When it is found that the diesel engine is difficult to start, the power is reduced, and the fuel consumption is increased, the fuel injection pump plunger and the oil discharge valve coupler should be dismantled when the fuel injection pump and the fuel injector are still not improved. For example, the plunger and the oil discharge valve are worn to a certain extent. The degree should be replaced in time, do not insist on reuse. The loss of the diesel engine caused by the wear of the even parts, the loss of fuel consumption, the lack of power and so on far exceed the cost of replacing the replacement parts. The power and economy of the diesel engine will be significantly improved after replacement, so it is necessary to timely wear and tear. Replace the parts.