efims wrote:Thanks for giving me something to work on.
I measured Fuel Pump Output voltage vs +12Vdc(ignition) but got about 5-6Vdc(with relay connected). It should be 12V, right?
Instead of giving OVdc to energize the relay, the Fuel Pump relay output gave +6 to 7Vdc, thus the voltage across the relay coil is not sufficient to energize the relay(to power the Fuel Pump).
efims wrote:DMM Positive probe on Igntion 12V+ while Negative probe at Fuel pump output(ie 85 and 86 of relay coil) with relay fitted.
efims wrote:Problem came back...started the car...and after about 30sec, the engine stalled....fuel pump refused to activate.
Measure output and found insufficient 12V(about 4 Vdc only) to activate relay coil.
Could it be the firmware?
Or could it be defective D7(is it true that D7 is to protect flyback for the relay coil)?...could a defective D7 lead to(failing to protect flyback) damage of Q3?
SymTech Laboratories wrote:Keep your negative lead touching ground, then measure everything again using your positive lead.
SymTech Laboratories wrote:You should measure the voltage on both sides of the relay coil with your negative multimeter lead touching ground. Or you can replace D7 and see if that fixes the problem; there aren't many components in this circuit that could fail...
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