EFI Fuel Pressure Gauge
Assuming correct fuel
pressure can cause you to waste a lot of time and money.
You
might be trying to get an engine started, or find a problem with a
running engine. Everything appears to be working correctly,
but
either the engine will not start, or it will idle OK, but cofffs and
splutters when the trottle is applied.
A quick check of a simple Fuel Pressure Gauge, can show up a problem with a fuel pump or fuel pressure regulator.
You
might be trying to get an engine started, or find a problem with a
running engine. Everything appears to be working correctly,
but
either the engine will not start, or it will idle OK, but cofffs and
splutters when the trottle is applied.A quick check of a simple Fuel Pressure Gauge, can show up a problem with a fuel pump or fuel pressure regulator.
EFI Fuel Pressure Gauge: 0 to 100 PSI Range
Normal
fuel
pressure in an electronic fuel injection system can range from 20PSI to
80PSI, although these two numbers are the extreme.
Hence, a Fuel Pressure Gauge designed for use on an EFI system should have a 0 to 100PSI range.
Hence, a Fuel Pressure Gauge designed for use on an EFI system should have a 0 to 100PSI range.
Diagnostics - Fuel Pressure Very Low (less than 10PSI)
There are three main
causes of such low fuel pressure:
- Out of Fuel. I know it sounds simple, and it is. But this is the most common reason for low or zero fuel pressure. A note on this. If you do not have a Fuel Pressure Gauge on the engine, you may end up spending a lot of time trying to work out why the engine will either not start, or will start and idle, but it will not rev up. So, check that you have fuel in the tank!
- Failure of the Overpressure Return Valve in the Fuel Pump. Most fuel pumps have a safety mechanism to prevent massive fuel pressure in the event of a fuel line blockage. In many pumps this valve opens at around 80PSI. But, if this valve fails, the engine may have a similar symptom to point 1 above.
- Fuel Pressure Regulator failure. If the fuel pressure regulator fails, the fuel pressure may not drop dramatically at idle, but it may drop off as fuel demand increases.
Diagnostics - Fuel Pressure Very High
A Fuel Pressure Regulator
is designed to hold fuel pressure across the injector so that the fuel
is delivered correctly.
If there is a blockage or a kink in the fuel return line, the fuel pressure in the fuel rail can increase greatly. This can lead to problems ranging from the engine running richer than was intended to tuning difficulty, especially at idle and cruise.
If there is a blockage or a kink in the fuel return line, the fuel pressure in the fuel rail can increase greatly. This can lead to problems ranging from the engine running richer than was intended to tuning difficulty, especially at idle and cruise.