WS4

First locate a fire extinguisher close by incase of an accident

There are several different ways to relieve the pressure before installing a pressure gauge , I personaly prefere this method myself ... Remove fuel pump relay then start engine till it run out of fuel and stops then to double check crank the engine to make sure no fuel is left in the fuel lines ... This is a very tidy , quick and not messy and also not dangrous to get rid of pressure in fuel lines .

Hook up the fuel prssure gauge , turn on the car briefly and stop to check for any fuel leaks. we didnt have any fuel leaks so we move to the next stage ...

Fuel pressure with key on and engine off was 284 Kpa.

After turn on the engine for a couple of minutes and the pressure was 260 Kpa.

Also with the engine running clamp the fuel return line to record maximum pressure 490 Kpa.

To similuate wide open throttle we disconnected vacuum line going to fuel pressure regulator 310 Kpa.

To check residual or rest pressure we turned off the engine and watched fuel pressure for 5 minutes 250 Kpa.

To check the flow of fuel in the fuel lines and to make sure enough fuel is getting to our injectors 2.2 L per minute and also to check if it is within manufacturer's specification because too low will cause a lean combustion and too much would make it run rich .

Now follow the same step as the top to get rid of fuel line pressure so we can disconnect our gauges and put the vacuum lines and fuel lines back where they belong . double check for leaks and make sure the vehicle is safe and runs fine.

Symptoms :

Low fuel pressure :

This will cause the engine to run rough and cause it to misfire due to lean mixture and increase emissions of HC.

Low fuel flow :

This could be caused by a blockage in the line eg. fuel filter blocked , this will cause the vehicle to have a poor performance specially under high loads or quick throttle response is poor also as the injector runs out of fuel to inject in to the cylinder

High fuel pressure :

This would cause black smoke out of the vehicle exhaust which indicates rich mixture and high HC (unburnt fuel) to enter the atmosphiere ... engine would run rough at idle. it also can be caused by faulty fuel pressure regulator .

Faulty fuel pressure regulator :

This will also result in black unburnt fuel to come out of the exhaust and very rich air/ fuel mixture . Bad fuel economy , high HC emissions . it also can damage the cat convertor and O2 sensor if this problems carries on for a long period .