Fuels & Fuel Systems:
Before working on fuel systems or with fuels, Safety must come first:
- Never expose petrol to a naked flame, spark, or heat.
- Always disconnect the negative terminal of the battery before performing any task that would release petrol from any part of the system.
- Always use a container to catch any dripping petrol.
- Wipe petrol spills away immediately no matter how minor.
- When extra lighting is required always use a flash light rather than a lead light. Petrol split onto a hot bulb may cause the bulb to explode and ignite the fuel.
- Never attempt to weld a petrol tank.
- Always store fuel (no more than 5 liters) in a sealed marked container.
- Always keep a B class fire extinguisher nearby.
- Use warning signs to ensure other personnel are aware of petrol and fume dangers when working on the fuel system.
- Avoid skin contact with petrol and other automotive fuels.
- Be careful. Play by the rules.
Vacuum Pressure Testing:
When there is no throttle & the engine sits at idle, there is greater vacuum & when there is throttle there is no vacuum at all.
- Regulator/ Pressure Regulator sits on the end of the fuel rail. Vacuum pipe connects to the manifold cover.
- No throttle the regulator opens & the vacuum starts sucking fuel back through to the fuel tank.
- With lots of throttle or just any throttle the Regulator shuts & vacuuming stops.
- Pressure in the fuel rail becomes greater allowing more pressure to spray fuel into the intake manifold.
When testing the pressure - No Load & Load:
- No load testing the Vacuum hose pipe is to be left on & sits at idle.
- Load testing the Vacuum hose pipe is to be taken off & sits at idle.
Our Results:
- No Load - 280 KPA - 40 PSI.
- No Load Manifold - 11 PSI - 75 KPA.
- Load - 350 KPA - 50 PSI
- Load Manifold - 0 PSI
Purpose of Vacuum Testing:
Is to determine whether there is enough Pressure to move the diaphragm within the regulator so that the fuel is able to be sucked back through to the petrol tank.Also to determine that there is enough pressure build up in the fuel rail so that the injectors can spray into the intake manifold.
- Here we have the fuel tank showing the fuel feed line & also the excess fuel return line.
- (pic on left) shows the fuel filter
- (pic on right) shows the fuel line running to the fuel filter
- Fuel filter & fuel line
- (pic on the left) From the fuel filter the fuel line continues to runs up to the fuel rail.
- (pic on right) is the fuel line connected to the fuel rail.
- (pic above) Is showing the fuel rail, Intake manifold, Injectors & on the end of the fuel rail the fuel pressure regulator.
- (pic on left) Fuel pressure regulator, end of fuel rail.
- (pic on right) Regulator & vacuum line.
Vacuum:
- · Pressure less than atmosphere
- · Less vacuum = more pressure
- · Lots vacuum = less pressure
- · 100 KPA = 1 atmosphere pressure
- · Open the throttle more pressure less vacuum
