Frequently Asked Questions

Got a question about fuel systems? Or want to know what sets KPM Fuel Systems apart from the rest, check out our frequently asked questions below.

If you have a question that isn’t covered, please get in touch with us here.

Why do I need a fuel system upgrade?

Your factory vehicle fuel system is designed to support a certain level of engine power.

The more power your engine can make the more fuel your system needs to be able to deliver.

If you increase your engine power, you may find that your factory fuel system can no longer supply enough fuel for the extra power.

If this is the case, you will need to replace the appropriate fuel system components to be able to correctly support your new engine power levels.

How do I know if I need a fuel system upgrade?

It will be near impossible to know if you require an upgraded fuel system or components, without having the correct test equipment and extensive knowledge.

Every car and setup can be different, we recommend having your tuning specialist advise the correct fuel system upgrades when increasing power.

You can also contact our experts at KPM Fuel Systems should you need further information.

How much fuel does my system need to supply?

You can estimate how much fuel delivery you require as long as you know the following:

  • Your actual or intended engine power
  • Is the engine naturally aspirated or forced induction
  • What fuel/s will you use e.g. petrol, ethanol, methanol etc.

When you can answer all these 3 questions, we can calculate this by the BSFC (Brake Specific Fuel Consumption) to give the estimated amount of fuel supply that your system requires for reliable safe performance.

You or your tuning specialist can contact KPM Fuel Systems and one of our experts will be happy to calculate this for you.

What upgraded fuel system components do I need?

Every vehicle and project can require differing components to ensure perfect fuel delivery for your power level and application. Some of the most common components that you may require are:

  • Fuel Injectors
  • Fuel Pumps / or modules
  • Fuel Pressure regulators
  • ECU retuning / calibration

It is important to have a full understanding of your individual vehicles fuel system and engine power requirements before selecting required components. This will ensure that you only invest in a properly engineered fuel system and money is not wasted on unnecessary, incorrect or ineffective parts.

What are the different fuel injectors available?

Fuel Injectors come in all different sizes, fitment shapes and internal differences.

The main objective is to find a quality injector brand that complies with your vehicle computer, flows the correct amount of fuel, fits your engine, injector rail and wiring perfectly.

All injectors are rated to how much fuel they can flow and how they flow it.

This is called the ‘character’ data of an injector. It is extremely important that when you purchase an injector, it is supplied with its own specific ‘character’ data.

Is it really necessary to have injector data?

Yes. Without exact injector ‘character’ data, your engine can not be tuned to its optimum performance, reliability and even fuel economy.

All injectors have character data, including your standard factory injector. Your engine computer will recognise this injector because its data has been programmed to it from factory.

When replacing the standard injector with a new upgraded injector, the engine computer will require the new injector ‘character’ data to be uploaded to run the engine correctly.

Your tuning specialist will require this data to input into the engines tuning software so that your engine management system will deliver correct and exact fuelling under all conditions.

Not having the data will require your tuner to ‘guess’ and input inaccurate settings that will be ‘close enough’ however never allowing for a precise tune.

Is it really necessary to have a matched set of injectors?

Yes, especially for high flowing injectors.

All fuel injectors that are manufactured by major injector companies (e.g. Bosch, Siemens) have a level of flow tolerance allowed between each injector.  Bosch has a +2/-3 % variance on many of their injectors.

This is fine on injectors that flow smaller amounts of fuel for most standard power level applications. However as engine power demand increases, the injector sizing increases and the variance becomes exaggerated.

For example:

  • Standard injector flow 300 cc with +2/-3 % variance = +6cc / -9cc variance
  • High injector flow 1000cc with +2/-3 % variance = +20cc / -30cc variance

To ensure that we have as little variance between injectors as possible all KPM injectors are match set to ±1% variance

You can now see the variance for a 1000cc injector has dropped to ±10cc.

This becomes extremely important when you are fine tuning a high powered engine and demand a perfect balance of fuel being delivered to each cylinder.

Do bigger fuel injectors make more power?

No, just by fitting bigger injectors does not make power.

Fuel injectors support power, not make power.

You will only need larger injectors when the power level of your engine increases to a level that demands more fuel.

What are surge tank fuel systems?

A surge tank fuel system is generally a small supplementary external fuel canister separate from the vehicles main fuel tank. They can be anything from 2 litres to 5 litres in capacity.

Its purpose is to house an extra fuel pump/s to support the standard fuel pump in supplying extra fuel to the engine.

The surge tank is mounted in an external position under or in the vehicle and is connected to the main fuel tank by fuel lines. Fuel is delivered to the surge tank by the standard in-tank fuel pump.

The large capacity fuel pump/s in the surge tank then delivers fuel to the engine at a higher volume than would be otherwise possible with the standard in-tank pump alone.

What are in-tank module fuel systems?

