Fuel Pump Controller - madhu.com (2022)

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Fuel injection systems run at a fairly high pressure, typically 43.5 PSI. It's about the same pressure as common household water supply. Generating this pressure requires a fuel pump and pressure regulator. Most EFI systems use a return type system in which a mechanical regulator limits fuel pressure and routes excess fuel back to the fuel tank. Typical automotive pumps require as much as 10 Amps average current to operate. Motorcycle pumps require about half as much current. EFI fuel pumps are quite inefficient, very little of the electrical power is used to push fuel. Most of the power is lost in heat.

To reduce power demand and the need for a fuel return line, I decided to design my own electronic fuel pressure regulator. Here's a high level block diagram:

Fuel Pump Controller - madhu.com (2)
Fuel Rail Pressure Controller

The electronic fuel pump controller operates as a digital control system. Pump pressure is measured by a fuel pressure sensor. A microcontroller monitors this pressure and modulates pump voltage to maintain a constant pressure. A high power MOSFET capable of 35 Amps maximum drain current drives the pump motor. The MOSFET is capable of driving motorcycle or automotive pumps.

The fuel pump controller has gained a fair amount of interest by DIY fuel injection enthusiasts. If you are interested using the controller with your car or motorcycle, an order form is below.

The kit requires basic soldering of through hole parts and connecting wires. Surface mount parts are pre-soldered and programmed on the board, so no special surface mount soldering skills are necessary. Details on the assembly instructions and connections are described below. For more information, send email to madhu@madhu.com

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Shipping within the continental US is free.

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For other locations, visit USPS and select Small Flat Rate Box to determine shipping costs.

A fuel pressure sensor is not included, see below for suitable sensors.

Details

It turns out that many cars use electronic Fuel Rail Pressure (FRP) sensors to control fuel system pressure.

There are several advantages to this system:

  • It's returnless
  • It requires less power (about 2.5 Amps max)
  • A standard motorcycle petcock/inline filter can be used
  • Fuel pressure is adjustable

Bosch makes FRP sensors that are used in many Ford cars and trucks. You can find them on eBay or at a junkyard. It appears to have a transfer function that is identical to Freescale five bar pressure sensors. I don't think this is a coincidence.

Here's a picture of the FRP sensor mounted on the bike and the control circuit:

Fuel Pump Controller - madhu.com (3) Fuel Pump Controller - madhu.com (4)

The AVR microcontroller adjusts pump motor speed using a digital proportional-integral (PI) control algorithm. Viscous damping due to fuel flow restrictions obviate the need for a derivative term. The AVR samples system pressure at approximately 8kHz and adjusts pump voltage using pulse width modulation. It maintains constant pressure with only a few percent ripple. It's actually more accurate than a mechanical regulator under certain conditions. Given that injector flow rate is proportional to the square root of pressure, the flow rate does not vary much, if at all.

The pump itself was removed from a 2006 Suzuki GSX-R600 in-tank pump assembly. It's a Mitsubishi UC-T30 that requires roughly 4 amps at 12 Volts. This pump is widely used on motorcycle and some smaller cars. Here's a picture of the original pump mounted on the bike:

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Fuel Pump

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One of the ports on the end cap is the low pressure supply from the fuel tank through a standard on-off petcock. The other port is a breather line to vent any trapped air within the end cap.

In practice, the pump controller works quite well. There were two issues with this solution. On hot days (above 90 F), the pump proper can get fairly warm after about 10 mins. This primarily occurs at idle or low RPM when insufficient fuel is flowing through the pump to cool it off. EFI fuel pumps tend to be very inefficient as only a very small fraction of the power they require is used to push fuel. The pump itself can take plenty of heat, it's the gas that can't. Above 120 F, gas near the surface of the pump inlet can boil, which causes the pump to cavitate and lose pressure. The other issue is that pumps usually have a pressure relief valve that can leak slightly, maybe a drip once in a while. While the average pressure is constant, occasional pressure spike can cause the relief valve to drip.

A better solution is to immerse the entire pump in a small tank, that's how most pumps are designed to operate. This way, the pump has sufficient cooling and any drips from the relief valve are contained. I used an aluminum tube 2" in diameter and about 7" long. This works really well.

