Low fuel pressure 2006 XC70

jgadbois · Post by **jgadbois** » 01 Apr 2021, 18:12

Bought car a few months ago. Shortly after started getting P0089 codes. Changed fuel pressure sensor and tried a different pump module. No help. Pump utilization in mid/upper 50's. Changed pump.

Last week driving home engine started bucking, lost power and died. Restarted engine and everything fine. Happens 5 more times on way home.

Today connected up DICE and a fuel pressure gauge. Luckily after about 15 minutes symptoms occurred. Pressure in VIDA and on gauge dropped to about 100 Kpa with 85% pump utilization. Stopped engine and restated. Everything normal.

I'm guessing clogged intake on pump or electrical signal to pump module dropping out. Any help on how to proceed would be greatly appreciated.

John

Post by **abscate** » 02 Apr 2021, 03:37

The weak spot on an aged P2 seems to be the Pump electronic module or PEM

Its an expensive part so a junkyard swap to test is a good approach. I have a couple of used ones here if you want to try test one, would fit in the small usps box

You can open them up and clean out the aluminum oxide which tends to kill them, too, if you want to swap cash for time

jgadbois · Post by **jgadbois** » 02 Apr 2021, 06:17

Thanks for the generous offer. I replaced the PEM in my initial troubleshooting with a used unit. I have since swapped back and forth between them to no effect.

Since shutting off the ignition and immediately restarting always works I am leaning toward an electrical problem.

Post by **oragex** » 02 Apr 2021, 07:19

Do you have the external fuel filter ? Another particular issue with the pump on plastic fuel tanks is the pump has the long hose attached at the bottom, when a new pump is lowered inside the tank, the hose may kink right under the pump. But in theory it would cause a permanent fuel starvation. Was the second float on the left side of the tank checked so it didn't get clogged where it gets the fuel into the long hose in between the tank sections ? May as well inspect the fuel hoses under the car and the connection near the engine intake

jgadbois · Post by **jgadbois** » 02 Apr 2021, 12:13

Yes to external fuel filter. I've changed it twice since this started, it did not appear to be clogged. I will be pulling the fuel pump again when the amount of fuel in the tank gets close to empty.

I am really thinking electrical because when I was testing I turned the ignition off then on in the space of about 1 second and the pressure in Vida went from 100kPa to 400kPa immediately. If it were a clog on the intake to the pump I would expect to see something in the fuel pressure readings but it returned to normal immediately.

Caddersv · Post by **Caddersv** » 30 Oct 2025, 12:01

Did you ever get to the bottom of this? Symptoms are the same as mine

Post by **vtl** » 01 Nov 2025, 08:33

Sensor values jumping all over the place can be a bad reference voltage.

I've battled with hard starts and occasional system cutouts while starter is cranking. Turned out to be a heavily corroded positive connection on the fuses box, the one that connects battery, starter, alternator and all the electronic modules with one stud and nut. When it corrodes, the resistance raises immensely, the starter is not receiving enough amps from battery and brings the system voltage below 10.5 V, which triggers cascade of glitches in electronics. A lot of wire brushing and contacts cleaner and the problem is gone.

If the car is not dying under high load (accelerating super hard on highway), it means it gets enough fuel, so look elsewhere.