Author Topic: P0089 with no other DTC's - Replaced fuel pressure sensor to no avail (Read 25234 times)

2kwk4u · « **on:** March 03, 2012, 11:35:38 AM »

Edit: re-named this thread for future use in keyword searches.

Can someone please open their hood, turn the ignition to "run" without starting, and see if their fuel pump ticks rapidly? Trying to determine if it's normal for that solenoid to be active when the engine ISN'T running. I'm having a fuel pressure issue - dealer "could not duplicate," of course. So now I'm stuck trying to determine if it's the pump, pressure sensor or ECM.

Thanks in advance

snaponbob · « **Reply #1 on:** March 03, 2012, 11:55:44 AM »

Yup, really clatters for a while. Don't have to pop the hood. Been there - heard that.

So .... what is the problem you are having?

2kwk4u · « **Reply #2 on:** March 03, 2012, 12:24:12 PM »

BLUF: - DTC P0089 - fuel pressure regulator performance
- Monitored fuel pressure on DashDAQ is "sticking" high and climbing when it shouldn't be
- DTC P0087/P0088 are NOT setting (these are fuel pressure low/high, respectively - and the parameters for setting them are LESS variance than P0089)
- After I shut the engine off, but leave the ignition on, the fuel pressure on the DashDAQ continues to slowly climb (which seems to me physically impossible)

A year ago (seems like almost to the day) the fuel pump was replaced under warranty. That time I had P0087, P0089 obviously low fuel pressure on the DD, and limp home. They replaced the pump (and associated pipe section) but not the fuel rail or pressure sensor. This time around, things are different.

I always have boost and fuel pressure displayed on my DashDAQ, and the gauges pretty much mimic each other under normal conditions. Since the P0089 set, the fuel pressure will frequently shoot up under load/boost - but instead of coming back down quickly when I get out of the throttle it "hangs" at high pressure or even continues to climb upwards of 3,000 PSI.

Took it to the nearest dealership that services Pontiac. The same Buick dealer that replaced the pump under warranty last year. They did a half-assed diagnosis and determined nothing's wrong. At least they were kind enough not to charge me for it. But they suggested that if it sets another SES I should take it to a dealer that has experience with LNF and has technicians that have been to some specialized training for direct injection engines... When I got home and parked the car in my driveway, I noticed that the indicated fuel pressure keeps climbing even with the engine off. I then noticed that the solenoid on the pump was still running, but it still didn't make any sense to me that the pressure could climb from 500 PSI to 1500 PSI over the course of a few minutes without anything actually pumping fuel. (that solenoid just determines how much of each stroke from the pump actually gets pumped into the rail, vice dumped back into the pump itself)

Since you've helped me determine that it's normal for the HPFP solenoid to cycle even with the engine off, I think I'm going to just order a new fuel pressure sending unit from Rock Auto. It's only 30 bucks. It's not worth the hassle of taking it to another dealership that has a clue if all I need is a 30-dollar part.

TomatoSoup · « **Reply #3 on:** March 03, 2012, 03:00:30 PM »

Hmm. Well different experience here than Bob's. I just went out to my car, turned it on (no engine start) and no clicking sound. I added the fuel rail pressure on my Ultragauge and the reading was hovering around 68-69 PSI.

I briefly started the engine and the pressure jumped to ~2000 PSI. Turned it off again and the pressure did a slow descent.

Hope that helps.

Gentleman Jack · « **Reply #4 on:** March 03, 2012, 03:38:46 PM »

Two different results? Now I have to go test mine ......(running to garage....)

Ok, tripped and fell on the way to the garage. 2KWK4U- you owe me.

Results: same as TS. Silence.

Bob- your car may have something wrong with it too.

2kwk4u · « **Reply #5 on:** March 03, 2012, 07:18:32 PM »

Thanks, all for checking. I'm going to check mine again now that it's cooled off all day.

The clicking is pretty quiet - nearly inaudible. If I didn't live in a quiet neighborhood, I wouldn't be able to hear it a foot away from the pump.

2kwk4u · « **Reply #6 on:** March 04, 2012, 01:05:55 PM »

Update: The clicking is there cold or hot. So I ran another test today immediately upon parking in the driveway after running errands. I disconnected the solenoid to get rid of the clicking and see if that was somehow contributing the the fuel pressure ACTUALLY rising (this set a P0090 code - but that's easily cleared). Indicated fuel pressure still crept up after turning the engine off, turning the ignition to "run" and disconnecting the solenoid. I'm pretty sure my problem is a skewed fuel pressure sensor.

I'll update this thread with results when I replace the sensor.

2kwk4u · « **Reply #7 on:** March 07, 2012, 09:24:11 PM »

Will do. Might get to it tomorrow or this weekend. The P0089 hasn't popped back up yet. Got the sending unit in the mail today, but at this point it doesn't seem "critical" that I replace it.

On a hopefully unrelated note, I've noticed that I can hear the HPFP clatter get intermittently louder sometimes now. I think it may just be that I'm paying more attention though.

2kwk4u · « **Reply #8 on:** March 10, 2012, 11:38:15 AM »

Replaced the sensor this morning. No change in the readout behavior - the indicated fuel pressure still creeps up after turning the engine off following a drive. Maybe that's "normal" and has to do with heat soak or some sort of electronic circuit anomaly. P0089 still hasn't re-surfaced, so I still have no idea what caused it. Stabs in the dark here, but it may be any one of the following:
- Fuel pump getting ready to crap out
- ECM getting ready to crap out
- intermittent short somewhere
- bad tank of gas
I've decided not to waste any more time/money on it until the problem resurfaces. At that point, it'll probably go back to a different dealership that knows LNF better.