Bosch 4-pin FRP sensors

Bosch 4-pin FRP sensors are used on some later Ford cars, the 2006 Ford Focus for example.

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Several Ford part numbers exist:

  • 3F2E-9G756-AD
  • 3F2Z-9G756-AC
  • 5C3Z-9G756-AA

Ford part 3F2E-9G756-AD has been tested and known to work. The others appear to be identical, but have not been tested. These sensor often appear on eBay with the description INJECTOR PRESSURE SENSOR. They are usually available for low cost.

I have read that this connector will fit the sensors above: Ford P/N 3U2Z-14S411-UC

  • Bosch 4-pin FRP sensor
  • Pin connections are 1234 left to right looking at sensor pins, fuel port down
    • 1 - fuel pressure signal
    • 2 - +5v
    • 3 - fuel temperature signal
    • 4 - ground
  • Estimated pressure
    • 0.50 volts – 0 PSI
    • 1.2 volts – 10 PSI
    • 1.65 volts – 20 PSI
    • 2.2 volts – 30 PSI
    • 2.75 volts – 40 PSI
    • 2.89 volts - 43.5 PSI
    • 3.45 volts – 50 PSI
    • 3.9 volts – 60 PSI
    • 4.6 volts – 70 PSI

Ford 3-pin sensors

Earlier Ford cars (2000 Ford Contour, Mercury Mystique, Cougar etc.) use 3-pin FRP sensors. These are functionally similar to the 4-pin Bosch sensors, but do not produce a temperature signal. These are typical part numbers that are known to work:

  • F8CF-9F972-FF
  • 9E26C-84FWC
  • 9D29b-830K9

These sensor often appear on eBay with the description Sensor - Fuel Injector Pressure. They are usually available for low cost.

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These are the pin connections:

Ford Sensor PinDescription
1+5 Volts
2Ground
3Pressure output

AEM Sensor

The regulator circuit is known to work with AEM sensor part number 30-2131-100. It has a 1/8" NPT male thread:

Fuel Pump Controller - madhu.com (7)

Alternate sensors

This sensor found on eBay seems to work also. It's nearly identical to AEM sensors at a lower price.

Fuel Pump Controller - madhu.com (8)

Pumps

In general, most 12 Volt pumps that requires less than 10 Amps maximum tend to work well. I have been told that Walbro GSL series Gerotor pumps are not well suited to PWM controllers like this one. This is because PWM pulses will cause the gears to hammer, fatiguing them. Turbine pumps seems to work well, as long as they are always gravity fed because they don't self prime.

The controller has been tested with Mitsubishi pump model # UC-T30 and pumps from Suzuki LT-R450. The UC-T30 is used in Suzuki GSX-R600 in-tank pumps, as well as other vehicles. For very low power installations, the LT-R450 is a good choice. It requires under 2 Amps max. Even less current will be required when used with the pump controller based on fuel demand. Pumps from the Honda Rincon has also been suggested as another low power alternative.

Also note that in-tank pumps usually have a built-in pressure relief valve that tends to leak a small amount of fuel, so it's best to immerse them in a tank or build a small housing that is full of fuel. This also helps with cooling because these pumps are not efficient and can overheat easily.

Kit Assembly Instructions

Download assembly instructions in PDF format.

Pump controller wiring

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There are two sets of wires. The larger, 20 AWG wires connect to +12 Volt power and the motor. The colored Cat-5 cable connects to the pressure sensor.

Power/Motor wiring:

WireDescription
Red+12 Volts
BlackGround
RedPump motor +
GreenPump motor -

Power considerations

The black and green wires are in pairs of 20 AWG wire. There are four red wires all connected together. The connections are doubled for higher current capability needed by some of the larger automotive pumps.

The MOSFET that switches the pump on and off includes a heat sink tab. A heat sink with good air flow is recommended, particularly for large high current pumps. If you can comfortably keep a finger on the heat sink tab while the pump is operating, the heat sink is sufficient. If you feel the MOSFET getting warmer than you like, bolt the tab to a larger piece of aluminum. It is even possible to use a strip cut from a common aluminum can if a commercial heat sink is not available. Make sure the heat sink is not in an enclosed container and there is plenty of air flow.

