2008 Acadia Crank No Start

Michael Mobile Technician Clinton, Utah Posted   Latest  
Discussion
Driveability
2008 GMC Acadia 3.6L (LY7) 6-spd (6T75)
Crank / No Start

I volunteered to help some folks out that have fallen on hard times. They have a GMC Acadia that would not restart after stopping at the store 2 years ago. They need the vehicle to run so one of the spouses can go back to work. I stopped and bought a battery. When I got to the home I installed the battery and tried to start the vehicle. It is cranking and the scan tool displays about 150 RPM. No hint of starting. No codes are setting in PCM. There is a nice square wave to fire the coils. (4 wire module built in coil) Since the injectors are nicely buried, I was not able to access them to backprobe. I had left my laptop at home with SI access, so no idea which wires to probe at PCM. The fuel pump is coming on. I told the family that I would have to do some research and get back with them.

When back home I checked the wiring diagram for the injectors and it looks like the power is routed through a relay and then split to two 15A fuses. One fuse is for each bank. So the relay is a prime suspect. The tank is showing about 1/8 full. Maybe fuel is just too low. I looked for a fuel pressure testing port but could not locate it. Maybe on the back side of the engine?

When I go back over I plan on taking some starting fluid. I figure if it will start on starting fluid then chances are the problem is in fuel delivery and not mechanical. Once mechanical is at bay for a second, I plan on connecting a low Amps probe on relay circuit. In using my labscope, I can then look to see if there are peaks indicating the injectors are firing. If the injectors are firing then I can mostly rule out a computer problem. That likely leaves either low pressure due to no fuel or a bad pump. I guess I could add a couple of gallons of fuel earlier in the plan however the pump does not have the "dry" sound you get when the tank is empty. I am trying to keep my out of pocket expense as low as I can.

I am doing this in their driveway. Just wondering if anyone has any thoughts of tests I can do without removing components or jacking it up?

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Interesting
Brian Owner/Technician
Amanda, Ohio
Brian Default
 

I just posted on one that had water in the gas. And on that MY there should be a Pressure test port at the end of the fuel feed tube towards the rear of the engine. Cant remember what years, but i know 13MY you need a adapter. As you found the Ignition coils are super easy to test. The fuel injectors are a pain. I perform amperage measurements at the ECM due to the harness is wrapped tight and…

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Michael Mobile Technician
Clinton, Utah
Michael Default
 

Brian, Thanks for reminding me of your post. Since the tank is nearly empty, that is a real good possibility.

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Jeff Technician
Oklahoma City, Oklahoma
Jeff Default
 

What year is this acadia? 2009 and newer will be direct injected, the 2008 and older are port injected.

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Dan Owner/Technician
Ingleside, Texas
Dan Default
 

...Jeff it Says 2008 at the top of the post...I assUme he entered it correctly. ...Dan H. ...South Texas...

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Dan Owner/Technician
Ingleside, Texas
Dan Default
 

…Whatever you do DO NOT start it on what fuel is IN IT (the TWO YEAR OLD stuff)...Get it ALL out of there SOMEHOW...put in ALL NEW FRESH...and then figure out what is REALLY happening...even if it HAD started it prolly would have NOT been good for the valves /guides (IMHO)...it SHOULD hit on spray...but only be attempted once there is no longer that OLD FUEL...just some advice from an old…

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Michael Mobile Technician
Clinton, Utah
Michael Default
 

Hi Dan, That is good advice. Last thing I want is to get it running and hang the valves. That would be a bad day.

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Agree
Victor Owner/Technician
Doral, Florida
Victor Default
 

I would be more comfortable with a cranking speed of 200 or more.

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Agree
Dan Owner/Technician
Ingleside, Texas
Dan Default
   

...After two years of sitting a little of fine mist lube in the intake stream might be highly beneficial to those cranking RPMs...the cylinder walls could be slightly distressed after such a long vacation from the pistons reciprocating to TDC and back...Dan H.

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Michael Mobile Technician
Clinton, Utah
Michael Default
 

Victor, Thank you for the observation. It was 29 degrees Fahrenheit outside. That would account for the slow cranking.