In the meantime, here's some pictures/words for BSS on the fuel pressure sensor replacement:

First things first, you'll need a 1-1/16" or 27mm deep well socket and the new sensor, of course

You'll want to take some measures so you don't spew gas all over the place. First, pull the fuel pump relay, then try to start the car. It shouldn't start, but this will get most of the fuel out of the rail. This WILL set a DTC that you'll need to clear

To ensure that the pressure in the rail is relieved, pull the cap off the schrader valve on the low pressure side of the HPFP

Put a clean rag over it and depress the valve (as if you're letting air out of a tire). A little gas will come out, but it shouldn't be more than a few drops

The sensor is on the front end of the fuel rail. You can see it here through the olive drab-colored fuel rail protector bootie (yes, that's a technical term)

Disconnect the wire, and remove the sensor

The old sensor removed

In hindsight, I should have cleaned off the debris BEFORE removing the sensor. Any of this crud that gets into the fuel rail is sure to find its way to an injector and cause problems...

New sensor

Old sensor - same Bosch part number

Even though the original didn't seem to have it, I ran a strip of Teflon tape around the threads of the new one to ensure a good seal. It has somewhat fine threads and isn't torqued all that tight into the fuel rail - DEFINITELY don't want to over-torque it and pull the threads out of the rail. That puppy is expensive!

Re-install the new sensor. Plug it in. Put the cap back on the schrader valve. Re-install the fuel pump relay. Clear that DTC. You're done

Arabas · « **Reply #9 on:** March 10, 2012, 11:50:35 AM »

great DIY post 2kwk4u!
hope you never get the code again

elff · « **Reply #10 on:** March 10, 2012, 12:34:10 PM »

Nice writeup
That will help someone down the road

Treeman · « **Reply #11 on:** March 10, 2012, 03:36:15 PM »

Thanks for the write up. If you do need to take it to a good dealer, Fox Chevrolet in Laurel knows their stuff. Ask for Mike Lewis when you call.

1LILNDN · « **Reply #12 on:** March 10, 2012, 08:28:02 PM »

I think that guy has been there quite awhile Now . Critterman and Chuck-doc found him a few years ago

2kwk4u · « **Reply #13 on:** March 10, 2012, 09:17:11 PM »

Yep, he has. Thanks for the tip, Treeman. Last time I went and saw him for the growling A/C compressor issue, they weren't much help. If the code re-surfaces, though, I'll take it to Fox and ask them to re-attack both issues.

Critterman · « **Reply #14 on:** March 11, 2012, 12:19:48 PM »

Mike is the service guy, I don't know who their Solstice mech is any more. Used to be the husband of the woman you got your keys from, but can't remember his name. i haven't been there since the day I meet treeman there. he was picking up his car and Mike introduced us.

elff · « **Reply #15 on:** March 12, 2012, 10:14:01 AM »

ewwwwwwwwwwwww hard copies

shabby · « **Reply #16 on:** March 12, 2012, 11:18:51 AM »

I noticed the fuel pressure rising on my car too when its off, it takes around 15 minutes to reach 2800psi and then it starts falling. But when you start the car at the pressure it'll throw the p0088 cel.

TomatoSoup · « **Reply #17 on:** May 20, 2012, 08:55:36 AM »

Scott... did you find a resolution to this? If so, what? My car just threw this code last night (after a bout of, ahem, heavy-footedness).

2kwk4u · « **Reply #18 on:** May 20, 2012, 12:13:58 PM »

Hey Mark... the code never has popped back up. I've since stopped paying attention to see if the fuel pressure behavior is the same as far asrising after shut down, but have no reason to believe it has changed. Car is still running as normal with no abnormal fuel pressure spikes or dips. Was yours only P0089, or did you get a P0087 or P0088 along with?

TomatoSoup · « **Reply #19 on:** May 20, 2012, 01:08:25 PM »

No, just a P0089. I haven't cleared it yet. I'll drive it some more and see what happens - see if it clears itself, or if not, I'll clear it and see if it comes back.

Thanks for the response. Hope your tour away is uneventful!

DeepBlueGXP · « **Reply #20 on:** May 20, 2012, 08:55:32 PM »

how much was the sensor?

2kwk4u · « **Reply #21 on:** May 20, 2012, 09:14:27 PM »

Quote from: DeepBlueGXP on May 20, 2012, 08:55:32 PM

how much was the sensor?

Quote from: 2KWK4U

Since you've helped me determine that it's normal for the HPFP solenoid to cycle even with the engine off, I think I'm going to just order a new fuel pressure sending unit from Rock Auto. It's only 30 bucks. It's not worth the hassle of taking it to another dealership that has a clue if all I need is a 30-dollar part.

DeepBlueGXP · « **Reply #22 on:** May 21, 2012, 11:05:08 AM »

thx, missed that one.

2kwk4u · « **Reply #23 on:** July 31, 2014, 10:45:19 AM »

Sorry to dig up an old thread. Still no resolution, but...

Same thing happened again today. Seems like my HPFP was pretty loud when I left the house this morning, but quieted down by the time I got to the end of my street (300 yards, *maybe*). I drove it about 40 minutes to where I needed to go and parked. When I came back out, I noticed the CEL. Pulled the code with my DashDAQ and it was P0089 (only). I didn't even remember this thread until I did a keyword search for "P0089." Drive home was uneventful, though I did baby it all the way home thinking my HPFP would puke its guts out if I nailed it...

Mark, did you ever get to the bottom of things with yours?

TomatoSoup · « **Reply #24 on:** August 02, 2014, 09:44:56 AM »

I'd forgotten about this issue too! Mine never came back.

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Author Topic: P0089 with no other DTC's - Replaced fuel pressure sensor to no avail (Read 25234 times)