Diesel Engine Fuel System Specification Example for City Buses: Sealed Unit
Diesel Engine Fuel System Specification Example for City Buses: Sealed Unit
This is a worked specification for diesel engine fuel system in a sealed unit programme. It is the document we would send a buyer who asks what exactly they are getting: the material, the dimensions that are actually controlled, the finish, and the checks that happen before anything is packed.
The sealed unit version exists because the duty cycle on city buses is not the same as on a showroom vehicle. Where the two are specified identically, something fails later — usually warranty claims traced back to a single lot.
Example specification
| Item | Diesel Engine Fuel System |
|---|---|
| Application | City Buses |
| Version | Sealed Unit |
| Base material | Silicone |
| Controlled dimensions | 6 key dimensions, recorded per lot |
| Tolerance band | ±0.5 mm |
| Finish | painted |
| MOQ | 200 pieces per specification |
| Sampling | 14 working days, 3 days per revision |
| Compliance | IATF 16949 |
How the example is built up
- Start from the duty cycle, not from the catalogue photograph.
- Fix the base material in writing — Silicone, in this example.
- List the dimensions that are actually controlled and the tolerance on each.
- Name the finish and what it has to survive.
- State the inspection level and who pays when a lot fails.
Processes involved
- shot blasting
- assembly line testing
- gravity casting
- anodising
- powder coating
- electroplating
Where this example applies
Programmes that run sealed unit most often specify this build for city buses. Related applications include aftermarket retail, passenger cars, workshop replacements, agricultural trailers, boat trailers.
Checks before packing
- Dimensional report against the approved drawing.
- AQL 1.5 sampling on the finished lot.
- Finish inspection under agreed lighting.
- Carton drop test on the first lot of a new packing specification.
Questions buyers ask
Can the specification be held on file?
Yes. Once approved, the specification is recorded against your part number so a reorder reproduces the IATF 16949-compliant build instead of a fresh interpretation.
How long does sampling take?
Samples leave the factory in 14 working days, and each revision round adds about 3 days once you have seen the first piece.
What testing is included?
Standard lots ship with dimensional and hardness reports. IATF 16949 documentation is issued with the shipment when your market requires it.
What happens if a lot fails inspection?
The lot is re-inspected against the golden sample, and replacement pieces ship on the next available booking at our cost.
Share a sample or a drawing and we will quote against a written specification, not against a photograph.
