GMC Acadia Forum banner
1 - 8 of 8 Posts

·
Registered
Joined
·
3 Posts
Discussion Starter · #1 · (Edited by Moderator)
New to the forums, struggling with a solution for the wife's car (owned since new). A few months back it would randomly go to "reduced power", but recovered with a key cycle and didn't set any codes (this got the throttle body replaced). Finally it "stuck" in reduced power and set a code. The initial codes were P0091 Fuel Pressure Regulator 1 Control Circuit Low and P0087 Fuel Rail/System Pressure - Too Low Bank 1. Research suggested the in tank pump was the likely culprit, so I changed that, followed by the fuel pump control module. Then the high pressure fuel pump, the ECU/PCM and finally the fuel rail pressure sensor. Each part was replaced and the car faulted before the next part was installed. Each part was replaced in order of "the most likely" cause based on the trouble codes.

Over time the fault code has morphed from simply P0091 (low) to include included P0627 (open) and today the ONLY code that remains is the P0627.

I have checked the wiring to and from the various fuel components I have replaced and find nothing loose and don't see any bad connectors or obviously broken wires. I am out of ideas and wonder if anyone else has had a similar problem and managed to solve it. Perhaps a mystery ground strap???

Below is a graph of the data I have most recently collected. This was prior to changing the pressure sensor (yesterdays task). You can see that things look good for a while - actually on a cold start it takes 10-20 minutes to get the "reduced power". Everything seems in line then the HP pump dials to "off" (no idea how that is done) and the fuel tank pump goes to max. With only ~100 psi to the direct injectors you are in "reduced power".

You can re-set the the reduced power by disconnecting the battery, but if hot it comes back nearly immediately. If cold (overnight) it seems to be good on crank and the fault re-occurs in 10-20 minutes.

The idea that it was heat related is what drove me to reluctantly change the ECU (I have experienced similar issues with headlights on an older car that had bad grounding straps - where should I look?). There are no fuel pump relays that I find, so assume that function is built into ECU.

Any help appreciated.

H

Rectangle Slope Plot Parallel Font
 

·
Super Moderator
Joined
·
22,459 Posts
If you don't have a service manual, you'll find links to several in another forum section. Diagrams in the 2010 or 2014 manuals may help you locate grounds for the Acadia's fuel pump circuit. Little with the fuel pump circuits has changed through run of the Lambda platform since the switch to GDI engines in 2009.

Try establishing an alternative ground to the fuel pump circuit. That should help to determine if there's either a ground, or power supply problem. Good luck!
 

·
Registered
Joined
·
3 Posts
Discussion Starter · #3 ·
Offering an update - still no solution.

Since posting this, I thought I had it licked twice, only to be disappointed. Changed the fuel rail pressure sensor - no change. Decided to pursue the grounding route and located and cleaned every ground connection I was aware of. Actually took a buffing wheel to the spots, buffed the paint off and reinstalled the ground straps. In that activity I found that one of the harnesses behind the fuse box was not fully seated. Fixed that and added a wire tire to ensure future security (connector tab is broken). That seemed to fix it - got to town and back no problem, was ready to take it to the lake.

Before committing to the lake trip, I decided to run the Acadia up the the local Buccee's (~ 20 miles) with the boat on the bumper. Was most of the way there, when I had to make a hard stop and the fault re-appeared. I had my blue driver plugged in and was monitoring on the phone. As I was creeping down the road in limp mode with the boat attached, I decided I had nothing to loose by attempting to reset the "check engine" light / circuit while driving. Was surprised when it reset and a lift of the throttle and re-application had full power restored. Got fuel for the boat (ethanol free fuel) started the trip back and again had to make a hard brake for a stop light and it faulted. This time I reset while sitting at the light and managed a smooth strip - no unplanned stops - home for the last 19 miles.

Now I am back to looking for a loose wire or connection. Something that might move with hard breaking.
 

·
Registered
Joined
·
2,291 Posts
Perhaps a connector to the fuel pump under the vehicle? Corrosion may be an issue inside a connector? I think you may be right. . .. some sort of intermittent electrical connection .
 

·
Super Moderator
Joined
·
22,459 Posts
Check condition of the connector beneath the vehicle to the left of the fuel tank. That has been a trouble spot for other problems.
 

·
Registered
Joined
·
3,372 Posts
Check condition of the connector beneath the vehicle to the left of the fuel tank. That has been a trouble spot for other problems.
I was thinking the same thing. There was once a pic on this site showing how that plug could get stretched. As I recall GM had a fix where the wires for that plug would be extended.
 

·
Super Moderator
Joined
·
22,459 Posts
.. There was once a pic on this site showing how that plug could get stretched. ...
If it can't be found here, there will probably be one on the Traverse forum. Rbarrios has posted the pic multiple times on both forums.
 

·
Registered
Joined
·
3 Posts
Discussion Starter · #8 ·
If it can't be found here, there will probably be one on the Traverse forum. Rbarrios has posted the pic multiple times on both forums.
Thanks guys,

I am familiar with the connector, I had to disconnect it when I dropped the fuel tank to change fuel pump. Kind of under the B pillar area on the driver side? I don't see anything wrong with it, and I have gone back too it and checked that it was seated, even pealed back the wire loom (split plastic POC) to inspect, because I saw a damaged spot in the loom. All was good inside, still..... I could get a new (to me) connector at the junk yard and splice it in. I'll give that another look.

We get lots of rain in Houston, but at least we don't get salt on the roads. Underside of the car only has the slightest corrosion.

On the grounding diagram, I have confirmed all but one. I see there is a ground wire up by the radiator support that seems to come from the ECU harness. I have to pull the entire front facia to access it, so that will be a weekend job.

Cheers and thanks for the input. Will let you know when I finally figure it out.
 
1 - 8 of 8 Posts
Top