Wifes 08 2.8t threw code p0089

[Turbo00]

Code was P0089, fuel pressure regulator. Through some quick research, this is somewhat common, sometimes related to gas cap, but also related to a failing fuel pump. Car is still under the 5 year/100k mile drivetrain warranty (2008 w/49k). Any thoughts? What I've heard regarding GM servicing the pre-2010's is that you have to take it to a GM/Saab dealership, true?

Shit timing of course. Thanks in advance.

[Turbo00]

So, the code cleared itself this morning but we took it in to a local place anyway. FYI - fuel system isn't covered by powertrain warranty. Fuel pump tested in spec, and they said they see a lot of these codes as false positives when the tank is nearly empty as hers was, especially in the winter. Note to self, stop letting cars get below 1/4 tank, and keep fingers crossed that it really isn't the pump.

[DrewP]

I'm going to put my answer here in case it helps anyone out in the future:

Originally Posted by Turbo00

Hey Drew - saw a thread you started regarding P0089 on a 2.8T a while back. My wife's car is doing the same, code went off yesterday, filled the tank, drove 50 miles, came back on, but its driving fine - no limp mode etc. Betting it's the fuel pump, but just wondering if you came across anything. Does the tank have to be dropped to access the pump? Wondering if I can replace it myself. Thanks!

The description for P0089 is "Fuel pressure regulator, performance problem."

The B284 does not have a mechanical fuel pressure regulator - it uses a variable speed pump with no return line to increase the fuel pressure with increasing boost. When air mass increases, the ECM commands the pump to spin faster, generating more pressure. Boost goes back down, pump spins slower and lowers pressure.

There is a fuel pressure sensor mounted on the fuel rail towards the belt side of the engine, in the valley between cylinder 1 & 2. It's a little black plastic rectangle, about 1" square.

P0089 is set when there is a certain percentage difference between the ECM's 'commanded' or 'requested' fuel pressure, and the actual pressure as reported by the sensor.

It has nothing to do with the fuel filler cap or EVAP related problems. Usually what sets from a low fuel level related problem is a code for 'Misfire with low fuel level," I think the GM standard code for that is P1460, the generic is maybe P0313.

The problem could be the pressure sensor reporting incorrect pressure - the sensor is cheap, usually worth replacing it as a matter of course to see if the code returns.

If the fault returns with a new sensor, there is a fuel pressure test procedure that's done with the Tech2 - it commands varying fuel pressures and you connect a mechanical guage to the rail to check that what shows in the sensor is actually what's being delivered.

The pump is mounted to the top of the tank as an assembly - there is currently no easy way to replace only the pump insert, the entire assembly has to be replaced. List price last I checked for the V6 pump assemblies was in the $630 range.

The lock collar on the V6 tanks is metal instead of the early plastic ring, and they are on REALLY damn tight, you usually need a helper to hold the tank still to get the ring unlocked. There is a little lock catch that you have to depress to unscrew the ring.

You also need the GM-style fuel line quick-disconnect tools to disconnect the feed line that goes up to the engine.

I've seen some cars that set P0089 and have no driveability issues, just the fault comes on, and others that have a shudder on hard acceleration, or other issues at cruise.

If yours doesn't return, or there are no driveability concerns, you may need to wait for something to fail completely to identify the problem since the pumps are so expensive.

There is also a separate control unit that just controls the pump, it's mounted under the car above the fuel tank - theoretically those go bad too and command the pump incorrectly, but I've never heard of someone actually replacing it.

It's almost always either the pressure sensor or the pump.

[Turbo00]

Drew, thanks very much for the info. FPR performance is what my code scanner translated it as too. Is the pressure sensor pn - 12787705? I'll go with that if the light comes back. Eeuro lists the pump assembly (pn 12763086) as "only" $330, so I guess it could be worse. If I learn anything useful in fixing this, I'll post it up here as it seems like a relatively common thing as the V6's get older.

Thanks again!
Chris

[BurnsSide42]

We've replaced a number or pumps for this code. Usually the first time it comes on it's a low fuel related issue - but if you keep getting it you will likely need a new fuel pump assembly. Does you car not have factory warranty remaining? This would be covered on an 08' or if it's CPO.

[Turbo00]

Burns, apparently the 4yr/50k ran out this past november (in-service date was 11/2007); dealer said this was not considered powertrain (5yr/100k). You can imagine my happiness.

[S&SAuto]

Code has come on once on my 07 combi Aero- half tank Slamming it on a on ramp...
Never got it again . this occurred 9-12 months ago..

Called Drew P Seconds after it happened Funny thing..

[Turbo00]

It went off yesterday morning, and she drove home from Boston without issue, still off today after driving into work. Fingers crossed, and from now on we're keeping it above 1/4 tank...