Test 1 - Citroen Xantia 2.0 HDi Fuel Filter / Primary Pressure Regulator Home Test. P0230 Fault

I am getting fault code P0230 (Primary fuel system fault). The engine warning light comes on and the engine runs rough with erratic idle and sometimes won't run above 2,000 or 3,000 rpm particularly up hills. Sometimes the light is off for several journeys and it runs ok! The Fuel filter housing should regulate the pressure produced by the electric pump in the fuel tank. When the pressure gets to 2.5 Bar (37 psi) a valve should open allowing fuel to return to the tank. When I recently changed the fuel filter I blew through the valve (the smaller of the 2 outlets on the top of the filter) and got the idea that it was always open. This is my "simple" test to check the regulation pressure. I have a 1.5m length of 8mm clear tube. (Not reinforced as it needs to stretch to 10mm). One end is blocked with an 8mm drill bit and hose clamp. Disconnect the larger (10mm) outlet from the filter which feeds to the high pressure pump. Connect the open end of the clear tube to the 10mm filter outlet. Turn on the ignition and see how far up the clear hose the fuel goes. (I connected a seperate 12V supply to the pump so I could check the current and run it longer than the 5 seconds it will run each time the ignition is turned on). I have marked the tube "1Bar" half way along the tube (75cm from closed end), 2 Bar 50cm from the end and 2.5 Bar 43cm from the closed end. I was expecting a very low reading but I got just below 2 Bar which is perhaps within tollerance for a valve which is no doubt just a spring and a ball. I think the pressure rise to that pressure looks a bit slow, as if perhaps the pump is only able to produce 2 Bar and the regulator valve isn't opening after all. It also appears that the filter isn't being purged of air, which may be the case if the pressure relief valve isn't opening. So I next check the pump pressure by connecting the sealed off tube directly to the fuel tank pump 10mm outlet. The pressure very rapidly got to over 5 bar and the current got to about 6 Amps. The pressure was maintained for some time after the pump power was removed. This was all very rapid so I couldn't do a video. I then checked the pump flow in my Test 2 video. LATER THOUGHTS - The pressure measured in this "Test 1" video dies away immediately when the pump stops after the end of the video. I think this is probably not normal and may result in the engine & high pressure pump sometimes being cranked over without sufficient pressure in the filter/regulator. Hence the P0230 primary fuel fault code. Looks like I need a new filter housing.

• #autos_vehicles
• #p0230
• #citroen
• #xantia
• #fuel
• #tank
• #pump
• #filter
• #pressure
• #diesel
• #peugeot
• #406
• #306
• #fault
• #code
• #reader
• #diagnostic