In all cases, avoid connecting the heat sink tab to chassis ground or any voltage source. This could damage the MOSFET.

Sensor wiring:

FP 1.1 harnessDescriptionBosch 4-pin SensorFord 3 pin sensorAEM sensor2006 Ford Focus harness
Blue/White+5 Volts21RedGreen/Yellow
Blue, Brown, GreenGround42BlackGreen/Orange
Brown/Whitefuel pressure signal13GreenGreen/White
Green/Whitefuel temperature signal3No connectionNo connectionOrange/Gray

Normal operation

When properly connected, the LED will flash twice indicating proper operation. If there is no fuel flow out of the system, e.g. injectors are closed, the pump will pressurize briefly (100 ms or less). If the pump continues to run, check for leaks, FRP sensor connections, or low battery voltage. If the pump does not run at all, check pump connections and FRP sensor connections.

Pressure adjustment

There are two buttons, one for pressure increase the other for pressure decrease. Each press changes pressure by a little less than 1/4 PSI. It is initially set to 43.5 PSI. To reset pressure to 43.5, hold the UP button for a few seconds. The LED will blink three times indicating it's back to 43.5 PSI.

Success stories

You read can about fuel pump controller success stories of other installations.

FAQs

What does a fuel pump controller do? ›

The Fuel Pump Driver Module controls the voltage delivered to a vehicle's fuel pump. By controlling the voltage, the module maintains optimal fuel pressure and fuel delivery to the engine throughout its full operating range.

How do you manually test a fuel pump? ›

So you get your black test lead put it on the pen for the ground. And you can use the red test lead

What sensors control the fuel pump? ›

To shut off the fuel pump in the event of a stall, the PCM on some imports must “see” an engine running signal from the air flow sensor to maintain fuel pump operation. On all other vehicles, the PCM must see a valid signal from the crankshaft position sensor to keep the fuel pump activated.

How do I test if my fuel pump is failing? ›

To confirm that your pump has failed, check the pressure in your fuel lines with a fuel pressure gauge; if it reads zero, then your pump is likely dead. You can also check your car's fuse box; a blown fuel pump fuse is another reliable symptom of a failed pump.

How do you reset a fuel pump control module? ›

The fuel pump shut-off switch has a red reset button on top of it.
...
Should your vehicle shut off after a crash, you may restart your vehicle:
  1. Switch off the ignition.
  2. Switch to start position.
  3. Switch off the ignition.
  4. Switch on the ignition to re-enable the fuel pump.
  5. If vehicle does not start, repeat steps 1 through 4.

How much does it cost to replace a fuel pump control module? ›

The cost of an aftermarket fuel pump driver module replacement can range between $100 to $550 for parts alone. Several factors affect pricing, such as brand and warranty. Labor can cost you an additional $125 to $300, depending on the rates in your area.

How do you fix a fuel pump without replacing it? ›

How to fix a fuel pump without replacing it?
  1. Use Fuel Pressure Gauge. This can be one of the best alternative solutions when you are concerned with the various ways to deal with a bad fuel pump to start your car. ...
  2. Applying Some External Pressure. ...
  3. Maintaining The Engine's Heat.

How do you check a fuel pump without tools? ›

How to Tell if BAD FUEL PUMP with NO TOOLS - YouTube

What are the symptoms of a weak fuel pump? ›

Is My Fuel Pump Going Bad? Here Are 8 Signs It Is!
  • Fuel Tank Noise. A damaged fuel pump might make a loud, whining sound that you'll hear from your gas tank. ...
  • Difficult Starts. ...
  • Sputtering Engine. ...
  • The Actual Stall. ...
  • Power Loss. ...
  • Surging Power. ...
  • Lower Fuel Efficiency. ...
  • Dead Engine.
1 Jul 2020

Can ignition switch cause no power to fuel pump? ›

If the ignition relay shorts, burns out, or otherwise fails while the engine is operating it will cut off power to the fuel pump and ignition system. This will cause the vehicle to immediately stall due to fuel and spark being cut off.

What sends power to the fuel pump? ›

The fuel pump relay sends a current to the electric fuel pump. A fuel pump relay is an electrical device much like an automotive fuse. It directs current to the electric fuel pump and ensures that the part receives enough power to operate properly, but not too much as to damage it.

