Fuel Filter

In spite of the owners manual specifying a 5,000 km replacement service interval on the fuel filter, field experience has shown no need for replacing them anywhere near that often and the factory in any case apparently issued a service bulletin revising the service interval to 20,000 kms.  It will depend mainly on the overall cleanliness of the fuel supply - avoid filling your tank right after the fuel tanker has been to replenish your local filling station, for example.

Since my bike was being dismantled for other reasons (such as the seat mounting bracket having broken and the engine upgrade being done), the fuel filter on my bike was replaced slightly earlier than recommended, at 19,000 kms.  If you're doing other work around this area of the bike then it is probably a good idea to take the opportunity to change it early, the part itself is cheap, much less tahn you'd pay someone to fit it.

One local dealer suggested that at the first fuel filter change the standard internal hoses be replaced with stronger/longer ones, so that for subsequent changes the filter can be pulled out by the hoses rather than having to remove the whole fuel tank from the bike.  This may or may not work for you.

Some Moto Guzzi/Ducati models fitted with Weber Marelli EFI ignition use the same fuel filters, and their branded parts are made by Weber.  See the parts equivalence table for details, plus other alternatives.

Filter Replacement Procedure

Strangely, the recommended steps do not appear in the official Laverda service manual, in spite of it being reputed to take over two hours to perform a fuel filter swap.  Here is my take on how to do it.  Note that caution is advised at all stages, as petrol is very volatile.  Don't stop for a smoke anywhere nearby while part way through either!

  1. Ensure that the fuel tank is close to empty, and the motor is cold. 
    • There will always be a small amount of fuel lost from the hoses and injectors as you detach the hoses from the tank.  If there is much over half a tank full of fuel in the tank, the fuel outlets from the tank will spray fuel over the engine as the hoses are removed.  Trust me on this one, it happened to me!
  2. Detach the exhausts from their mounting brackets.
    • either support them in place or remove them from the collector box/x-piece, as their weight will damage things if left unsupported for too long.
  3. Remove the fake fuel tank cover, seat and rear plastic bodywork.
  4. The tank is held in place by two bolts to the rear subframe.  Remove these
  5. Loosen off the two lower subframe fixing bolts, and remove the top two mounting bolts.  Allow the subframe to swing down to give the clearance needed to remove the fuel tank.
  6. Disconnect the two electrical connectors at the top of the tank, for the fuel sensor and the fuel pump. 
  7. The fuel breather tube should be removed. 
    • While you're here, check the tube for kinking, as there is nothing to prevent the tube collapsing.  The tube is thin walled plastic and a kink here could cause the fuel tank to pressurize excessively.   The tank vents through a relief valve, set to open at around 0.4 bar, more pressure than that could cause problems.
  8. Remove the two fuel hoses from the tank.
  9. Swing the tank backwards and pull up and out.
  10. Empty any excess fuel from the tank
    • This will make the next step safer.  Take care here too.  The under seat fuel filler is not designed to aid pouring, and overly hasty work here will spill fuel.  Once again, trust me on this one!
  11. Unbolt the tank flange and replace the filter

Reassembly is the reverse of this procedure.

Some Hints from Phil Stephens

"Some fuel loss on removal of the hoses from the tank to the injectors is almost inevitable as the pressure line will hold pressure for some time. There are two short rubber hoses from the tank to the injection unit, a feed and a return, and if you have a fuel level higher than the return on the front of the tank, fuel will continue to pour out till your loop one of the lines back to link the two tubes. Having learned this, I loosen one of these hoses at the injector end and the other at the tank end so that when the injector unit is lifted off , I can quickly reattach the line still on the tank back to the other stub and seal it off losing only a very small amount of fuel.

"On one of the occasions that I took the race bike's tank out and replaced the filter element, I drilled and tapped the bottom closure plate and screwed in a right angle fitting to allow use of a fuel line drain of the tank. This also serves as the fuel level sight tube with a section of clear pastic tube routed bank to the top tank vent and a T piece there. This gives me a much better idea of fuel load and consumption when racing and an easy drain when necessary.

"When you reinstall the tank top and bottom covers after doing the filter change, take great care to get the sealing ring in correctly. I learned this the hard way when, after installation and complete reassembly of the bike, all seemed well on the initial partial fueling and test run but a major leakage of  fuel on start up at the track with a full fuel load and consequently missed a significant part of the race day."

Fuel System

© Steve Carr, 2001-2007

Site created February, 2000.  Last modified Friday, May 15, 2009

Return to 668 Tech start page

Last updated
30 May 2005