Can this be done even without the Daewoo Scan-100 tool that no one seems to have anymore? I have the printed factory service manual, and the troubleshooting flowchart for P0300 would have me view the camshaft revolution counter and crankshaft revolution counter to see if the readings increase at the proper rate for the commanded RPMs. There are also cumulative misfire per-cylinder counters that would be really useful if I could access them.
Well, the only fuel injector test I can do is to try another set of injectors. With the Daewoo scan tool, the recommended test procedure would be to install a pressure gauge on the fuel rail Schrader port, with the engine off, command the fuel pump to come on just long enough to pressurize the fuel rail, pulse one injector a few times, and observe the pressure drop. This test is to be repeated with all four injectors, and the pressure drop from pulsing each is to be compared to see if one sprays more or less fuel than the others.
I went to the “you pull it” yard today and got the complete fuel rail with injectors, MAP sensor (factory original, date code 2001), and camshaft position sensor (updated/revised part number, date code 2006). I previously purchased, but have not yet installed the fuel pump (aftermarket brand, date code 2015). The only reason I want to replace the fuel pump is because the gauge will not go above 75-80%, and replacing the instrument cluster (due to a grossly inaccurate speedometer) did not help with the fuel gauge, though it does show the correct speed now.
I assume the first thing I should do is try replacing the fuel pump, which I was planning to do anyways, and install a new fuel filter. If that makes no difference, what would you suggest next? Replace camshaft sensor, or try the replacement fuel rail (with all new O-rings on the injectors of course)?