Tag: Fuel

Running Repairs – Fuel Pump and Rear Brake Overhaul

While travelling to and taking part in a parade lap at The Silverstone Classic this summer I had a couple of odd incidents.

  • While passing travelling across country, the car cut out and coasted to a stop – restarting after maybe 20 seconds.
  • While on the parade lap at Silverstone the fuel pump (just behind my seat) went crazy – knocking and clattering away.

Knowing that I already had a spare fuel pump ‘in stock’ I decided that would be a good 1st step towards fixing the issue.

The job was a simple one, but included removal and refitting of the drivers seat to gain good access to the retaining bolts.

Before;

After;

Since replacing the pump, the car has had zero problems – and I’m considering it fixed. In fact, the car feels like runs even better, especially at mid-high revs, maybe the old pump had been on its way out for a while.
I also took some time to pay attention to the rear brakes, the handbrake was more-or-less ineffective and, when attempting to bleed the rear brakes at the time of wishbone replacement, I could not undo the bleed nipple.
This turned out pretty time consuming, but easy. I replaced both rear wheel cylinders for the drum brakes and took some care to adjust the (supposedly automatically adjusting) handbrake.
I then re-bled the entire braking system.
The result of this is.
  • The handbrake works without pulling it up to the sky.
  • The car is much more stable under braking.

Upon removal, the old wheel cylinders felt as if notches were worn into the bore, and, my guess is – doing nothing in particular.

Carburettor Rebuild…

So,

I decided that it might improve the WOT(Wide Open Throttle) running by giving the ZX9R B carbs a rebuild.

As a bit of a grounding I watched this fellas videos on  You Tube.

Here’s what I found during the rebuild process.

The inlet manifold take-off pipes for the Megajolt MAP (Manifold Absolute Pressure) sensor were a bit loose – one was off completely – I pushed them all on tightly.

The float heights in the carbs were not even – they should all be 14mm, only 1 was – I reset them by bending the little tags on the float.

I increased the jet size to 1.6mm as per many recommendations. To richen the mid throttle range I raised the needles by adding a washer below each needle stop.

a few little back bits were found knocking about near the jets and needle valves – maybe plastic or hard rubber, i cleared these out.

After a clean up and rebuild – refit – I put them on the car and started it, but fuel came out of every orifice (even the venturi).

Stripping them once more drove me to replace the float needles and seats – reading through some forums I heard that the varnish in worn carbs keeps these things sealing, and that after cleaning this off – if they are worn troubles can arise.

I also replaced the float bowl rubber gaskets to ensure good sealing.

They looked glorious;

2nd Try – the carbs went back in quickly and the car started 1st time, alas though they still leaked fuel – from the overflow pipes – I remedied this by dropping the fuel pressure through the Filter King to around 2psi – at 3 psi the fuel must have been pushing the float valves open.

I found at part to  mid throttle the car is feels like it has more torque and the exhaust note is wetter – this I think is due to raising the needles.

It was still unhappy at WOT though – so maybe going for different main jets once more is the key.

I’m looking forward to balancing them and giving the car a good test in some dry weather to get an opinion.