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My 2010 GMC Acadia SLT started showing some issues recently. I need your advice to pin-point the culprit.
The problem started like while driving, it shows Reduced Engine Power with check engine light ON and the car barely moves (with very less power) and with a smell of gasoline inside the car (through the AC vents). When I scan the car it showed P0087 (Low Fuel Rail Pressure) and P0089 (Fuel Pressure Regulator) along with P0300 and P0302. The car was blowing white thick smoke.
I towed the car to a workshop and they suggested to replace the Fuel Rail Pressure Sensor and got my car back after 2 days as this happened at the weekend.
After 2-3 weeks the same exact problem happened and it showed the same error codes. This time workshop asked me to replace the High Pressure Fuel Pump. I got my car back after 2 days as that too was happened during the weekend.
After 2-3 weeks the same exact problem happened again with the same error codes and this time I just kept the car in the parking by thinking that the problem was getting solved by itself and might not be because of the replaced parts. The next day I checked the car - it shows the same problem. I didn't do anything - but just wait for another day. On the second day - I checked the car and it is working well.
After around 1 week the same problem - same codes. Kept the car for 3 days and it is back to normal again. When I scan it, I saw the long term fuel trim is showing –ve value (-7% for both banks). As I believe that there is some issue related to the fuel system – I did the following to understand what is going on.
1. I believe the fuel pressure should be something around 50PSI in 'Key ON engine OFF' condition (please correct me if I’m wrong). But, in my case, my scan tool showed around 7PSI. I'm not sure this can be checked using a scan tool rather than a manual manometer.
2. Also, as I understood from some YouTube videos, the rail pressure should remain almost stable regardless of the engine RPM. But, in my case - the Fuel Rail Pressure goes high from 650PSI to almost 1750PSI (at around 3000rpm).
3. After I run the car for almost 20 minutes and then when I stop the engine and keep the key in ON position - I saw the rail pressure increases from 650 to almost 1000PSI. The gauge pressure also increases significantly. I'm not sure if this is normal.
4. Short term fuel trim on both banks keep fluctuating and it is not stabilizing to 0 even after a new baseline in Long term fuel trim is set.
5. Long term fuel trim on both banks shows -ve value. It shows around -7%. I remember during the faulty time (the above-explained problem) LTFT was showing like -25% which indicates rich condition. I’m confused why the computer was saying LOW FUEL PRESSURE while it is a rich condition
6. I noticed that the value of LTFT on both banks increases with increase in RPM.

Previously, the issue was showing after I drive the car for a while (in closed fuel system) - but now, it started showing immediately after start too (in open fuel system).

I would like to give you some additional information which I'm not sure if it has a relation to the current problem.
1. This car was showing code P0420 (Catalyst System Low-Efficiency Bank 1 - Right Side) and P0430 (Catalyst System Low-Efficiency Bank 2 - Left Side) since more than 2 years and I have never tried to repair it.
2. A few months back this car stopped on the highway and towed to a workshop. They found that there is no fuel in the tank - but the gauge in the car was showing almost 40% fuel. Mechanic removed the fuel tank and checked the fuel float sensor which was attached to the fuel pump and they just kept it back. He said it could be due to some kind of stuck or something of the float sensor and then that problem never happened again. But, after that, a couple of times - I have noticed that the fuel gauge in the car just jumps (like for example from 70% to 30% or from 50% to 80% something like that).
Sorry for the long write-ups. Please see the attached image of scan data (RPM vs LTFT). I have attached some pdf files which are the freeze frame data in which you may see the fuel trims are 0. That is because this error occured after I clear my error codes.
 

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Couple of things, I am not a pro so take my input for what is worth (an enthusiast Acadia owner with some DIY experience). 0:)

According to the Repair Manual, your fuel pressure when the pump is commanded ON should be between 56 and 62 PSI. So your numbers seem out of whack.

Do you have an alternate way to test fuel pressure? Not sure I would trust those numbers if they are coming from your scanner.

Are the readings you quote above from the scanner or from an actual fuel pressure gauge attached to the fuel rail?

I don't see any problems with your fuel trims either. However, greater than 20% LFFT should have triggered a DTC. Did you get one and just cleared it? You may have multiple issues going on here. You should start diagnosing with a clean DTC slate if possible.

