EFI On Car Testing
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| Toyota 4A-FE that was used to conduct the first tests |
Today I began The on car EFI testing the tests that I did were for Fuel Pressure and fuel flow.
Checking Fuel Pump
This Test involved inspecting various fuel pressures under different operating conditions these conditions are: fuel pressure at idle, the maximum pressure and the residual pressure.
Idle Pressure: Test involved watching the fuel pressure gauge when car was running at idle this showed a pressure of 265 kPa which was within manufactures specs of 265kPa - 304kPa.
Maximum fuel pressure: this test involved removing the vacuum hose from the fuel pressure regulator and then blocking it with your finger and reading what the fuel pressure is showing. There was a reading of 44PSI on the gauge and manufactures specs were 38-44PSI so it was within specs.
Residual Pressure: This test was done with the engine switched off and pressure read on gauge after 5 minutes to see how it was holding this showed a pressure of 250kPa and manufactures specs were 206-255kPa.
If when tested the fuel pressure was to high this would cause the injectors to put too much fuel into the combustion chambers and would cause the engine to run rich causing poor fuel economy, and fouled spark plugs.
If the fuel pressure was too low this would cause a rough idle, poor engine performance and misfiring.This could be to do with the fuel filter being clogged and would need replacing.
If there was no fuel pressure at all this could mean pump is malfunctioning or needs replacing.
Fuel Flow
This test involves testing how well the fuel pump is delivering fuel to the injectors and was done by first removing the fuel pressure from fuel lines by removing the fuel pressure relay and then cranking engine until the pressure has dropped to zero. Then disconnecting the fuel line and running it into a measuring container. Then turning the ignition on and running the pump for 15 seconds and then recording the results.
The tested engine had a fuel flow of 3.6L per minute. which was within specification of 2.5 - 3.5L per minute.
The amount of fuel was slightly above required but was not a major problem as it is better to have more fuel flowing. If not enough fuel was being delivered (running Lean) this would cause the vehicle to be down on power and cause surging or slow response on acceleration.
Maximum fuel pressure: this test involved removing the vacuum hose from the fuel pressure regulator and then blocking it with your finger and reading what the fuel pressure is showing. There was a reading of 44PSI on the gauge and manufactures specs were 38-44PSI so it was within specs.
Residual Pressure: This test was done with the engine switched off and pressure read on gauge after 5 minutes to see how it was holding this showed a pressure of 250kPa and manufactures specs were 206-255kPa.
If when tested the fuel pressure was to high this would cause the injectors to put too much fuel into the combustion chambers and would cause the engine to run rich causing poor fuel economy, and fouled spark plugs.
If the fuel pressure was too low this would cause a rough idle, poor engine performance and misfiring.This could be to do with the fuel filter being clogged and would need replacing.
If there was no fuel pressure at all this could mean pump is malfunctioning or needs replacing.
Fuel Flow
This test involves testing how well the fuel pump is delivering fuel to the injectors and was done by first removing the fuel pressure from fuel lines by removing the fuel pressure relay and then cranking engine until the pressure has dropped to zero. Then disconnecting the fuel line and running it into a measuring container. Then turning the ignition on and running the pump for 15 seconds and then recording the results.
The tested engine had a fuel flow of 3.6L per minute. which was within specification of 2.5 - 3.5L per minute.
The amount of fuel was slightly above required but was not a major problem as it is better to have more fuel flowing. If not enough fuel was being delivered (running Lean) this would cause the vehicle to be down on power and cause surging or slow response on acceleration.
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