2004 V70 2.4L NA P0089. Fuel pressure oscillates then drops to zero.
 

I have a 2004 Volvo V70 with the non-turbo 2.4 Liter 5 cylinder engine. It has the metal gas tank (so no serviceable fuel filter). It was intermittently stalling or refusing to start but would typically restart after a few tries. I read an OBD II code P0089 - Fuel Pressure Regulator 1 Performance, and the Volvo code ECM-261A Fuel Pressure system; Faulty signal // can be from fuel pressure or MAF.

I replaced the fuel pressure sensor with a Bosch 0261230109 unit and the car seemed to work OK for a few days. Now the problem is worse than before and the P0089 has come back. If I attach an analog fuel pressure gauge it will oscillate between approx. 44 psi to 78 psi rapidly, maybe at 2 Hertz. My Autel scanner agrees with these values. Earlier today I let the car idle a while and it just continued to oscillate. I shut the engine down for 1/2 an hour and pressure held at almost 40 psi.

Later I tried to drive up and down my driveway and the car stalled as fuel pressure ramped down to zero. I repeated this a few times, fuel pressure live data will oscillate in the 40-80 range then ramp down to zero over a few seconds.

I will probably try to disconnect and examine the PEM next unless anyone has any strong opinions about the symptoms listed. Has anyone seen a bad fuel pump that can output 40-80 PSI then just drops to zero? Has anyone got a bad fuel pressure sensor from Bosch? I think the PEM is attached to the top of the metal fuel tank and this is a rust/salt/snow belt car so it may have issues.

PEM seems to have solved the problem
 

I went ahead and purchased a used PEM for $60 from a salvage yard. There is a good video, "volvo s60 fuel pump pump electronic module pem location", on the web which shows how to change the PEM when it is mounted on top of a metal tank. After swapping the PEM fuel pressure seems to be steady at about 54 PSI and the car doesn't stall. This car is a V70 built in Belgium, which is factory no. 2 in the VIN number, which may explain the metal fuel tank.

hello, I was hoping you could explain what a PEM is for me. I have the same engine and i too am looking for a cure. thanks

Sorry, did not see your post. The PEM is the fuel pump driver module. On the Belgium built 2004 V70 with a metal tank it was P/N 30769225. I think the earlier Volvo's used engine vacuum to a fuel regulator mounted underhood on the end of the fuel rail. This car has a fuel sensor that must work with the engine computer or maybe just the fuel pump driver module.

The V70 had the PEM sitting on top of the fuel tank with a single bolt and clip to hold it there. It gets abused by winder road salt and moisture. I bought a used unit from a later vehicle, when Volvo began putting the PEM inside the trunk or elsewhere in the interior.