By the way, you should tell your shop to stop throwing parts at the problem and properly diagnose this issue.
 

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what about the fuel pressure regulator? Was that ever looked at and/or replaced?

BTW, pressure numbers of 56 to 62 are for my 2008. Your's may be a little different but probably not the high numbers you see.
 

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If you have ignored the P0420 and P0430 for two years, it is a good possibility all these things are related.
In fact the workshop advised me not to replace it due to couple of reasons. it is quite expensive here, as per them this issue will show-up again within few months for all US made cars here in UAE, this part will not affect any other parts ( these were their reasons). Now, I want to know if I really needs to replace those. Everyone who knows about it - please advise me on it.


Couple of things, I am not a pro so take my input for what is worth (an enthusiast Acadia owner with some DIY experience). 0:)
According to the Repair Manual, your fuel pressure when the pump is commanded ON should be between 56 and 62 PSI. So your numbers seem out of whack.
Do you have an alternate way to test fuel pressure? Not sure I would trust those numbers if they are coming from your scanner.
Are the readings you quote above from the scanner or from an actual fuel pressure gauge attached to the fuel rail?
I don't see any problems with your fuel trims either. However, greater than 20% LFFT should have triggered a DTC. Did you get one and just cleared it? You may have multiple issues going on here. You should start diagnosing with a clean DTC slate if possible.
By the way, you should tell your shop to stop throwing parts at the problem and properly diagnose this issue.

I want to know if the quoted fuel pressure is applicable for my vehicle. I was unable to find this information from the service manual (received from speleos).This vehicle is having a non-return fuel system. I don't know about your 2008 model is the same.
I double checked the pressure reading with a gauge and it showed the same as scan tool
If you check the freeze frame data, you can see the DTC was set with LTFT at 0% which means something else is triggering a DTC. I need a more detailed/complete factory service manual to understand this. Appreciate if anybody can provide with a complete service manual which explains step-by-step instructions to diagnose DTC codes.
I tried diagnosing with a clean DTC and that is what you can see 0% LTFT in freeze frame
Here in UAE, it is very hard to find a good workshop who diagnose the things properly (nearly none in my knowledge). They used to replace suspected parts one-by-one. If we approach GM dealer things are worst, they will ask us to replace a bunch of parts together whatever they suspect and it will cost a lot.


what about the fuel pressure regulator? Was that ever looked at and/or replaced?
BTW, pressure numbers of 56 to 62 are for my 2008. Your's may be a little different but probably not the high numbers you see.
I think - in returnless fuel system, there is no fuel pressure regulator or it is called high pressure fuel pump. My shop has replaced it already as mentioned.
 

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I bought a 2012 Acadia and I've had this problem 3 times and each time it has gone away on it's own. The first time was several years ago and I had the white smoke and smell of gasoline. My 18 year old son was driving and I thought he blew the motor. I also thought it was the high pressure fuel pump because of the codes and after getting a quote from the dealer for around $1100 to do the job I decided to look for parts and do it myself. Luckily it went away before I order the parts. Then it happened again a year later and then once this spring. Don't know what causes it or why it goes away. Good Luck and if you figure it out let us know because now I'm wondering why replacing the pump wasn't the answer.
 

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If you have ignored the P0420 and P0430 for two years, it is a good possibility all these things are related.
In fact the workshop advised me not to replace it due to couple of reasons. It is quite expensive here, as per them this issue will show-up again within few months for all US made cars here in UAE, this part will not affect any other parts ( these were their reasons). Now, I want to know if I really needs to replace those. Everyone who knows about it - please advise me on it.


Couple of things, I am not a pro so take my input for what is worth (an enthusiast Acadia owner with some DIY experience). 0:)
According to the Repair Manual, your fuel pressure when the pump is commanded ON should be between 56 and 62 PSI. So your numbers seem out of whack.
Do you have an alternate way to test fuel pressure? Not sure I would trust those numbers if they are coming from your scanner.
Are the readings you quote above from the scanner or from an actual fuel pressure gauge attached to the fuel rail?
I don't see any problems with your fuel trims either. However, greater than 20% LFFT should have triggered a DTC. Did you get one and just cleared it? You may have multiple issues going on here. You should start diagnosing with a clean DTC slate if possible.
By the way, you should tell your shop to stop throwing parts at the problem and properly diagnose this issue.

