Here is how I diagnosed and fixed P0087 Fuel rail/system pressure too low on my 1.6 THP.
Problem: Cold start was very rough, seemingly running on 2-3 cylinders, spitting unburnt fuel from the exhaust, then cooling fans running amok, orange light and "get your engine repaired".
The fans running wild is very annoying. Typically I would disconnect the battery to stop them and tell the car it was to be shot. Disconnecting the battery clears the orange light and codes. Starting it again would, seemingly, be ok, problem gone. It would also be ok when warm. When cold starting I could also keep it at 2000 revolutions for 30-40 seconds. It would stabilise and seemingly be ok afterwards.
The codes would be P0087 alone or with P1336 crankshaft sensor, P1338 misfire cylinder 2 and P1340 misfire cylinder 4. Being ok when warm is not typical of coil failure. Coils tend to fail when warm on heavy load. So P0087 could be the prime problem and the pump the prime suspect.
Internet advice being what it is, particularly when you ask for code advice, was still worth trying. I found a French shop www.chrisgas.fr where the videos seemed unusually clear and thorough. P0087 with the other three is typical of a failing high pressure pump.
The pump has a membrane in an external housing, a cup, where you can measure the position of the membrane..The distance from the top of the housing to the membrane increases with use. 22mm is new. 26-27 is end of life. Checking it is easy and can be done with the pump in place.
The pump is at top of the engine and access is only a few minutes, just remove the plastic inlet ducts, be gentle. The membrane housing, a small cylinder, faces downwards, and using a vernier calliper to measure it would require some magic. I put a match in a small piece of cardboard (photo) and measured it afterwards, 27mm. I wonder how the poor engine had run at all.
- Improvised vernier calliper.
The vernier calliper confirmed 27mm. The date on the pump corresponded with the car, which has done 263000km.
A new pump is 1000 quid. Chrisgas proposes refurbishing it at a quarter of that, so I used an address inside the EU and sent it off. He gave the real quote (same as on the website) when he had dismantled it and confirmed that it was serviceable. Very nice videos of the work was provided, with his very nice local French accent.
The output line connection is threaded directly in the aluminium pump housing, so make sure the threads are totally clean and be very careful. I screwed it in, fingers only, before I put the pump fully in its recess in the engine. Then some sellotape will keep the three screws from escaping, the inlet line has a standard connector. Let the fuel pump in the tank bleed the pump: Loosen the connector before tightening it again, ignition on. There will be air with petrol so do not forget the rag.
The car was happy from the first start.
- Improvised vernier calliper.
