Injector cleaning
Q I have an Astra 1.9 CDTI 150 with the Z19DTH engine. The car was spluttering when revved from cold to 3000rpm, so I took out the injectors and cleaned the tips with carb cleaner. When I put everything back together, I recut the injector seats and used new copper washers, but now it won’t start. I plugged in Opcom, which said ‘low fuel pressure’, and when I loosened the fuel line while cranking, the fuel was coming out very slowly. Isn’t it supposed to come out of the metal fuel lines under pressure when cranking? Wayne Erwin
A The Z19DTH engine is a common-rail unit, so the injector pipes must never be slackened off when the engine is cranked. The reason for this is that the injection pressure is extremely high and the pressure at which the diesel exits is capable of causing severe injury.
My second comment is that spraying the injector tips with carb cleaner would have very little effect as they are very complex. The injectors are coded to the ECU and if they weren't replaced in the same order as they were removed in the same cylinder, the ECU would need to be programmed with the injector codes.
The fact that you have no fuel pressure at the injectors may be due to the diesel running back down while the pipes were disconnected. If the low-pressure pump in the tank is failing, it may not be feeding the high-pressure pump, which could have run dry. The high-pressure pump will not be able to get sufficient fuel to begin pumping. Running this pump dry can cause wear very quickly and result in further problems.
I would first check that the lowpressure pump in the tank runs for a few seconds when the ignition is first turned on. If it does, check the fuel filter and ensure it is clean and full of fuel. Then move onto the feed to the highpressure pump and ensure this is being fed. If the high-pressure fuel pump is being fed, the problem may be that this pump has failed. One of the tell-tale signs of this is small metal fragments which travel round the system and get trapped in the fuel filter. This is the worst case scenario and hopefully not applicable to your Astra.