Frequently Asked Questions (FAQ)

Q: What pressure should my pump be running at?

  • Duramax engines 8-10 psi
  • Cummins engines
  1. ’89-’93 6-8 psi
  2. ’94-’98 16-18 psi when supplying factory lift pump.
  3. ’94-’98 45 psi when supplying direct to P-7100
  4. ’98.5-present 16-18 psi
  • Ford Powerstroke
  1. ’99-’07 55 psi
  2. ’08-’10 8-10 psi
  3. ’11-present 55 psi
  • Majority of class 8 units will be preset at 16-18 psi

Q:  What filters do I need for my unit?

  • Click Below for Filter Cross References:
  1. HD Series
  2. Titanium Series (Gun Metal Grey Color)
  3. Titanium Series (Old Style Blue Color)
  4. Platinum Series
  • NOTE**All 95/Titanium Series units with a FF-2003 fuel filter will need P/N FSN-2001 installed in order to use the FWS-3003/cross reference.

Q: I just changed my filters, how do I prime my unit?

  • Click Below to Watch "How to Prime a FASS System" Instructional Video

Q: My pump no longer turns on when the key is turned to the run position, what’s wrong?

  • Check for a blown fuse in the FASS wire harness
  • Using a multimeter, check to make sure relay is working properly. Terminal number 85 should have 12 volts when the key is turned to the run position. On  ’98.5-present Dodge Cummins, the engine will need to be turned over with the starter one revolution to check for 12 volts at terminal 85.
  • Using a multimeter, check for 12 volts at the electrical connection at the FASS unit.

Q: My unit is very loud, what’s wrong?

  • A loud pump can be caused by several issues. Clogged filters will cause the pump to cavitate and become loud. If a restriction is present on the suction side of the fuel pump there will be excessive cavitation which will cause the noise of the pump to increase. Majority of the time a restriction on the suction side of the pump will be a clogged screen on the bottom of the fuel module inside the fuel tank. Excessive pressure could also cause the unit to over amp and become loud. A fuel pressure gauge will be needed to determine the pressure.
  • Click Below to Watch our "5 Gallon Bucket Test" Instructional Video

Q: When my fuel level is below a ¼ tank, I run out of fuel or my fuel pressure drops to 0 psi, why?

  • If your unit is not equipped with a STK/sump bowl, the factory fuel module supplies the FASS pump. Factory fuel modules are equipped with a filtering screen which, over time, can become clogged by the contaminates found in diesel fuel. When the fuel level starts to go down to ¼ tank and below fuel can’t enter the basket from the top anymore. If the screen is clogged and not allowing fuel to enter, the FASS pump will empty this basket before it can refill causing the truck to run out of fuel.

Q: I have a ’98.5-’02 Dodge Cummins and after the truck has reached operating temperature and I shut the truck off, I have a long crank time before the truck will start again, why?

  • The VP44 injection pump is equipped with a diaphragm and this diaphragm can develop a crack in it which will allow fuel to seep past it during start up. This issue is not necessarily from high fuel pressure. For testing procedures and solution please refer to page 26 of the troubleshooting guide.
  • Click Here to view the FASS Technical & Troubleshooting Guide

Q: My truck is stock at this time but I plan to do upgrades in the future, will too large of a pump hurt my truck?

  • Yes and no. To a point you can have more flow than you need but you DO NOT want excessive pressure. Many customers choose to purchase a 150gph pump for the stock/mild upgrades because the price difference between the 95gph and 150gph is so little. This is fine as the pressure will still be at the recommended pressure for your vehicle. Having a pump that is larger than 150gph on a stock or slightly modified truck can cause issues. Vehicles that actually need larger units are mainly purpose-built competition vehicles and can handle higher pressures. Along with other competition specific parts, these pumps are going to be much louder. Performance of the motor will produce added pressure which will create more amp draw and lessen the electric motor life. Please select the correct unit for your application. If you are unsure please give our tech line a call.
  • Click Here for our List of Customer Service Contacts.