Fuel pressure regulator, if bad, what symptoms?

Status
Not open for further replies.
Hard starting...stalling and the smell of raw gas are symptoms of a bad FPR. May be along the fuel rail.
 
Most systems in approx the last 10 years don't have a fuel pressure regulator but instead have a fuel pressure sensor... These systems regulate pressure by varying the voltage to the pump, vs having a mechanical regulator and constantly running the pump at battery voltage... Plus is there is no fuel return line to the tank and pump supposedly lasts longer as it's only pumping what's necessary, instead of constantly circulating the fuel...
 
Originally Posted By: TFB1
Most systems in approx the last 10 years don't have a fuel pressure regulator but instead have a fuel pressure sensor... These systems regulate pressure by varying the voltage to the pump, vs having a mechanical regulator and constantly running the pump at battery voltage... Plus is there is no fuel return line to the tank and pump supposedly lasts longer as it's only pumping what's necessary, instead of constantly circulating the fuel...

My understanding is that returnless systems are an answer to recent EVAP regulations: Returnless systems lack a return line, which eliminates a line and lot of connections, all of which are potential sources of fuel/vapor leaks.

As for the OP's question, I'd expect that most fuel-pressure problems would be very likely to be flagged by the OBD-II system before any symptoms would be felt. I'd be expecting an illuminated MIL with a P01xx DTC.
 
Easy check on vehicles with external FPR mounted to the fuel rail is to remove the vacuum line that is used to work the diaphragm open. If the fuel pressure does not raise once the vacuum line is removed, the pressure regulator is bad.
 
Originally Posted By: ltslimjim
Easy check on vehicles with external FPR mounted to the fuel rail is to remove the vacuum line that is used to work the diaphragm open. If the fuel pressure does not raise once the vacuum line is removed, the pressure regulator is bad.


Or if there's raw fuel in the vacuum line, it's bad.
 
Status
Not open for further replies.
Back
Top