I want to know if the quoted fuel pressure is applicable for my vehicle. I was unable to find this information from the service manual (received from speleos).This vehicle is having a non-return fuel system. I don't know about your 2008 model is the same.

I double checked the pressure reading with a gauge and it showed the same as scan tool
If you check the freeze frame data, you can see the DTC was set with LTFT at 0% which means something else is triggering a DTC. I need a more detailed/complete factory service manual to understand this. Appreciate if anybody can provide with a complete service manual which explains step-by-step instructions to diagnose DTC codes.
I tried diagnosing with a clean DTC and that is what you can see 0% LTFT in freeze frame
Here in UAE, it is very hard to find a good workshop who diagnose the things properly (nearly none in my knowledge). They used to replace suspected parts one-by-one. If we approach GM dealer things are worst, they will ask us to replace a bunch of parts together whatever they suspect and it will cost a lot.


what about the fuel pressure regulator? Was that ever looked at and/or replaced?
BTW, pressure numbers of 56 to 62 are for my 2008. Your's may be a little different but probably not the high numbers you see.
I hope in returnless fuel system, there is no fuel pressure regulator or it is called high pressure fuel pump. My shop has replaced it already as mentioned.
 

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Discussion Starter #10
I bought a 2012 Acadia and I've had this problem 3 times and each time it has gone away on it's own. The first time was several years ago and I had the white smoke and smell of gasoline. My 18 year old son was driving and I thought he blew the motor. I also thought it was the high pressure fuel pump because of the codes and after getting a quote from the dealer for around $1100 to do the job I decided to look for parts and do it myself. Luckily it went away before I order the parts. Then it happened again a year later and then once this spring. Don't know what causes it or why it goes away. Good Luck and if you figure it out let us know because now I'm wondering why replacing the pump wasn't the answer.
Sure - I will update it here
 

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If you have ignored the P0420 and P0430 for two years, it is a good possibility all these things are related.
[FONT=&quot]In fact the workshop advised me not to replace it due to couple of reasons. It is quite expensive here, as per them this issue will show-up again within few months for all US made cars here in UAE, this part will not affect any other parts ( these were their reasons). Now, I want to know if I really needs to replace those. Everyone who knows about it - please advise me on it.[/FONT]
 

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Couple of things, I am not a pro so take my input for what is worth (an enthusiast Acadia owner with some DIY experience). 0:)

According to the Repair Manual, your fuel pressure when the pump is commanded ON should be between 56 and 62 PSI. So your numbers seem out of whack.

Do you have an alternate way to test fuel pressure? Not sure I would trust those numbers if they are coming from your scanner.

Are the readings you quote above from the scanner or from an actual fuel pressure gauge attached to the fuel rail?

I don't see any problems with your fuel trims either. However, greater than 20% LFFT should have triggered a DTC. Did you get one and just cleared it? You may have multiple issues going on here. You should start diagnosing with a clean DTC slate if possible.

By the way, you should tell your shop to stop throwing parts at the problem and properly diagnose this issue.
[FONT=&quot]I want to know if the quoted fuel pressure is applicable for my vehicle. I was unable to find this information from the service manual (received from speleos).This vehicle is having a non-return fuel system. I don't know about your 2008 model is the same. [/FONT]
[FONT=&quot]I double checked the pressure reading with a gauge and it showed the same as scan tool[/FONT]
[FONT=&quot]If you check the freeze frame data, you can see the DTC was set with LTFT at 0% which means something else is triggering a DTC. I need a more detailed/complete factory service manual to understand this. Appreciate if anybody can provide with a complete service manual which explains step-by-step instructions to diagnose DTC codes.[/FONT]
[FONT=&quot]I tried diagnosing with a clean DTC and that is what you can see 0% LTFT in freeze frame[/FONT]
[FONT=&quot]Here in UAE, it is very hard to find a good workshop who diagnose the things properly (nearly none in my knowledge). They used to replace suspected parts one-by-one. If we approach GM dealer things are worst, they will ask us to replace a bunch of parts together (whatever they suspect) and it will cost a lot.[/FONT]
 