How do I know when I need a new fuel pump? ›

Seven Signs Your Fuel Pump Is Going Out
  1. Sputtering Engine. Your fuel pump is telling you something if your engine starts to sputter once you've hit the top speed on the highway. ...
  2. Overheating Engine. ...
  3. Low Fuel Pressure. ...
  4. Power Loss. ...
  5. Surging Engine. ...
  6. Gas Mileage Decrease. ...
  7. Dead Engine.
10 Mar 2020

How do I check my fuel pump pressure without a gauge? ›

The best way to measure fuel pressure without a gauge is to use an OBD II diagnostic scanner tool. This will give you real-time engine fuel pressure readings, directly from the fuel pressure sensor. The safest method of checking the fuel system on a vehicle these days is by using an OBD diagnostic scanner.

Where is the fuel pump fuse located? ›

In most car models, the fuel pump relay is located in a fuse box somewhere under your dashboard, but it can also be located in the fuse box in the engine bay. The engine's or the dashboard fuse box is usually a long black box containing a fuel pump relay and various other fuses and relays.

How do I reset my fuel sensor? ›

Press and hold the "Trip/Odo" button again until the Odometer says "1." This means that the reset process has begun. Keep holding the button down while the fuel gauge resets. Release the "Trip/Odo" button once the reset is complete. You'll know the process is finished when the Odometer display moves back to normal.

Is there a fuse for the fuel sensor? ›

Along with the electrical connections, the fuel gauge also utilizes a fuse. You can find the fuse in the box located under the steering column or on the driver's side of your vehicle. In some vehicles, there is also a fuse box under the hood.

Where is the fuel pump inertia switch? ›

In the event of an accident, an inertia switch may trip, isolating fuel pump operation. Once the switch has tripped it must be reset before attempting to restart the engine. The inertia switch is located behind the trim on the left-hand side of the vehicle, forward of the front door post, below the fascia.

How long does it take to replace a fuel pump module? ›

It takes about two to three hours to complete the job. Depending on your make and model of vehicle, it can be quite a challenge. If you're not confident in changing it yourself, it's best to take it to a mechanic.

How many years does a fuel pump last? ›

Because of the important role they play, fuel pumps are meant to be tough and withstand almost the entire life of your car. You typically don't have to replace your fuel pump until you have at least 100,000 miles on your vehicle, and fuel pumps have been known to last more than 200,000 miles!

Can I replace a fuel pump myself? ›

Replacing the fuel pump isn't hard, per say. If you follow the right guide, or get the owner's manual, and follow it step by step, you'll be able to do the repair. It's completely possible to do with hand tools.

What causes a fuel pump to stop working? ›

The top reasons for fuel pump failure are contamination, overheating, and the gears in the the fuel pump wearing out over time. Rust, debris, and dirt are three common particles that can somehow enter the gas tank and be fed towards or through the intank fuel filter and possibly into the fuel pump.

What will stop a fuel pump from working? ›

The most common cause of fuel pump failure is frequently running the tank low on fuel, which causes the motor to overheat. The second most common cause is fuel contamination, usually dirt and rust particles that clog the fuel strainer and prevent the pump from drawing enough fuel under high engine load.

What happens if fuel pressure regulator is stuck closed? ›

When the fuel pressure regulator gets stuck closed, it will cause more than needed fuel to enter the combustion chambers. The combustion of too-rich fuel results in black smoke which is released through the exhaust pipe.

Would a bad fuel pump throw a code? ›

Bad Fuel Pump, Fuel Pressure Sensor Can Trigger 'Check Engine' Light, P0087 Code. Your car's “Check Engine” or “Service Engine Soon” light can flash on for more than 1,400 different reasons.

Why does the gas pump keep stopping when my tank isn't full? ›

So Why Does It Keep Shutting Off? The shutoff mechanism is primarily designed to shut off the fuel pump when your gas tank is full. It shuts off the fuel supply in this situation because it would be a fire hazard if your vehicle's gas tank overflowed and spilled all over the ground, and the person holding the nozzle.

