A thread a few weeks back about how to test cylinder compression prompted me to take a few piccies this afternoon. The way I do it.... is to disconnect the main relay at the ballast resistor (which means the fuel pump and d jet injection is not powered), and disconnect the hot side the coil (which means no HT sparks flying around), and then I connect a jumper wire to the starter solenoid, so I can turn the engine over whilst watching the compression tester in the engine bay. There are other ways to do this, I think using the orange test connector.
On my d jet car the main relay gets a "run" signal from a connection on the ballast resistor. Other cars may differ I guess, but it's important to ensure no fuel is getting into the engine as it will affect the test results and will wash the cylinder bores. Also possible to disconnect the fuel pump at the relay under the rear right seat.
First photo shows a screwdriver in place to hold the throttle wide open and a jump lead connected to the + battery terminal. The cardboard box is insulation to keep that unfused power from causing problems
Second photo shows connection to main relay and power to coil disconnected
Third photo shows washer bottle and HT leads out of the way. All 6 plugs are out too.
Fourth photo tries to show the jumper wire attached to the starter solenoid. When you touch this to the jump lead, the solenoid engages the starter and turns the engine over
On my d jet car the main relay gets a "run" signal from a connection on the ballast resistor. Other cars may differ I guess, but it's important to ensure no fuel is getting into the engine as it will affect the test results and will wash the cylinder bores. Also possible to disconnect the fuel pump at the relay under the rear right seat.
First photo shows a screwdriver in place to hold the throttle wide open and a jump lead connected to the + battery terminal. The cardboard box is insulation to keep that unfused power from causing problems
Second photo shows connection to main relay and power to coil disconnected
Third photo shows washer bottle and HT leads out of the way. All 6 plugs are out too.
Fourth photo tries to show the jumper wire attached to the starter solenoid. When you touch this to the jump lead, the solenoid engages the starter and turns the engine over
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