Diesel Engine Fuel and Injector Problems

Mangement of Injector/Fuel starvation issues - bio-diesel

Background

The use of biodiesel and diesel/biodiesel blends can introduce issues associated with injector malfunction as result of either contamination or degradation of the fuels (biodiesel part of product)

Biodiesel essentially are derivatives of vegetable oils which under certain circumstances either due to contamination or biodegradation can break down into organic acids which can form wax like deposits and corrosive products that can either block in-line fuel filters or become deposited at restricted flow points (injector tips). A combination of heat/breakdown can subsequently result in corrosion.

Other traditional issues associated with the use of diesel must also be taken into account –such as particulates, water, bacteriological and carbon formation. All of which can lead to restricted flow/filter issues leading to fuel starvation resulting in poor engine performance.

Critical Criteria to monitor

The quality of the actual biodiesel used –both as neat or in a formulation (eg 5%) is critical. Testing of biodiesel is complex –especially in a blend. Contamination with water, residual organic acids and esterification base metals can result in slow breakdown, especially in storage, of the biodiesel into the organic acids associated with the issues described above. Storage issues normally associated with diesel are likely to result in a faster breakdown of the biodiesel resulting in long term stability issues of biodiesel as compared with traditional diesel.

Rapid cost effective assessment of diesel/biodiesel quality is required. The testing should be directed towards both fuel delivery/storage tanks and on board vehicle tanks.

Water, acidity, particulates and bacteriological content are easily monitored. Limits of some of these materials are available in the appropriate standards where as others are only as guidelines where testing can demonstrate change from fuel delivery quality which may influence the resulting performance of the fuel. Actual biodiesel content of the fuel may also be important and easily determined using Infrared Spectroscopy which at the same time can indicate the presence of organic acids which are of concern

Other more involved testing is available such as fuel oxidation stability, cold filter plugging point or even full specification testing (EN14214; EN590) Such analysis is complex, time consuming and more importantly costly.

Deposit/filter examination can also be provided which could quickly identify the source/type of issue resulting in effective actions.