Alessio Randazzo

Hi I’ve been having a problem with my mustang. It’s been shaking at idle and sometimes it’s really hard to start. I checked the fuel pressure and it’s only getting 10psi at idle. How do I go about fixing this issue?

imp

What year and engine? 10 psi is way low, as your symptoms show. Has the fuel filter been changed? If it's clogged, the pressure needed is being wasted across the filter media. Need to know what type of fuel system (year) is present. If return-type, the fuel pressure regulator may be faulty, stuck open, allowing all the fuel to return to the tank, leaving none to run the engine. If returnless type, the fuel pressure and temperature sensor may be faulty; that would be an OBD-II (On Board Diagnostics II) design, and trouble codes would be present. Lastly, if nowhere else left to check, suspect the fuel pump.

Alessio Randazzo

It’s a 2002 mustang gt and I replaced the fuel filter already and it didn’t fix it. You think it’s the regulator ?

Alessio Randazzo

Or does the 02 gt have a returnless?

imp

That I can't answer, as I don't know. But a 2002 will surely throw a trouble code for the Fuel Pressure (and Temperature, if it's the early returnless) Sensor which will give a clue as to what's wrong. The computer has no way of judging a failing fuel pump, however, only whether it is drawing electrical power or not.

Look for the fuel line which comes from the tank, up into the engine compartment. Not sure where it is on '02, but if you find the line coming from the filter you can trace it all the way up into the engine compartment. If it's a return-type, there will be a second fuel line usually located near or next to the supply line. Depending on engine type you may be able to see the connection(s) of the fuel supply and return line right at the fuel rail on top of the engine. The fuel return line carries the fuel back to the tank, controlled in amount by the pressure regulator. The regulator is an easily replaced part. But, you don't know if the pump is at fault. Pump replacement is far more costly and time consuming than regulator replacement.

Try to check for codes. Any auto parts store will do it free, if the vehicle can be brought there.

Alessio Randazzo

I found that my car has a returnless style fuel system. The check engine light has came on once but it went away the next day. Do you think this means my fuel pressure sensor went bad?