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Home » Workshop » Auto Electrics » Electric Fuel Pump

Why upgrade to an electronic fuel pump?

Electric fuel pumps are standard fitment on all fuel injected cars which need plenty of pressure to work correctly. However there are many advantages to adding the correct electric fuel pump to a car running carburettors.

Mechanical fuel pumps run at very low pressures and back in the day when we had good old 4 star and the cars were being used regularly they did a passable job. However fuel and our usage of classic cars are quite different to those golden years.

On leaded fuels, mechanical pumps were adequate to give the carb enough fuel in its float chamber. Yet with the heat from the engine, and the volatility of unleaded, you can often find that the petrol is evaporating before it has reached the engine. Mechanical pumps simply cannot ‘keep up’ with demand and the engine will either fluff or cut out.

Instant fuel pressure

Classic cars also goes long periods of time between use. Fuel flows back towards the tank and the engine has to churn over for a while before enough fuel is drawn up to start the engine. This puts unnecessary pressure on both the starter motor and battery.

There are many modern fuel pumps that are designed to run at between 1 and 1.2 Bar, about 0.4 higher than an average mechanical pump. When coupled with a regulator they provide constant fuel pressure from start right the way through to the top of the rev range. It is easy to see how this adds to the cars reliability performance and ease of starting.

How are they fitted?

Generally a fuel pump is fitted on the underside of the car, between the fuel tank and the chassis. It is given a ‘live feed’ from the fuse box and is switched on the ignition. When the ignition is rotated through its 2nd position, the fuel pump primes and the system is pressurised. Within a few seconds the engine is ready to start. We often fit a regulator in the engine bay. This controls the pressure and hold a small reservoir of fuel close to the carbs helping smooth out sudden demands when the throttle is held wide open.

Are they noisy?

Most of us would have heard the distinctive tap, tap, tap of an SU Pump commonly fitted to British sports cars such as a Jaguar E-Type. The pump is triggered by a set of points, much like a distributor. The modern pumps we use are almost silent. They are also mounted on rubber blocks don’t transmit the noise into the passenger compartment.

If you love the original look, we can also upgrade the older style of SU electric pump to an electronic variety. These look identical, you’ll never hear it and you won’t have to give it a tap to help it push the petrol through the lines when it is getting old and tired.

Home » Workshop » Auto Electrics » Electric Fuel Pump
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