Verification process starts from external inspection. Apart from obvious and noticeable mechanical damage, such as broken return spring or piston, the following defects may be detected by this method:
– worn external seal and damage to housing around their settlement,
– considerably contaminated sprayer nozzle,
– damaged element fastening the return spring,
– damaged upper element of piston (plate),
– worn surface of ball tang.
Another step is electrical measurement of coil in order to assess its initial efficiency. If, after these procedures, the fuel injection unit is qualified for repair, cleaning starts. After removing loose impurities, sprayer nozzle is cleaned carefully in ultrasound washer.
Fuel injection unit prepared in such a way is located in a special attachment, mounted on Bosch testing table. The final stage is a selection of programme, which chosen for each fuel injection unit performs its test automatically. It consists of several stages, during which injection dose is measured with given rotations of drive shaft and properly selected length of an electric impulse. The values measured are displayed on the computer screen, which automatically evaluates their efficiency.
When fuel injection unit test provides incorrect results, its repair may be performed. The process begins with disassembly of components and their condition control. After removing the spring, external surface of piston is inspected carefully. It may not have any wear and tear signs such as scratches, corrosion centres or material loss. During repair, new original nozzle of the sprayer is used. After replacement of damaged elements, the fuel injection unit is re-tested at the testing station. If all measurement values do not exceed the required range, the Client receives the repaired fuel injection unit along with appropriate report, confirming professional performance of repair.