What did you do to your NBS GMT800 Tahoe/Yukon Today?

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Sam Harris

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Finally got around to replacing the fuel pump gasket that has been leaking and caused the evap drive cycle failure. After shotgunning parts (purge valve, vent valve, canister) we got serious about troubleshooting it and it came to this. We used a smoke machine for a coarse diag, and a little air pressure after narrowing it down.

We (my son Nate and I) replaced the fuel pump about two years ago, using an AC Delco Pro/Gold pump, which included the gasket for the Flex Fuel pump. We're not sure if we messed up the gasket when installing, or if it was received that way. And we're not sure why it didn't fail evap back then; it's been good until about two months ago. I don't recall that we had to install the gasket on the pump that time, I think it was already on it. Anyway, now to get some gas to get it up to half a tank and run the evap drive cycle.

The gasket seems to have rolled a bit, or was malformed. You can see in the pic where it was leaking, all along the part with the light residue. The red triangle points to the start of the defective part, and it goes to the right several inches:

View attachment 347793

Here's a comparison of the old (upper pic) and the new (lower) gaskets. The new one (also AC Delco) is a less pliable material and looks like it will hold form better.

View attachment 347794

There is a strainer that slips into the tank filler stub, maybe to prevent siphoning? It just slips in and out but is the exact size for the inlet.

View attachment 347802

And, lastly, the pump and new lock ring as installed. To remove the old ring and install the new one we used channel lock pliers to put pressure between the ears on the tank and the notches in the ring. We did this on opposing ears with two pliers and so no hammer or punch needed.

View attachment 347803

So, on to a few test drives over the next week or so. Glad we were able to confirm the cause of the leak with the physical evidence.
Excellent work and write up! I’m glad you’ve got that taken care of, and your post will certainly benefit others!
 

Sam Harris

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I have never understood the point of the "tapacrap". Most of my phones for the last 5+ years have browsed forums beautifully. What's the idea behind that junk??
I'm feeling brave like I want to do some mechanical work this weekend!!
We will see what happens in the morning. I'm getting the itch to install my 2020 brakes but the current setup doesn't sqeak or anything!?!

Also that dude with the Bose delete thread didn't help. I used to be a serious audiophile and he got me thinking $$$$.
Yeah, I know those that haven’t used Tapatalk don’t have the same perspective to compare to a web browser. My phone works just fine, the difference is how the app organizes all your updates to very quickly and easily see, and respond to them. It’s honestly much, much faster than loading a page in a browser and scrolling around to read / respond, etc… to each his own though, it certainly is not without it’s faults.
 

02Z71Raven

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Since the old girl is just high enough for me to crawl under, I usually don't lift it to to do work under there. Problem is I couldn't get the leverage to break the bolts on the trans mount bar (don't know what that's called). Since I had some 5ah DeWalt batteries, I figured I'd try their impacts since I get em cheap. All I got to say is, you can break any bolt loose with these guys. I ripped those dudes out with a quickness. Now I can finish getting this Borla exhaust installed without buying air tools.
 

Rocket Man

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Since the old girl is just high enough for me to crawl under, I usually don't lift it to to do work under there. Problem is I couldn't get the leverage to break the bolts on the trans mount bar (don't know what that's called). Since I had some 5ah DeWalt batteries, I figured I'd try their impacts since I get em cheap. All I got to say is, you can break any bolt loose with these guys. I ripped those dudes out with a quickness. Now I can finish getting this Borla exhaust installed without buying air tools.
DeWalt makes great cordless tools, it was our shop’s choice. They actually decided to buy all Bosch to replace them with when they started wearing out but that stuff isn’t near what DeWalt is. They ended up going back.
 

02Z71Raven

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DeWalt makes great cordless tools, it was our shop’s choice. They actually decided to buy all Bosch to replace them with when they started wearing out but that stuff isn’t near what DeWalt is. They ended up going back.
I'm just using the 1/4”, but my brother uses the 1/2" at work and that things just crazy. I think the 1/4" is plenty enough but I'm planning on putting the 1/2” in the truck for road trips and off road for changing tires.
 

TollKeeper

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Installed a new Dorman 949-099 Air Compressor, and installed some used rear Z95 Magnaride shocks to replace my Z55 Air-Shocks. They came off a front wrecked 2013 Escalade with 42k miles.

To my surprise, the system works perfectly! No oddities in the tech2 voltages, or readings.

Remembering that my rear air bags were blown, and I think the drivers side rear shock was also blown.
The ride is completely different.

The entire job took about 90 mins.
 

Rocket Man

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Installed a new Dorman 949-099 Air Compressor, and installed some used rear Z95 Magnaride shocks to replace my Z55 Air-Shocks. They came off a front wrecked 2013 Escalade with 42k miles.

To my surprise, the system works perfectly! No oddities in the tech2 voltages, or readings.

Remembering that my rear air bags were blown, and I think the drivers side rear shock was also blown.
The ride is completely different.

The entire job took about 90 mins.
A ride on blown rear air bags is terrible that’s for sure. Glad it’s all working good.
 

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