The concrete gasoline grinder changed the spark plug, and the oil generator still won't fire because the ignition coil is broken, and the crankshaft position sensor is broken, and third, the wiring problem. You can use the car special multimeter, measure the ignition coil plug, see if the computer signal is coming, if there is a signal is the ignition coil is broken. At the same time, you can check whether the gap of the spark plug just replaced is too large, too small or leakage, which can cause no fire. For reference.

I'm talking about a diesel polisher, and I changed the oil, but it won't start!
This situation may be the oil line into the air so can not start, the air can be clean, there is the engine sticking cylinder, need to repair the engine, it is recommended to ask a professional overhaul.

How to exhaust the air
1) Conventional method: unscrew any one of the exhaust bolts at the upper end of both sides of the fuel injection pump for several turns, and squeeze the hand oil pump until the discharged diesel is continuous, smooth, and no bubbles, issuing a "crunch, crunch" sound. Then tighten the bleed bolt and press the oil pump back to its original position. If you do not have the right tool at hand to open the bleed bolt on the fuel injection pump while on the road, loosen any of the fittings from the diesel filter to the fuel injection pump, pump oil with a hand pump until the fittings remove a clear, bubble-free oil flow, then continue pumping oil with a hand pump and tighten the fittings while pumping oil. If there is no wrench to loosen the joint in the pipeline, you can squeeze the hand oil pump repeatedly until the low pressure oil line pressure in the oil delivery pump to the injection pump section is high enough, the fuel from the relief valve into the fuel return oil line, and the gas in the oil line will be discharged from the relief valve. 2) Fuel injection pump high-pressure oil pipe exhaust: if the diesel engine is not running very stable, and there is still air in the oil system is suspected, the following methods can be further checked and excluded. Start the diesel engine to run at a low speed, and then use a wrench to loosen the high-pressure tubing joint on the injector in turn, if there is no air in the fuel, there will be no bubbles.