2007 GMC Yukon Hard Start/Battery level fluctuation

[BacknBlack]

Hey Guys,
New to the site and I was looking for some input on a couple of issues that came up on a recent trip.
I had been having the "long cranking before engine starts" problem for the last month or so. I figured it was the check valve in the fuel pump getting bad. To combat this, I would turn the key partially forward and let the pump purge the fuel line back up with gasoline to the motor before I would turn the key all of the way forward to start it. In 80 degree weather in NW Iowa, this was working. I took a trip to Tulsa last week and it was 100 degrees plus for the 4 days we were there. No matter what I tried, the engine would crank over quite a while before the car would start. Sometimes the starter would kick out and I would have to turn it over again to get it to fire. Now that we are back in 80 degree weather, it is still doing the same thing it did in Tulsa last week.
My thougt is that the fuel pump was/is getting weak, and the excess temps and pressure it endured while in Tulsa has taxed the pump enought where it is need of replacement. Thoughts? Am I on the right path, has someone had this issue? Is it solely the check valve in the pump? I put on 1200 miles during the trip, and it ran absolutely fine once it was started and running. It ran well, even with the temps in rush hour traffic down there.

Anotehr issue I had was the stabilitrak warning. This occured while driving down the road at highway speeds. I think this alarm is due to the voltage levels fluctuating. When I got the alarm, the battery gauge was reading less than 14 volts. I would guess it was closer to 12 volts. After more driving, the guage bounced straight back up to 14 volts and the alarm cleared. Before the trip, I replaced the battery with a new AC Delco battery. I have not checked for loose wiring yet, but was going to tonight. I was also wondering if anyone had this problem and if the altenator ended up being the culprit?

This is a 2007 Yukon XL with 74k miles. This engine was rebuilt under warranty by a GM Dealer for the oil consumption which these 5.3 liter engines are notorious for.

Thanks in advance for any feedback!

Travis

 

[erald01]

I am fairly new to these rigs too, but from reading a few threds seems like the volatge flactuation could be due to some elctrical issue or weak/faulty alternator. I am assuming the long crankings were due to low voltage, the starter not haveing enough power to turn over the engine. if this was a weak fuel pump you would hear a wining noise from the pump also if its going bad it would have gone by now completly, but you said it drove fine for 1200 miles. I say check the alternator first make sure its not one of those faulty one that do not charge the battery properly.

 

[Peaches]

Mine is in the shop right now for this. Be very careful driving it. I started out with weird quirks, moving on to having stabilitrack and traction control flash, following by losing all electric on the highway. It will get progressively worse. Your battery and alternator will probably test out bad, but it's most likely wiring or computer issues.

Have fun. I'm having a blast with this shit.

Please see this thread for more detailed and varied experiences, including my own.

http://www.tahoeyukonforum.com/foru...age=3&highlight=stabilitrack+flash+electrical

 

[BacknBlack]

Thanks erald01.
The motor and starter sound fine when they are turning over, plenty of battery power there. I just think the fuel pump is having a hard time getting the fuel back up the rail to the engine since the check valve has failed and lets the fuel drain back into the tank.
I had a fuel pump go out on a 97 HD Chevy with a 454. Before it totally gave up, there was some whining noise coming from it indicating it was going to fail.
While I do not think the actual fuel pump is bad on my 2007 Yukon, I do believe the check valve in the fuel pump assemble is bad, which would require the entire assemble to be replaced.
There is no whining coming from the fuel pump on my 2007 Yukon.
I am thinking I need to replace the pump and the altenator. Possibly not the altenator, if I find a loose wire/connection as other posters have commented about in the forum.
Thoughts?

Thanks,
Travis

 

[Peaches]

I also want to add, before my truck went nuts on the highway, it was having a hard time kicking over. Not all the time, but some of the time. I too, thought it was my fuel pump. However, I have had a bad fuel pump before and I couldn't hear it on this one. You can normally hear it going out.

 

[BacknBlack]

i am having fun with this shit too!

Mine is in the shop right now for this. Be very careful driving it. I started out with weird quirks, moving on to having stabilitrack and traction control flash, following by losing all electric on the highway. It will get progressively worse. Your battery and alternator will probably test out bad, but it's most likely wiring or computer issues.

Have fun. I'm having a blast with this shit.

Please see this thread for more detailed and varied experiences, including my own.

http://www.tahoeyukonforum.com/foru...age=3&highlight=stabilitrack+flash+electrical

---------- Post added at 02:23 PM ---------- Previous post was at 02:12 PM ----------

Here is the reason I changed my battery:
Before our trip, I went out to my garage and programmed in destinations to the Navigation. While I was doing this, I had the key turned forward and the navigation was the only thing I had on with the door opened. I was doing this for about 10 minutes. All of the sudden, I got the stabilitrak warning on the dash and battery system alarm. I went ahead and tried to start the Yukon and the battery was dead.
I was kind of excited that the low battery happened at the same time the stabilitrak alarm came in. I thought this is why I was getting the alarm in the past, because of the low/fluctuating voltage. The battery I replaced was the original battery, so I was hoping a new battery would remedy the stabilitrak alarm. As you can tell in the post before, it did not. That is why I am now leaning towards a loose wire or faulty altenator.

Thanks,
Travis

 

[Peaches]

Has it done it while driving? Mine started doing that, and graduated after a few months to total electrical failure while driving. It also has a nasty habit (pre and post new battery) of completely dying as soon as you park and pull the key. It will stay dead anywhere from a few seconds to 20 minutes (or all day, until some magic touch prompts it to spark to life).

It's a wiring problem or a computer. I'm still waiting on the dealer to call me back. The tech pulled 12 codes when he ran the scan.

 

[BacknBlack]

Bellis,
Mine has never completely died like yours has.
It gets the stabilitrak alarm and turns off the traction control. When it was happening earlier this year, it would happen when I was decelerating. I would come off the freeway to a stop light when it would occur. Once stopped and I started to roll again, there would be a hard bang on the transfer case from 1st to 2nd gear. I think that was the transfer case getting confused by the low voltage.
I had told my dealership months ago about the problem, but they of course have no answer.
The same goes for the hard starting issues, they have no answer there either.
That is why I have taken to this forum to see what people are getting for real results. I am not going to allow my GM shop to guess what could be going on, ie the throttle bodies which people have had replaced to no avail.

 

[Peaches]

Right, which is my problem. I still haven't heard back from them yet, but I'm sure their response will be something like "Oh, we went ahead and cleaned your terminals (for a million dollars) and that seems to have cleared it up." or "Turns out it was a bad throttle body" You know the rest.

So yeah, I don't have much faith, but I'm crossing my fingers. I can ignore the stabilitrack warnings, but when it totally loses power, I draw the line.

 

[BacknBlack]

Did you get any news back from teh dealership Bellis?