FAQ for Fuel Pressure & Flow Test Equipment and Fuel Pumps

 

1) Why do we need to test the fuel flow? What can the pressure and flow equipment do for us?

2) What kind of fuel can be tested by this equipment?

3) What's differences between return-type and returnless fuel injection system? Can this tester work for both system?

4) What's the difference between OEM replacement pumps and high flow pumps? Can your Tester test both types of fuel pumps?

5) How is fuel pressure regulated in fuel injection system?

6) Why are safety issues so important while doing fuel system maintenance or modification?

 

 

1.  Why do we need to test the fuel flow? What can the pressure and flow equipment do for us?

The fuel system pressure is one of the first fundamental checks of a fuel-injected engine. However, fuel pressure or maintaining the pressure in the fuel system results from a fuel volume or “flow” within the fuel system. Your vehicle might have a correct fuel pressure at an idle speed, but that doesn’t mean the pressure in your vehicle’s fuel system will be right at other speeds. Also having a correct pressure in the garage doesn’t necessarily mean that the fuel pressure is right on when the vehicle is moving.  Basically,  a fuel volume at a certain pressure is the key to maintaining system pressure at any situation. Therefore, modern electronic fuel injection systems need a proper volume of fuel as well as proper pressure for good performance.

The following chart shows you a proper volume of fuel needed to maintain the proper pressure for a specific Horse Power.

Brake Horse Power	Fuel Requirements   ( naturally-aspired )	Fuel Requirements   ( Turbo/Super Charged)
200 HP	63 LPH  or  17 GPH	76 LPH  or  20 GPH
250 HP	79 LPH  or  21 GPH	95 LPH  or  25 GPH
300 HP	95 LPH  or  25 GPH	114 LPH or 30 GPH
350 HP	111 LPH or  29 GPH	133 LPH or 35 GPH
400 HP	127 LPH or  33 GPH	152 LPH or 40 GPH
500 HP	158 LPH or  42 GPH	190 LPH or 50 GPH
550 HP	174 LPH or  46 GPH	209 LPH or 55 GPH
600 HP	190 LPH or  50 GPH	228 LPH or 60 GPH
650 HP	206 LPH or  54 GPH	247 LPH or 65 GPH
700 HP	222 LPH or  59 GPH	266 LPH or 70 GPH
750 HP	237 LPH or  63 GPH	285 LPH or 75 GPH
800 HP	253 LPH or  67 GPH	304 LPH or 80 GPH
850 HP	269 LPH or  71 GPH	323 LPH or 85 GPH
900 HP	285 LPH or  75 GPH	342 LPH or 90 GPH

 

The fuel system is a mystery to most technicians. With this equipment, technicians will have the tools in their hands to easily understand all the different phenomenon of fuel systems. This equipment will make their jobs much easier when it comes to working with fuel systems. It will allow for the diagnosis of whether your vehicle still has adequate fuel after heavy modifications. Though there are countless other unlisted used for this equipment; the details the equipment can provide for you regarding your fuel system to this date are as follows:

i) Testing fuel system pressure and flow simultaneously in a return system;

ii) Testing fuel system pressure and flow simultaneously in a return less system;

iii)  Troubleshooting fuel system and its components (fuel pumps, pressure regulator etc.);

iv)   Finding fuel requirements for a modified vehicle;

v)    Testing fuel injectors on vehicle;

vi)   Testing fuel pumps and other fuel components off vehicle.

 

2.  What kind of fuel can be tested by this equipment?

The flow marks shown on the equipment were designed for gasoline. Because the density of gasoline varies from 0.66-0.75 (g/cm), the number you read from your flow meter has ±3.6% errors, meaning if your flow meter displays 150 LPH, the real number should be within 150±3.6%X150 and range from 144.6 to 155.4 LPH.  

You can also test combinations of fuels such as gasoline & alcohol as long as you are multiplying a correction number to the testing results. Please contact us to find a correction number for a specific combination of fuels.

 

3.   What's differences between return-type and returnless fuel injection system? Can this Tester work for both system?

Return-type fuel injection systems have been around for years. As the name implies, return-type systems circulate fuel in a loop. Beginning inside the fuel tank, an intake filter or screen is usually mounted on an electric pump. Fuel is pumped through supply lines and an in-line filter to the fuel injector rail. Proper fuel pressure is commonly maintained in the injector fuel rail by means of a vacuum modified pressure regulator. Since most fuel pumps are capable of pumping more volume than needed by the injectors, extra fuel is bypassed through the pressure regulator and return lines back to the tank.

Returnless fuel injection system is notably different from return-type, generally resulting in greatly reduced fuel flow through the system. Since there is no return line, all fuel flow is directed toward the fuel rail and must leave through the injectors.

Yes. This tester is able to work on both return-type and returnless fuel injection system. Please check our user's manual for the detailed instructions.

 

4.  What's the difference between OEM replacement pumps and high flow pumps? Can your tester test both types of fuel pumps?

The OEM replacement pump are capable of providing enough fuel for only the capabilities of the engine as designed and installed by the manufacturer. Users who seek higher horsepower output from their vehicles have higher fuel requirements. The OEM pump often becomes dangerously inadequate when providing fuel to a heavily modified engine. High flow pump are capable of providing enough fuel for your modified engine. Since additional flow above engine requirements will simply be returned to the fuel tank, too much flow is far better than too little.

Yes. This tester can test the flow volume up to 400 LPH, which can support 1260 HP with a naturally-aspired system.

 

5.  How is fuel pressure regulated in fuel injection system?

There are two types of fuel pressure regulated system in current fuel injection vehicles: 1) Return-type system which has pressure regulator after injectors; 2) Returnless system which has pressure regulator before injectors.

Both of regulators have same principles: when system pressure reaches a certain value, the regulators are just like relief valves to allow extra fuel to leave the system.

The fuel injection pressure systems therefore require that the fuel pump is able to provide more pressure and flow than is actually needed by the fuel injectors so that effective regulation can be enabled. When the vehicle is making little horsepower (such as when it is idle) the fuel pressure regulator is returning large quantities of fuel back to the fuel tank to keep the fuel pressure from spiking about what is required. When at maximum horsepower output, a smaller amount of fuel is being returned since more is being used by the engine to make power.

 

6.  Why are safety issues so important while doing fuel system maintenance or modification?

Only certified and licensed automotive technicians should do fuel system maintenance or modification. This is especially true of fuel injected fuel delivery systems, because the high pressure in these lines can be maintained for hours or even days. Gasoline vapors are highly explosive. They can be easily ignited by many different heat sources (including static electricity) and can travel unseen for long distances to be ignited, only to return in the form of flames to the fuel source. Dynapex Performance and its partners and parent corporation make no express or implied approval of any of its products for any application. The buyer holds the sole responsibility for the selection, purchase, safe installation, and safe use of any of the products on this website.