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what about the fuel pressure regulator? Was that ever looked at and/or replaced?
BTW, pressure numbers of 56 to 62 are for my 2008. Your's may be a little different but probably not the high numbers you see.
[FONT=&quot]I think in returnless fuel system, there is no fuel pressure regulator or it is called high pressure fuel pump. My shop has replaced it already as mentioned.[/FONT]
 

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[FONT=&quot]I want to know if the quoted fuel pressure is applicable for my vehicle. I was unable to find this information from the service manual (received from speleos).This vehicle is having a non-return fuel system. I don't know about your 2008 model is the same. [/FONT]
Numbers I quoted for fuel pressure are for a 2008 model. The information below (in another post) is in the Fuel System Diagnosis Section for the 2010 Model North America Variant. Read it and see if you can find something of value. I am not sure about the fuel system differences across model years it but again I am not an expert. So take this with a grain of salt. It may apply or may not apply to you. :grin:

I need a more detailed/complete factory service manual to understand this. Appreciate if anybody can provide with a complete service manual which explains step-by-step instructions to diagnose DTC codes.[/FONT]
There is no such thing to my understanding. Some repairs have step for step but for diagnosing specific DTC's there is no direction on what do do.

You will find scattered information online. But for complete factory manuals you have multiple choices (not free). Printed Factory manuals can be had on ebay for ~ 300 bucks. Also online subscription services also provide most information and it's searchable. These are used by most independent shops. Best bet is to get it directly from GM's as I think they are all sourced from the same place. It is now available to individuals. I have seen the content from these different options they all seem to share the same info.

Let me know if you need the link to GM's Official Options or others. You may be locked online due to regional rights, etc. You will need to try to find out.

Here in UAE, it is very hard to find a good workshop who diagnose the things properly (nearly none in my knowledge). They used to replace suspected parts one-by-one. If we approach GM dealer things are worst, they will ask us to replace a bunch of parts together (whatever they suspect) and it will cost a lot.[/FONT]
Then you are on your own, it will take time but I am sure you can fix your issue with the right tools and information.
 

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Fuel System Diagnosis

Circuit/System Description
The engine control module (ECM) supplies voltage to the fuel pump control module when the ECM detects that the ignition is ON. The voltage from the ECM to the fuel pump control module remains active for 2 s, unless the engine is in Crank or Run. While this voltage is being received, the fuel pump control module closes the ground switch of the fuel pump and also supplies a varying voltage to the fuel tank pump module in order to maintain the desired fuel line pressure.

The fuel system is an electronic returnless on-demand design. A returnless fuel system reduces the internal temperature of the fuel tank by not returning hot fuel from the engine to the fuel tank. Reducing the internal temperature of the fuel tank results in lower evaporative emissions.

The fuel tank stores the fuel supply. An electric turbine style fuel pump attaches to the fuel tank module inside the fuel tank. The fuel pump supplies fuel through the fuel feed pipe to the high pressure fuel pump. The fuel pump also supplies fuel to a venturi pump located on the bottom of the fuel tank module. The function of the venturi pump is to fill the fuel tank module reservoir. The fuel tank module contains a reverse flow check valve. The check valve maintains fuel pressure in the fuel feed pipe in order to prevent long cranking times.

Diagnostic Aids
Observe the Misfire Counters or perform the Fuel Injector Balance Test to help identify a leaking fuel injector.

Circuit/System Verification
NOTE
Note

Repair all fuel system related DTCs before performing this diagnostic.

Inspect the fuel system for damage or external leaks before proceeding.

Verify that adequate fuel is in the fuel tank before proceeding.

The fuel pump may need to be commanded ON a few times in order to obtain the highest possible fuel pressure.

Before proceeding with this test, review the User Manual CH 48027-5 for Safety Information and Instructions.

Ignition OFF, all accessories OFF, install a CH 48027 Gauge or a CH 48027-100 Gauge .

NOTE
Note

DO NOT perform the Fuel System Diagnosis if the engine coolant temperature is above 60°C (150°F). High fuel pressure readings may result due to hot soak fuel boiling. With the engine OFF, the fuel pressure may increase beyond the pressure relief regulator valve's setting point of 690 kPa (100 psi) ± 5 percent.

