comes into the picture twice, during operation of a fuel pump. At the very start of the engine cycle, it engages with the fuel pump to switch it on and later it disengages
after the pump begins operation.
Later the power required for functioning of the pump is usually supplied by oil pressure sending unit.
The relay is again switched on when the pump needs to be powered off.
So it is vital that the relay stays functional if you want the car ignition to be smooth.
Bad Relay Symptoms
So one of the prime symptoms is car starting problem.
Other than that, a delayed triggering of the engine may also indicate a bad relay.
Your fuel pump problems may actually be relay problems.
However, to isolate a badly functioning relay as the cause of car starting problems, you have to run a test.
You will need a ohmmeter for testing the relay.
Also needed, will be a circuit diagram of the relay if you get one.
The diagram is mostly printed in the relay itself. Firstly, locate the relay using the car reference manual.
Detach the relay and remove it from its casing.
All you have to do throughout the whole test is check for continuity and resistance between terminals.
There are four main terminals to check.
These include two power terminals and two control terminals.
Set the ohmmeter on its lowest resistance value.
Connect one of the ohmmeter leads with the first power terminal and second with the
If you find the resistance to be anything less than infinite, then the relay has undoubtedly shorted and it needs a replacement.
Next get hold of jumper wires and connect one from the positive terminal of the car battery to the positive control terminal.
Also connect another jumper cable from the negative of car battery terminal to ground.
If you hear the relay clicking as soon as you make the ground connection, it is in working condition.
Lastly check the continuity and resistance between the power and control terminals.
The resistance between them should be a few ohms.
If it is infinite, then you need to go for a relay replacement.
All you need is a ohmmeter to check voltage values and continuity.
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