s12 walbro fitting guide

[PukkaSilvia]

On a Modified Silvia turbo to help improve performance and prevent Severe damage from running your engine lean, it maybe time to fit an uprated fuel pump.The 2 most common choices are the bosche unit and the walbro 255. The Walbro is rumoured to be more reliable but i expect they are both good units. The standard s12 pump fuels in the region of 120 litres an hour whereas the walbro for comparison pumps 255 litres.

The General Guide

With the engine running at idle remove the fuse for the fuel pump( second fuse in at the bottom right)After a very short while, the engine should stutter and die. Using the ignition, keep re-starting the engine until it won't fire at all. This should ensure there is a minimum of petrol in the fuel lines and will reduce any back-pressure.

Now firstly for safety disconnect the battery.

Location

The standard s12 fuel pump pump lives inside the petrol tank in a cradle, This can be found under a cover in the boot. Peel back the carpet and you will see it.

Removal

Remove the interior cover(4 SCREWS) to reveal the top of the fuel pump cradle bolted to the fuel tank.

Undo the 2 jubilee clips holding the fuel hoses to the top of the cradle and then use a 8mm socket to undo the 8 bolt fixings that hold the cradle to the tank.


you are now ready to remove the s12 cradle from the fuel tank. It is a tight fit and takes some wiggling and yanking but it does come out.

You will see that the cradle is made up from 2 halfs. you need to remove the lower half of the cradle by undoing 3 10mm bolts and undo the internal pump jubilee clip that connects the cradle lid to the pump.


The bottom half of the cradle will come off easily and the pump will slide out once you have cut the +&- wires to it.

Fitting

Below is a picture of a typical walbro 255 kit with instruction on fitting its pickup filter and connections


You will see that the old pump is larger than the new walbro 255. It also has some rubber spacers on it. i removed the 2 spacers off the old pump and slotted one inside the other and then they fitted perfectly over the new Pump.

Now slot the new pump in the cradle top connecting the old power wires to your new wires supplied in your walbro kit and shrink wrap any join connections that there may depending on the kit. the new inner fuel hose is the same diameter and will slot right over the cradle connection and fasten with a jubilee clip.

Bolt the lower cradle half up with the 3 10mm bolts you undid earlier. The pump should be secure in the cradle as you used the old pump rubber spacer. If there is movement you may want to secure further with zip ties.

Carefully inset the cradle back into the tank making sure the rubber ring gasket that sits between the cradle and tank is still on top of the tank properly.Be careful not to catch the ballcock sender on the tank as you fit the cradle.
Connect the 2 exterier cradle fuel hoses to the top of the cradle.

Testing

Connect your battery and insert the fuel pump hose.

Turn on the ignition and check to hear the pump working and that there are no leaks on the top hoses.

If all is well bolt the cradle in with the 8 8mm bolts you removed earlier and screw down the boot cover.

Smile

Your away to go. Every time you switch on your ignition you can hear that lovely walbro in the boot hummm like it was made in soho and its pure joy