High-pressure fuel pump
I have just fitted the fourth high-pressure fuel pump and fuel pressure regulators to my 2005 Vauxhall Zafira.2.2 petrol. At Vauxhall prices, these parts cost £800 and £300 respectively. A while ago, there was a BBC Watchdog report regarding the failure of these pumps. My last one lasted approximately four years, but how long is a fuel pump expected to last? I stripped down the faulty pump and there were three diaphragms, one of which had split. Can these pumps be repaired or spares obtained to repair them yourself? Has anyone else had as much trouble with these pumps as me or am I just very unlucky? GA Moore
The general consensus as to why the high-pressure fuel pump fails is that, due to its position in the engine, it runs in what is effectively a heat trap below the engine cover. This causes it to run at temperatures higher than it was designed for. The rectification of the problem depends on whether you prefer to remove the cover or simply cut away the cover over the area of the pump to allow a greater air flow. I personally favour trimming the cover around the area of the pump – this retains some of the advantages of having the engine cover, without affecting the engine detrimentally.
The other problem is that the vehicle does not have a separately-accessible fuel filter, relying on a microfilter in the fuel tank. This can mean that particles from the original damaged pump could go on to cause more problems if the system is not thoroughly cleaned through.
The earlier Siemens pump has been replaced by a Continental pump, which appears to be less problematic. If the replacement pumps you have fitted are not Continental, I would consider this at the next replacement.
I can find no retailer who is able to supply parts to repair these pumps. There was a seller on ebay who was based in Littlehampton in West Sussex, but they appear to no longer be active.
As you say the tyres are not a particularly low profile, so they won't be contributing excessively to the harsh ride. Changing only the rear springs would unbalance the dynamics of the suspension and could effectively reduce the stability of the vehicle. As the stiffness in the suspension is mainly derived from the springs, replacing the shock absorbers would possibly allow the body to rise and fall more easily, but this alone would not improve the ride quality.