Q. I want to change the fuel filter on my Ducati 998, which sits inside the fuel tank along with the fuel pump, but I've heard that refitting the pump assembly and the attendant rubber seal is a nightmare. Any suggestions?
John Lee, Chesham
A. The pump assembly is held in place with three 6mm shouldered bolts.
To remove it you need three 6mm bolts without shoulders that screw into the threaded holes in the assembly.
As you screw them in, the assembly is extracted from the fuel tank. 998 owner and MCN reader Chris Hall found the bolts from the front mudguard will do the job.
Once the pump assembly has been removed the sealing mechanism – one very large rubber seal – is revealed.
The filter is easy to replace. Incidentally, the rumour that the 998 filter is expensive is not true, it cost about £15.
Also the rumour that the filter for a Vauxhall Vectra 2.0i is the same, also appears to be untrue – all the ones Chris was offered for said car were too long.
But a K-series BMW filter is identical – both are marked "KL145" – and of a similar price.
As you suspect, refitting the pump assembly is where the real problems start. The assembly fits tightly into the 7in diameter hole in the tank, compressing the rubber seal.
Of course every time you attempt to push it home the seal pops out! When you think you have got it in, check inside the tank, it might have popped out inside. Chris spent two hours trying to refit it.
Eventually he found the solution. Grease the seal with Castrol red rubber grease. Rest the assembly in the hole in the tank.
Using three of the front mudguard bolts, pass them through the baseplate holes and screw them into the mounting bolt holes in the tank so the bolts are just bearing down onto the fuel pump base plate. In rotation, screw in each bolt about half a turn at a time.
This drives the assembly into the tank perfectly square ensuring that the rubber seal is compressed evenly and it doesn't pop out.
Once the seal is no longer visible the mudguard bolts can be removed and the actual fuel pump bolts used to drive it fully home and tightened down.
The pump mounting bolts can't be used to start with because they aren't long enough. All-in-all, it’s about 10 minutes work.