In-tank fuel modules are canisters housed internally in your vehicles fuel tank. The fuel module canister houses the fuel pump, fuel pick up and fuel pick up strainer.

The fuel module is mounted internally at the bottom of your fuel tank and surrounded by fuel.

The fuel module delivers fuel directly to your engine.

Almost every vehicle worldwide is manufactured with an in-tank module fuel system.

If you require more fuel delivery due to increased engine power, your fuel module can simply be replaced with a higher volume unit.

What is the benefit of an in-tank module versus a surge tank system?

A correctly engineered and designed in-tank fuel module system far outweighs any reason to utilise surge tank fuel systems.

The main reason for this is the positioning of the in-tank module, in the main fuel tank.

The main advantage of being housed in the fuel tank is that the fuel pumps are surrounded by a large mass of cool dense fuel. Generally, even on a near empty tank, most vehicles still have a good 8-12 litres surrounding the pumps and on a full tank, 60 litres plus. This compares to a maximum of only 5 litres and down to as little as 2 litres on surge tank systems.

The greater mass of fuel you have surrounding the fuel pumps the cooler it keeps the pump/s and fuel.

Cool dense fuel is vital for maximum engine performance, pump performance, power, and best economy.

The larger the pumps, or the more pumps you upgrade to, the more heat will be dissipated into the fuel surrounding them. Therefore being housed in the main tank is the perfect location.

An in-tank module being housed and sealed in the main tank also is silent, does not emit fuel smell, is safe and is also legal.

The only possible reason to consider an external surge tank fuel system is that there may not be an off the counter in-tank module system available for your particular vehicle model.

What fuel system is standard in my car?

As far as we know, all vehicles worldwide are manufactured with an in-tank fuel module system.

All Australian delivered vehicles definitely are.

Can I use ethanol fuels in my current fuel system?

If your vehicle was built from manufacturer to support petrol and ethanol, yes you can.

If your vehicle was built from manufacture for petrol only, no you cannot.

Ethanol is a very abrasive fuel and if your vehicle fuel system was not designed for it, you will definitely have failures.

You can however, retrofit most fuel systems to run ethanol.

What fuels can I use with KPM Fuel system components?

KPM Fuel System components are all designed to be used with all fuels including ethanol variants.

You may still need to consider other components if upgrading your fuel system including fuel lines, fittings canisters and engine computer re-calibration to suit.

KPM Fuel System experts can best advise you on your individual need.

What is a Fuel pressure regulator?

A fuel pressure regulator is a device that is connected to your fuel system to control the amount of fuel pressure in the fuel lines and fuel rails.

This allows your fuel system to run at a pre-regulated fuel pressure, thus the name Fuel Pressure Regulator.

Do I need an upgraded fuel pressure regulator?

If you are upgrading your fuel pumps or supply, you will find that you generally will require an upgraded fuel pressure regulator.

An upgraded fuel pressure regulator needs to be matched to the extra fuel supply and be able to regulate fuel pressure accordingly.

What fuel pressure should I have?

There are many fuel system designs that run widely varying fuel pressures.

The majority of fuel systems upgraded by enthusiasts are called Manifold or Port Fuel injected systems.

Vehicles with Manifold or Port Fuel injected systems run approximately 400 kPa pressure depending on vehicle model.

To achieve the best performance from your fuel system, it is wise to design your fuel system to run at 350-450 kPa.

Why do I need a wiring kit for KPM Fuel Systems?

Your vehicle electrical system is designed and rated to the electrical current needed to supply the standard fuel pumps.

When upgrading to larger fuel pumps/module, the larger pumps may draw more electrical current than the standard pumps.

If the correct electrical/wiring components are not replaced to suit, you may find that your new larger pump will not be able to flow to its full potential.

Even worse you may overheat the standard electrical system and wiring and create complete electrical failures.

Do I need a fuel filter?


When upgrading your fuel system, take into consideration the filtering process.

Always replace your fuel filter with at least a 10-20 micron high flow quality filter.

If you are using Ethanol fuels, you must use a specifically designed ethanol fuel filter.

The fuel filters are one of the least expensive fuel system components that can easily be overlooked and that can cause the most problems.

Is there anything else I need, or any other advice?

The main consideration is good reliable advice.

Your fuel system must be engineered to operate correctly and reliably for your intended application.

This knowledge can only come from professionals that have been trained and have a full working understanding of modern Electronic Fuel Injected vehicle fuel systems.

Sound advice from a fuel system specialist will ensure that you plan and purchase all the correct components without wasting money on un-needed or substandard components.

Time after time we see customer’s vehicles that have been modified with either part fuel systems, incorrect or unneeded components that are both a waste of money or even worse, detrimental to engine reliability.

As with anything, good advice will ensure that you end up with a correctly engineered fuel system without wasting time or money.

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