FAQ & Troubleshooting

Fuel Pump

Frequently Asked Questions

In most cases the factory wiring is sufficient to power the DW300-series fuel pump. We do suggest hardwiring any high flow fuel pump when one or more of the following conditions exist.

  1. Your base fuel pressure plus peak boost pressure exceeds 80psi.
  2. Your chassis wiring is more than 10 years old.
  3. You are experiencing a drop in fuel pressure at high load.

The DW300-series pump is designed to operate at up to 100psi.

Yes, the DW300-series fuel pump has been approved for up to 18 volts. Running higher voltage can decrease the life of you’re your pump but does not effect your 3-year warranty.

Our universal kit will work with a wide variety of applications, especially for cars manufactured before 2002. We may be able to provide additional information on your specific car if you contact our tech department.

Yes, for fuel pumps, increasing fuel pressure will DECREASE the flow rate of the fuel pump. A tech sheet showing pressure vs flow of the DW300-series pump accompanies each pump.

Yes, the DW300-series pump was designed and tested with e85 in mind.


  1. Make sure all electrical connections are properly secured (do you hear the pump turn on?).
  2. Make sure you have sufficient level of gas in your tank.
  3. Evacuate any trapped air by priming the pump after installation.
  4. Contact DW technical support.

  1. Make sure the outlet of the pump is properly sealed in the fuel pump assembly.
  2. Make sure your pump is receiving proper voltage under full load.
  3. Make sure sock (pre-filter) is in the proper location near the bottom of the tank.
  4. Contact DW technical support.

Fuel Injector

Frequently Asked Questions

  1. DW injectors are designed to fit the OE manifold and fuel rail. The use of aftermarket fuel rails and manifolds may cause some fitment issues.
  2. Make sure all injector parts are intact and undamaged.
  3. Make sure to lubricate the o-rings with the included o-ring lube.
  4. Make sure no OE parts from fuel rail or manifold are missing (spacers).
  5. Contact DW technical support.

All characterization data of DW fuel injectors is collected and calculated in-house.   The process involves collecting and analyzing over 450 data points on 4 standardized fuel injectors representative of the specific injector part number being tested.  All data is collected in-house via calibrated digital turbine flow meters and fully programmable injector drivers.  Testing procedures are performed in accordance with SAE J1832.  Our offsets are calculated via linear regression from 5 different pulse widths, 4 different voltages,  and 4 different pressures.  Data between the tested voltages and pressures is interpolated.

Application specific data is obtained by formatting the general characterization data into the parameters required for that specific application.  This data is then tested in-car and values are optimized to account for differences between in-lab and in-car variables.  This optimization process is why sometimes the General Characterization Summaries will differ from the application specific data.

  1. Make sure your fuel rail is fully seated.
  2. Make sure o-rings and seals are lubed and properly installed.
  3. Check for pinches, rips, or tears at lower o-rings and seals.
  4. Contact DW technical support.

  1. Make sure fuel rail is fully seated.
  2. Make sure o-rings and seals are lubed and properly installed.
  3. Check for pinches, rips, or tears at o-rings and seals.
  4. The use of aftermarket fuel rails and manifolds may cause some fitment issues that can lead to a fuel leak.
  5. Contact DW technical support.

  1. Make sure your electrical connector is properly connected.
  2. Make sure the male spades on the injector connector are not bent out of alignment.
  3. Make sure OE wiring harness is in good condition and without frayed, broken or corroded wires.
  4. If an injector sticks upon initial installations, it will usually free itself if allowed to idle for a few minutes.
  5. Contact DW technical support.

  1. This is a rare but serious condition. Shut down your engine immediately.
  2. Check to make sure o-rings are properly installed and were not damaged during installation.
  3. Make sure all injector parts, including the plastic pintle caps on the tips of the injectors are intact and undamaged.
  4. Contact DW technical support.

  1. See troubleshooting suggestions above. Any one of these problems can easily go undetected and cause your car to run poorly.
  2. Make sure your car has been tuned properly by a professional.
  3. Contact DW technical support – we cannot tune your car but we can help trouble shoot some other problems that are not listed in this document.


The injector flow rate you need depends mostly on the number of injectors your engine requires, the amount of power they will need to support, and the type of fuel you will be using. There is a calculator on the resources section of our website to help you choose the correct size. In addition, our tech and sales staff or your tuner can help you choose the best size for your build.

Cobb-spec injectors are available for some Subaru applications and sizes. These injectors are made to work for specific downloadable Access Port tunes. If you are not using one of these specific tunes, you do not need to order Cobb-spec injectors.

Yes. Anytime you install larger than stock fuel injectors into your car, some sort of tuning (flash, piggy-back, stand-alone, etc.) will need to be performed for your car to run properly.

DW injectors are designed to be a drop-in fitment replacement for the OE injectors. This does not always mean they will look exactly like the OE injector. The DW injector may have a different color, different shape, or even a different total length. However, in regards to fitment, they will fit the same as the OE injector.

DeatschWerks does not modify injector flow rates as a service. Purchasing our high flow injectors is more economical, more convenient, and more reliable than modifying your OE injectors.

The majority of injectors are top feed. Top feed injectors sit under the fuel rail and side feed injectors fit inside the fuel rail. Side feed and top feed injectors cannot be interchanged unless a fuel rail conversion is performed.

The majority of injectors are high impedance. Low impedance (peak and hold) injectors have a resistance of between 2 and 4 ohms. High impedance (saturated) injectors have a resistance of between 10 and 14 ohms. Low impedance and high impedance injectors cannot be used interchangeably.

Latency is a measure of the amount of time it takes for an injector to fully open once it receives its signal to fire. It is usually measured in milliseconds or microseconds and is an important parameter when tuning. We include latency data on our flow report for most applications.

Yes. For fuel injectors increasing fuel pressure will INCREASE the flow rate of the injector. All DW injector flow rates are calculated at 3 bar (43.5 psi) of pressure. Although DW injectors are able to operate at pressures in excess of 100 psi, we suggest a base pressure of less than 60 psi to allow for easier tuning, optimized spray patterns, and increased reliability of your entire fuel system. There is a calculator on the resources section of our website that will calculate your injectors’ flow rate at different pressures.

Delta pressure is the difference between the rail pressure and the manifold pressure. Delta pressure is the actual pressure that the fuel injector is subjected to. In most applications, it is maintained at a set point by a fuel pressure regulator that is referenced to the manifold.


415 E Hill Street
Oklahoma City, OK 73105
Phone: 1.405.217.0701
Toll-free: 1.800.419.6023
Fax: 1.405.217.0700