Ignition ON, engine OFF, command the fuel pump ON with a scan tool. Verify the fuel pressure is between 345–690 kPa (50–100 psi) with the fuel pump running.

Engine idling at normal operating temperature, the Fuel Pump Flow Control Module Fuel Pressure Sensor parameter should read between 300–400 kPa (43–58 psi).

Circuit/System Testing
NOTE
Note

The fuel pump may need to be commanded ON a few times in order to obtain the highest possible fuel pressure.

DO NOT start the engine.

Ignition ON, engine OFF, command the fuel pump ON with a scan tool and observe the fuel pressure gauge while the fuel pump is operating. Verify the fuel pressure is between 345–690 kPa (50–100 psi).

If the fuel pressure is greater than the specified range, replace the fuel tank module.

If the fuel pressure is less than the specified range, test, inspect, and repair the items listed below. If all items test normal, replace the fuel tank module.

Restricted fuel feed pipe

Inspect the harness connectors and the ground circuits of the fuel pump for poor connections.

Verify that the fuel pressure, after the fuel pump is turned off, decreases to 500–599 kPa (72–87 psi), and does not decrease more than 34 kPa (5 psi) in 1 minute from that point.

If the fuel pressure stays above 600 kPa (87 psi), replace the fuel pump module.

If the fuel pressure decreases more than the specified value, perform the following procedure:

Ignition OFF, relieve the fuel pressure. Refer to Fuel Pressure Relief (CH-48027) | Fuel Pressure Relief (Without CH-48027) | Fuel Pressure Relief (High Side).

Disconnect the chassis fuel feed hose from the engine compartment fuel pipe.

Install the J 37287 Shut-Off Adapter between the chassis fuel hose and the engine compartment fuel pipe.

Open the valve on the J 37287 Shut-Off Adapter .

Ignition ON, command the fuel pump ON with a scan tool and bleed the air from the CH 48027 Gauge or the CH 48027-100 Gauge .

Command the fuel pump ON and then OFF with a scan tool.

Close the valve on the J 37287 Shut-Off Adapter .

Monitor the fuel pressure for 1 min.

If the fuel pressure decreases more than 34 kPa (5 psi) within the specified time, locate and replace the leaking fuel injector(s).

If the fuel pressure does not decrease more than 34 kPa (5 psi) within the specified time, replace the fuel tank module.

Relieve the fuel pressure to 69 kPa (10 psi). Verify that the fuel pressure does not decrease greater than 14 kPa (2 psi) in 5 min.

If the fuel pressure decreases greater than the specified value, replace the fuel tank module.

Operate the vehicle within the conditions of the customer's concern while monitoring the fuel pressure with the CH 48027 Gauge or the CH 48027-100 Gauge . The fuel pressure should not drop off during acceleration, cruise, or hard cornering.

If the fuel pressure drops off, test, inspect, and repair the items listed below. If all items test normal, replace the fuel tank module.

Restricted fuel feed pipe

Inspect the harness connectors and the ground circuits of the fuel pump for poor connections.

If the fuel system tests normal, refer to Symptoms - Engine Controls , Fuel Injector Solenoid Coil Test , and Fuel Injector Balance Test.

Happy Reading!!!:wink:
 

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Hi. can you tell me Please where is Fuel Pressure Regulator 1 and Fuel Pressure sensor on 2010 GMC Acadia cause there are 1 at on top passenger side under intake manifold and other i see a 2 wire going to a driver side connected to a looks like a sensor and is connected to a fuel filter or sum-thing like small canister that is bolted to the fuel line. After reading on line some mechanic said there are no fuel pressure regulators on 2010 Acadia. hear is my code readings: P0090, p0122, p0223 and lest code is p0193. I have used autel ht200 and run live data and it looks like the problem is related to fuel pressure (reading some number are in RED. Hear is pictures:
8788
8789
8790
8791
 

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also what voltage should go to the sensor on top under upper manifold with 3 wires and sensor that is at front left attached to a fuel canister with 2 wires. The OHMs Resistant of the sensors too Please. Thanks.
 
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