Diagnostics Equipment Feature
When surging, loss of power, stalling, starting, or even fuel economy symptoms occur the most common component replaced on Common
Rail Diesel (CRD) is the Suction Control Valve (SCV). Most of the time it is not the SCV that is failing. Before reading on please note an important rule: Many people think that removing and replacing a fuel filter is diagnostics, its not. We ask that you first determine where the fault is and once confirmed that it is a related to a fuel system failure, then you can replace the fuel filter. This failure is not at all related to contamination, its confirmed as a manufacturers component failure.
Often mechanics inspect the fuel filter for water. It is known that water is common to cause problems in diesels and that is because unlike a petrolpowered vehicle,, a diesel cannot dissipate the water. Before dismantling a fuel filter, the best way to inspect for water is to use a hand pump and draw fuel through the filter and inspect for contaminates in the container. If the system had water, it would not run well at all. In fact, it most likely will not start, let alone cause an intermittent loss of performance.
In this article I am going to share how we make use of one of extremely popular diagnostic tools to assist in the successful diagnosis of fault codes P0089 fuel pressure low, P2291 Injector Control Pressure (ICP) and P228C. Fuel pressure regulator exceeded performance. This failure is commonly found on the Mazda BT50 and Ford Ranger 2.2 four-cylinder, 3.2 fivecylinder diesel engines. The vehicle has a complaint of poor performance, engine light on yet starts and idles ok. The cause of the fault is the breakage of one one of three plunger springs located with the Siemens/Continental high pressure pump. These springs enable tension to seat the plunger hard against the eccentric cam which rotates as it is driven by the timing chain. This allows a full plunger stroke to take place, thus creating enough rail pressure to maintain stable delivery of pressure to the electronic operating injectors which are injecting fuel at the correct time into each cylinder.
We begin with connecting clear line to a separate fuel supply. This is our popular diagnostic tool The Eliminator. We use a clear fuel line to assist you in seeing if any air bubbles if present. Air within the diesel fuel system is one of its greatest enemies. Many ask me this question- If there was such a leak where air was entering the system, wouldn’t you have an external leak?
Often not. On many occasions when there is a leak present on the lowpressure side (between the high-pressure pump and the fuel tank), the suction of the fuel created from the internal transfer/feed pump of the high pressure CRD pump, does not permit an external leak. Not all common rail pumps have their own in-built suction, also known as transfer pump. We find that 95% of systems can run a separate fuel supply.
Why run the separate fuel supply? Time saved concentrating on one of the two systems can eliminate hours of wasted diagnostics time. Just because this register’s high-pressure fault codes don’t mean it is not a failure of the low-pressure side. Often on this vehicle the scan tool will display P0089, fuel pressure regulator performance outside parameters.
A list of components that have been replaced and still not rectified the fault:
• Complete rail.
• Rail pressure sensor.
• Fuel filter.
• Injectors.
• Suction control valve.
• Electric in tank pump.
The failure is only a spring, but the entire pump must be replaced. First, we must confirm it is a pump and not another component. Once you have connected and test driven the vehicle with an eliminator tank and confirmed this is no air within the fuel system and the vehicle continues to fault, you can now concentrate on the high-pressure side. If the vehicle did run well then you can start tracing back through the low-pressure side to diagnose the fault.
This article we are going to focus on the fault at hand- A high pressure failure. First confirm the rail pressure we are seeing on the scan tool when starting the engine. Ideally a CRD system should reach a minimum of 200 bar pressure when cranking- instantly. Often the fault occurs immediately when the engine is under load whilst driving. In some cases, the code has logged when free revving not moving.
Another confirmation of the failure is read the demand and feedback of the rail pressure on the scan tool. If the demand is relatively higher than that of the feedback, then you are getting closer to determining the fault.
It is quite common and safe practice to remove the entire fuel system and thoroughly clean including the tank. The metal is exceptionally fine and becomes stuck in every part of the system. At any given time, metal may dislodge and flow to another injector causing a failure.
I recommend injectors be replaced at the same time if the pump has a broken spring.
You can determine the spring is broken once you have removed the pump. See the picture below to determine what component you are looking to remove. They’re really simple to dismantle this section of the pump.
There are 3 to remove and don’t worry, the spring is not too high tension so it’s not going to fly out high speed and take your eye out.