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Justin Mobile Technician
Herriman, Utah
Justin Default
 

Current ramp the fuel pump. You can see the speed of the pump to determine if it’s out of gas. Too fast it is free spinning. I agree with Dan, replace all the fuel. Jump the fuel pump relay/drive module and test pump. Then find a line and pump the old fuel out. Take a sample to test for alcohol content at the same time.

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Thanks
David Diagnostician
Philadelphia, Pennsylvania
David Default
 

Based on the Mitchell schematic, if the coils have power supplied properly then the coils should also. If the computer is trying to fire coils then seems to me that timing is good enough for the computer to figure out engine position. Sounds like a fuel supply or quality problem to me. Would definitely start with a couple gallons of gas first especially if the starting fluid fires the…

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Dan Owner/Technician
Ingleside, Texas
Dan Default
 

...David and Justin...I was wondering if it was a GDI engine(didn't look)...there is a '12 Equinox (3.0) and a '15 GMC Acadia (3.6) in my immediate family...and BOTH are GDI...it wouldn't change my advice either way...but...that old fuel should be OUT of there before proceeding with an attempted fire up after a 2 year sit up like that (IMHO)...Dan H.

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David Diagnostician
Philadelphia, Pennsylvania
David Default
 

Not a GDI car, that was my first though as well. If it was then you would be able to look at low and high fuel pressures on the scan tool.

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Michael Mobile Technician
Clinton, Utah
Michael Default
 

Hi David, I was looking at the OE diagram for coil circuit. Now that I have gone to the injector diagram, I see they are fed by the same relay. I wish the OE diagram would have mentioned both. That definitely helps.

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Lorenzo Diagnostician
Collinsville, Oklahoma
Lorenzo Default
 

Before running a bunch more tests. Start with the basics. These Vans are bad about the connectors under fuse box coming lose or corroded. Usually the bolts are stripped that hold the connectors to the fuse box (engine compartment)

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Gary Owner/Technician
Buena Vista, Colorado
Gary Default
 

Mike, You're batting zero with 2 year-old gas. As other have said, get rid of the old gas because it won't start the engine. I always use a can of Seafoam with the new gas just to help clean the moisture and gum deposits out of the fuel tank. Just my personal experience with working on older vehicles...

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Michael Mobile Technician
Clinton, Utah
Michael Default
 

Thank you all for working on this with me. Today I took over fresh gasoline and put a few gallons in the tank. I then gave the vehicle a shot of Ether. It started but I immediately knew why they stopped driving it. It amazes me that they would not remember. When I asked for a history, it just quit running. They failed to remember the rod knock.

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Dan Owner/Technician
Ingleside, Texas
Dan Default
 

…Rut Ro (in my best Scubby Doo voice)...selective amnesia ??...could be a chunk of carbon (seriously) that broke loose and is banging around in there (I have SEEN and heard this personally...especially after a LONG sit...sounds just like a rod knock)...drive it like you stole it ... and it either blows UP ...or ...blows the carbon chunks OUT...what is there to loose at this point???...Try…

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Gail Technician
Garner, North Carolina
Gail Default
 

Since it's resolved let me tell you a story...I grew up at fathers used car lot/garage/bodyshop/salvage yard/bait & tackle shop...ummm...well most of that is true. My sister drove an I believe 75 Ford LTD. Blew up FOUR engines, which my dad provided engines and i installed FOR FREE. When 4th popped, due to over-heating, blow a hose, waterpump leak, whatever, we said ENOUGH. The temp/hot…

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Alejandro Technician
San Diego, California
Alejandro Default
 

Gail I coudnt agree with you more I work on a Fleet of Taxis, and most of drivers depend on the vehicle to get them around to do business even for their own personal use. The maintnance is provided to them as part of the leasing of the vehicle even though it comes at no extra cost they do the craziest things you can only imagine not bring their car in for a simple service let alone a major repair.

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Brian Owner/Technician
Amanda, Ohio
Brian Default
 

WOW, thats something you think they would remember. All in All at least some of use learned something from this post. I know i did. Thanks

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