• The specifications of a diesel injection pump will determine the pressure and speed at which fuel travels to a cylinder.Vintage Car Engine image by itsallgood from Fotolia.com
  
  Diesel engines require a precisely metered amount of fuel, under high pressure and at the right time, delivered to the injector. Unlike their gasoline-powered counterparts, diesel engines require fuel injected indirectly into the cylinder---the job of a diesel injection pump. Diesel injection pumps are not serviceable except by a few diesel experts. Mechanical diesel injection pumps have begun to give way to alternative injection systems, such as common rail diesel systems and electronic unit direct injection systems, which comply with international emissions standards.
  
  

VE Type Injection Pump

• VE stands for "Verteiler," German for "distributor" or "divider." The Verteiler injection pump, used in Volkswagen diesels and other small diesel engines, has one fuel metering plunger connected to a distributor that delivers the metered fuel to the correct cylinder.
  
  

Inline Injection Pumps

• Inline diesel injection pumps do without the distributor by having one fuel metering plunger for each cylinder. The advantage of the VE pump lies in the fact that it has fewer moving parts, but the moving parts of inline injection pumps are less complex and less expensive to repair.
  
  

Common Rail Direct Fuel Injection

• Low-pressure fuel pumps have given way to high-pressure alternatives, such as common rail direct fuel injection systems, which can deliver pressures of up to 26,000 lbs. per square inch. Both diesel and gasoline engines make use of common rail technology. Most manufacturers under their own brand of this technology; for instance Fiat has the JTD, GM the CDTi, Honda the i-CTDi and Ford the TDCi, to mention a few.