Frequently Asked Questions


Q. Why does my fuel pressure vary from one pass to the next?
A. Faulty fuel pressure gauge can cause fuel pressure fluctuation. If your gauge is a few years old, test it. Under-hood heat can affect gauge accuracy. A dirty regulator is also possible, clean it or send it in. You should always set the regulator in a flowing condition. The engine should be running at about 1,700 to 2,000 RPM. Battery low. Check voltage. Low pump pressure. Look for inlet line obstructions such as fuel-cell foam.


Q. Why is my fuel pressure too low, or I have no pump pressure?
A. Check the voltage to the pump, relay switch. Could be faulty. They can be bad without going out. Weak relay reduces voltage. Replace them. Check wiring, look for an improper ground. Check the battery voltage. Check the filter and inlet line for obstructions. Look for leaks on inlet side. Adjust bypass. Is there debris in pump bypass (poppet). The bypass valve could be stuck open. Clean filter. Replace deteriorated fuel-cell foam. If no pressure, the pump may be operating in reverse. Check the wiring diagram. No fuel in fuel cell, or fuel cell improperly vented.


Q. Why is my fuel pressure too high?
A. The return line could be too small. The voltage could be too high. If you need to run the pump at a pressure lower than it is designed for, call us and we’ll send you a special spring. Improperly adjusted bypass. See pump instruction sheet for proper setting.


Q. Why won’t my pump run at all?
A. This is most likely a low- or no-voltage problem. Check battery condition. Check for a bad fuse or bad relay. Look for improper ground. Check diagram, make sure you have wired everything correctly. Check any in-line switches for proper operation and voltage rating.


Q. Why does my pump seem excessively hot?
A. Note that normal operating temperature can reach 137 degrees Fahrenheit (58 degrees Celsius). Anything below this is OK. If the pump is warmer than this, look for low voltage. If there is excessive pressure, there could be debris in pumping mechanism causing too much load. Check to see if the bypass is obstructed. Check instructions for proper pressure setting.


Q. What could cause my pump to operate noisier than usual?
A. Aeration, or air in the system, can cause excessive noise. Check for poor inlet side sealing, check O-rings, fittings, damaged sealing angles on fittings. We recommend rubber isolator between pump and frame mounting surfaces. Mounting the pump solid to the frame of the vehicle can accentuate the noise. If the fluid level in the tank/cell is too low, the pump can suck a vortex and induce air into the system. Check pump mounting brackets for tightness. If the fuel cell return line dumps fuel near the suction line, it can cause air to enter the system also. Keep this return line’s fuel input as far away from the supply line as possible.


Q. What can I do about a leaky pump?
A. Leaks are almost always caused by a worn or damaged pump seal. You need a new one. Return it to the factory. A Seal should be replaced every two years under heavy use, or if it sits unused for a long time. Return the pump to the factory for service. If the pump leaks from vent hole, you need a new seal. Return the pump to factory for service and bench flow testing.


Q. Why does my regulator’s pressure fluctuate?
A. MagnaFuel considers excessive fluctuation to be over 1-1/2 pounds of pressure. Vibration, aeration, faulty gauges, or sharp changes in supply/pump pressure usually cause this. You should isolate the regulator with rubber mounting to tame vibration.


Q. Why am I getting pressure spikes?
A. Poor gauges, too high or too low pump pressure, or sharp drops in system pressure could cause large pressure spikes at the regulator.

Q. Why does my fuel system pressure seem to drop throughout the day?
A. Heat can effect liquid-filled gauges. Voltage drop can also cause this problem (battery, ground, connections, and incorrect wire gauge. Avoid mounting fuel system close to heat sources.


Q. Why does my car seem to slow halfway through a quarter-mile run?
A. Not enough fuel volume. If it falls off in high gear, it is a pump volume issue; pump may be too small. If it falls down during launch, it is a fuel-pressure issue.


Q. Why does my regulated pressure seem to creep higher and higher or go to full pump pressure?
A. Debris in fuel system has contaminated the valve-to-seat seal. Disassemble per regulator exploded view. Wash with brake cleaner or similar cleaner and reassemble. Be sure you reassemble correctly. CAUTION: Do not over-tighten cartridge. Check fuel filter. Make sure to flush lines before using a newly installed fuel system. A common problem of new systems when there is debris left over from cutting fuel lines and other installation trash.


Q. Why is my regulator noisy when I first start the engine?
A. Vibration or chatter is common when then engine is first started due to air in system. This is amplified due to the metal-to-metal valve/seat assembly. Should go away in less than a minute. Regulators used for Nitrous are “dead-headed” to the solenoid. MagnaFuel suggests you use an air-bleed system to purge trapped air from the system.