It is a relatively common failure that the fuel dispenser does not produce fuel when the oil nozzle is raised. Next, we will solve this problem by analyzing the workflow of the fuel dispenser.
The process of starting the fuel fuel dispenser is as follows：
Raise the nozzle —> the oil nozzle switch is closed —> the main board receives the signal for raising the nozzle —> the main board sends a command to start the motor electric valve —> the motor starts —> the electric valve opens —> Turn on the oil nozzle switch —-> flow meter rotation —-> The oil nozzle starts refueling
Each step in the above process may cause the fuel dispenser to not produce oil after starting,
Therefore, it is necessary to analyze step by step which link went wrong.
1. Check whether the motherboard is working normally
The motherboard is the core of the fuel dispenser, if the motherboard does not work, the fuel dispenser will be paralyzed.
We judge whether the main board of the tanker is working normally, first of all, whether the voltage on the main board is normal,
and secondly, whether the display board keyboard is displayed normally.
The picture below is the bluesky LG series electronic control motherboard. When designing, there are voltage test points on the motherboard, which is convenient for maintenance.
As long as the voltage of the test point indicated on the motherboard is normal, and the display board keyboard display is also normal,
it means that the motherboard is not faulty. The correct voltage in the figure: is VDD=8.2V; VCC=5.0V; the rest can be according to the marked voltage value.
2. Oil gun switch detection
After troubleshooting the main board, judge whether the oil gun switch is working normally. There is an indicator light on the main board of the oil gun switch,
so you can judge the state of the gun switch by observing whether the indicator lights ① and ② in the figure below are on.
3. Determine whether the main board has issued a command to open the motor valve
After the main board receives the signal of raising the gun, it enters the state of starting and refueling. At this time,
the display board will first display all 8, and send a signal to open the electric valve of the motor.
There is a motor electric valve indicator light on the Bluesky LG series electronic control board.
When the light is on, it means that the main board has started the motor electric valve.
At this time, the motor should be in the rotating state and the electric valve is also in the open state.
At this point, there are several situations to judge where the fault point is.
1）The motor turns to normal, the electric valve is also opened,
and the oil does not come out after the oil gun is turned on.
At this time, it is necessary to consider whether the filter screen of the oil pump is blocked.
2）If the motor does not turn, you need to check whether the solid-state relay driving the motor is working properly.
You can first observe the status of the indicator light on the solid-state relay.
The light on indicates that the input signal is normal and then measures the output voltage.
If there is AC220V output, it means that the solid state relay is normal,
and it can be judged that the problem is the motor itself, and the motor needs to be replaced. If the input signal does not output under normal conditions,
it means that the solid-state relay is damaged, and the solid-state relay needs to be replaced.
3）If the motor does not produce oil after troubleshooting, the next step is to check whether the electric valve is working normally.
First, measure whether there is AC220V voltage at the output terminal of the electric valve on the power board.
If there is voltage output and the electric valve does not open, it means that the electric valve itself is faulty,
and the electric valve needs to be replaced. If there is no AC220V voltage output,
it means that there is a problem with the electric valve drive circuit on the power board, and the power board needs to be replaced.
4）There is another phenomenon of the electric valve that needs to be checked carefully,
that is, the output of the power board has AC220V, and the electric valve is not damaged,
but it still cannot be opened. In this case, it is likely that there is gas in the electric valve,
and the gas needs to be discharged. The method is to remove the two spools of the electric valve and reinstall them.
5）If the faults of the motor, electric valve, and oil gun are all eliminated and the oil does not come out,
then it is necessary to consider whether the flow meter is stuck and the flow meter needs to be replaced.
6）Through the above steps, you can basically rule out the failure of the fuel dispenser to start and not produce oil.