How do you clean a clogged fuel pump? ›

How To Clean Your Motorcycle Fuel Pump | MC Garage - YouTube

What are the symptoms of high fuel pressure? ›

Symptoms of High Fuel Pressure
  • Check engine light.
  • The exhaust gives off fuel smell.
  • Low fuel economy and constant refuelling.
  • Poor engine performance.
  • Blackened spark plugs.
  • Spark plugs that are wet with fuel.
  • Restrictions in return line.

What does a BMW fuel pump control module do? ›

The electronic fuel pump control module (EKPS) controls the power to your BMW fuel pump. EKPS control unit is a different component from the fuel pump. The EKPS unit is usually located in the trunk, side panel or under the rear seat while the fuel pump is mounted on top of the fuel tank.

What sends power to the fuel pump? ›

The fuel pump relay sends a current to the electric fuel pump. A fuel pump relay is an electrical device much like an automotive fuse. It directs current to the electric fuel pump and ensures that the part receives enough power to operate properly, but not too much as to damage it.

Does ECU control fuel pump? ›

Electronic Control Unit (ECU)

It uses engine RPM and signals from different sensors to meter the fuel. It does this by telling the fuel injectors when and how long to fire. The ECU often controls other functions like the fuel pump and ignition timing.

How do you fix a fuel pump without replacing it? ›

How to fix a fuel pump without replacing it?
  1. Use Fuel Pressure Gauge. This can be one of the best alternative solutions when you are concerned with the various ways to deal with a bad fuel pump to start your car. ...
  2. Applying Some External Pressure. ...
  3. Maintaining The Engine's Heat.

Where is the fuel pump driver module location? ›

Modified Fuel pump driver module (FPDM) vs stock. What is ... - YouTube

Does BCM control fuel pump? ›

The reason is that the BCM feeds inputs into the Passlock (or other security system) for it to 'determine' if it is being stolen or hotwired. For example: the status of the doors, interior lights, trunk status, etc. and in some cases can even control the fuel pump.

Does fuel pump module assembly include fuel pump? ›

Fuel Pump Assembly Layout. The fuel pump assembly in a vehicle is responsible for sending the required amount of fuel at the right pressure and time to the engine. The assembly consists of a few key parts such as the screen filter, fuel pump and fuel pressure regulator.

Can a bad ignition switch cause no power to fuel pump? ›

If the ignition relay shorts, burns out, or otherwise fails while the engine is operating it will cut off power to the fuel pump and ignition system. This will cause the vehicle to immediately stall due to fuel and spark being cut off.

Can I wire my fuel pump straight to battery? ›

A fuel pump can run directly to a battery in some cases, but it is not recommended. Fuel pumps are designed to run off of the electrical system in a vehicle.

What can cause a fuel pump to not get power? ›

There are several causes why the fuel pump is not getting power. These include faulty or broken wires(connectors), bad ECU or PCM systems, a bad fuel pump relay, or a blown fuse. If such issues are with your car's fuel pump, the electric motor won't function to drive the fuel pump.

How does the PCM control the fuel pump relay? ›

The fuel pump relay is controlled by the PCM by providing the relay with a ground. The PCM chooses to turn the relay on when it sees the motor is running. If the PCM doesn't see an indication of the motor running, it will not supply a ground path to the relay and the fuel pump will not receive power.

What sensor controls the injectors? ›

The injector control pressure sensor detects the pressure of the fuel feeding the injectors, and sends that signal to the computer so that it can make the adjustments for optimum performance and efficiency.

What controls the fuel injector pulse? ›

A fuel injector firing

The amount of fuel supplied to the engine is determined by the amount of time the fuel injector stays open. This is called the pulse width, and it is controlled by the ECU.

Can you fix a fuel pump by yourself? ›

Should you do the job yourself? Installing a fuel pump can be difficult – especially if you've got a full gas tank. Plus, because fuel is flammable, the task can be dangerous. If you decide to tackle the job yourself, make sure to take the necessary precautions and have a fire extinguisher on hand.

How does a car act when the fuel pump is going out? ›

Difficult Starts

If your vehicle's fuel pump cannot get gas from the tank to the engine, you will have trouble starting your car. The car will struggle to start and run because the pump cannot push enough gas through. A worn pump loses its pressure and the engine is being starved of gasoline.

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