please help as I do not have a mechanic in my town with the knowledge to solve the issue with my canyon. This is a 2011 gmc canyon with 5.3L approx 160k miles. The symptoms are. Once the vehicle is at operating temperature and has reached highway speed then coming to slow the truck just boggs and is sluggish to an unsafe point. This has been going on for 9 months 4 trips to supposedly best mechanic in town. And 6 trips back to the dealership. Still not solved. I am now confident there is not a real mechanic in this town so I'm reaching out for help from you guys. Thanks in advance. I know this is a 10 year old truck but it is my baby. When this first started i thought it had a bad spark plug and or wires so i changed those. Then i thought the trans was stuck in high gear. Which is still my thought is the trans isn't shifting proper. All the mechanics have told me that wasn't it.... so The first mechanic put a new aftermarket fuel pump in and then later a fuel control module. The dealer said that new fuel pump was faulty so they put in a new oem fuel pump and reprogrammed the module. Later the dealer said the fuel vent line was broken. Then later the dealer said the fuel level sensor was bad why the new oem fuel pump didn't have a good sensor i dont know. I am over $5k into labor for two fuel pump install jobs as well everything else. I can't afford much more please help. Thanks

 

Welcome to the forum. You didn't mention anything about the check engine light. The dealer should have checked, but anyway is it on?

 

Is the check engine light on? This sounds like fuel related, what level of gas is in the tank? I'd suggest not running it below a quarter tank.

 

Thanks for asking as soon as I hit submit post I realized I forgot to mention that is doesn't have any codes. The fuel tank is about 5/8 full when it started sluggin today. Thanks again

 

the problem is sluggish on decell when warm...the problem only happens when warm on decel? got it.

 

That's pretty interesting, so what happens when you do this and it isn't up to temperature?

Also if you think it is the transmission have you tried to put it into tiptronic and manually down shifted to see if you can pin point exactly when it's happening?

I agree with the other members that it seems fuel related but it seems odd to replace a fuel pump when the car acts fine in every other situation and only when decelerating (When the car is not pumping as much fuel into the vehicle) That it would start to bog down? Seems like a sensor to me.

When it starts to bogg down and stutter does it feel like it's stalling? Does it recover? and if so how does it recover? When you start stepping on the gas or when you leave it alone?

Also when decelerating does this happen when applying the brake? or if you let it coast does it still happen?

I know these are a lot of questions and some aren't really related but i'm just trying to get into the seat of your car and join our brains together hahhaha

Keep us posted!

 

Thanks Canadian Tech for putting your thoughts into this. So last I picked it back up from the dealer who said they couldn't find anything. With there being no codes they are unable to diagnose. Due to Covid I am unable to take the mechanics for a ride to show them. They plan now is to make a video while driving. When I picked it up last night it took about a mile to start the issues. First when hard accelerating it stuck in 2nd or 3rd gear. It would redline and not up shift until the accelerator was released. Next after the trans is in the higher gear. And coming almost to a stop is when it bogs. Like it is stuck in high gear. The truck doesn't have tiptronic so I manually pulled the gear shifter to lower gears and that did not change the bog. I believe at this point I'm going to have to fix it myself so any advice on where to start would be greatly appreciated. I was thinking to start with a brake switch, throttle position sensor, and trans shift solenoids. ..
on side note i just purchased a 2017 chevy silverado that came from Canada and i could not believe the rust on under carriage. Do all vehicles in Canada rust underneath them extremely fast like that or did i buy something someone was parking in a Salt pond. Thanks so much

 

Shift soleniods does sound logical to me. I don't think they are difficult, nor expensive.

 

any car from the rust belt...great lake areas of Canada or USA will be rusted after 3 to 5 years.
post a video so we can hear the engine and see the tach.

 

yea from what you've just said solenoid is where i would definitely start. How did your dealer start changing the fuel pump when the transmission is stuck in a gear? I feel like people just dont care about their work anymore. I had to take my dog to numerous vets who all wanted to take his toe off until finally one took the time to diagnose it and let it heal and now it’s fine. I think all you have to do is care and think it’s not even about skill sometimes.

Solenoids usually go bad when your transmission fluid is overdue. How does your fluid look?

youll be changing it anyway i think because solenoids are under the pan?

and yea depending on how bad your definition of rust is we have lots. In the west like B.C. cars are super clean because no snow and clean roads. I’m in alberta but we dont use much salt. In the east like ontario its another story. Trucks break in half on hoists ive heard after being eaten alive by rust. Thats one of the reasons you find them at such a good rate. Good thing yours is still fairly new tho not sure if yours came from the east tho.