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

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

clandr1

Full Access Member
Joined
Apr 20, 2012
Posts
910
Reaction score
999
Location
Dallas/Fort Worth, Texas
For sure. It's not exhibiting signs of failure other than a bit of low pressure KOEO and having a hard time starting on first crank randomly. Figured other than effort, wasn't a big deal to fire the parts cannon at it since the OEM is at 165k. If it doesn't fix my problem, hopefully I'll get another 165k out of this Delphi. Still runs like a turpentine cat, so might not be the cure.

I think you are having the same issue I did a few years back. My truck started having an occasional hard start condition where I had to crank it 2-3 times, and then it would still be very hesitant to start "strong". After some diagnosing with a fuel pressure gauge, I found that the pressure would quickly bleed off with key on, engine off, after the pump finished priming. I paid the dealer $1,100 to install a new fuel pump, but it came with a lifetime warranty if it ever failed again so I figured it was worth it. I believe that was around 160k miles (approx 7 years ago), but I'd have to check my records to be sure.

Turns out, the fuel pressure regulator was failing and allowing pressure to bleed back down to the fuel tank after the pump stopped priming. Sucks that, for my year model at least, the FPR is build into the fuel pump assembly. If I owned an earlier year model GMT800 (believe 2000-2003), the FPR would've been right on the fuel rail and easy/cheap to replace.

Either way, I hope the new fuel pump fixed it right up! It solved my problem, and I suppose it will solve yours as well.
 

mattbta

Full Access Member
Joined
Jun 19, 2012
Posts
1,052
Reaction score
1,892
Location
Frisco, TX
I think you are having the same issue I did a few years back. My truck started having an occasional hard start condition where I had to crank it 2-3 times, and then it would still be very hesitant to start "strong". After some diagnosing with a fuel pressure gauge, I found that the pressure would quickly bleed off with key on, engine off, after the pump finished priming. I paid the dealer $1,100 to install a new fuel pump, but it came with a lifetime warranty if it ever failed again so I figured it was worth it. I believe that was around 160k miles (approx 7 years ago), but I'd have to check my records to be sure.

Turns out, the fuel pressure regulator was failing and allowing pressure to bleed back down to the fuel tank after the pump stopped priming. Sucks that, for my year model at least, the FPR is build into the fuel pump assembly. If I owned an earlier year model GMT800 (believe 2000-2003), the FPR would've been right on the fuel rail and easy/cheap to replace.

Either way, I hope the new fuel pump fixed it right up! It solved my problem, and I suppose it will solve yours as well.
Mine is a flex fuel 2004 and I replaced the regulator several weeks ago as it was on the rail. So maybe that in combination with the pump will fix it? Here's hoping. Thanks!

Sure sounds similar. I've noticed I can play with letting it prime a few seconds and then it will fire. Sometimes no prime needed. Others, it will extended crank and sort of light up a cylinder at a time. Usually when the first attempt fails, it starts strongly on the second.
 

Rocket Man

Mark
Supporting Member
Joined
Dec 25, 2014
Posts
25,966
Reaction score
50,662
Location
Oregon
I think you are having the same issue I did a few years back. My truck started having an occasional hard start condition where I had to crank it 2-3 times, and then it would still be very hesitant to start "strong". After some diagnosing with a fuel pressure gauge, I found that the pressure would quickly bleed off with key on, engine off, after the pump finished priming. I paid the dealer $1,100 to install a new fuel pump, but it came with a lifetime warranty if it ever failed again so I figured it was worth it. I believe that was around 160k miles (approx 7 years ago), but I'd have to check my records to be sure.

Turns out, the fuel pressure regulator was failing and allowing pressure to bleed back down to the fuel tank after the pump stopped priming. Sucks that, for my year model at least, the FPR is build into the fuel pump assembly. If I owned an earlier year model GMT800 (believe 2000-2003), the FPR would've been right on the fuel rail and easy/cheap to replace.

Either way, I hope the new fuel pump fixed it right up! It solved my problem, and I suppose it will solve yours as well.
On my 02 the FPR went out and I was able to find a rebuild kit for it on Amazon. It contained new o-rings etc. Cost me about $8 and a half hour to remove it, rebuild it and reinstall it. Now it’s buried in the tank and by the time you drop the tank, might as well replace the whole assembly. Can’t keep it simple can they?
 

Walchit

Full Access Member
Joined
Aug 29, 2021
Posts
447
Reaction score
911
Built a hillbilly hot tank for this crankshaft. It's windy AF, so I raised the Smokey Joe up closer. If I get the gap at the top right I should be able to load it with coal and regulate the temp with the bottom damper. Its only at 115° right now though.
 

Attachments

  • 20220406_160714.jpg
    20220406_160714.jpg
    220.7 KB · Views: 6
  • 20220406_160531.jpg
    20220406_160531.jpg
    199.9 KB · Views: 6
  • 20220406_163838.jpg
    20220406_163838.jpg
    228 KB · Views: 5

Walchit

Full Access Member
Joined
Aug 29, 2021
Posts
447
Reaction score
911
Dang wind is killing me. Got this baffle pretty clean though. Took it to the diesel/psc100 tank afterwards to stop the flash rust. This crankshaft gets heavy trying to scrub it. Thinking about tossing it in a trash bag and going to the car wash
 

Attachments

  • 20220406_200103_HDR.jpg
    20220406_200103_HDR.jpg
    140.9 KB · Views: 5

Walchit

Full Access Member
Joined
Aug 29, 2021
Posts
447
Reaction score
911
I can live with this.
Forgot about the oil pan though, so I just put it in. Hopefully it doesn't take all night.

Oh, and these are the updated valve covers right? I picked them up for 50, came with a set of 862 heads, rocker arms and 15 pushrods lol.
 

Attachments

  • 20220406_232218.jpg
    20220406_232218.jpg
    225.2 KB · Views: 5
  • 20220406_232256.jpg
    20220406_232256.jpg
    158.8 KB · Views: 5

Tonyrodz

Resident Resident
Joined
Feb 16, 2012
Posts
30,993
Reaction score
45,170
Location
Central Jersey
I can live with this.
Forgot about the oil pan though, so I just put it in. Hopefully it doesn't take all night.

Oh, and these are the updated valve covers right? I picked them up for 50, came with a set of 862 heads, rocker arms and 15 pushrods lol.
Hopefully they're not Castech 862 heads. I think one on my van is cracked. Got a pic of the logo on them? Castech logo looks like a battery.
 

George B

¯\_(ツ)_/¯
Joined
Feb 5, 2020
Posts
7,637
Reaction score
18,095
Location
Oconomowoc, Wisconsin 53066
Personally, I would pull the rear cover and see what kind of goodies await you inside. At a minimum, it’s the cost of diff fluid and a cover gasket. If it’s not that, at least you’ll have fresh gear oil back there.

Make sure you can get the fill plug out first. I know how that Jersey rust is.
I am with these guys. My guess is that the side or spider gears are damaged. The good thing is, I don’t see G80 on the RPO which means that parts are not too expensive if the ring, pinion and bearings are ok. Time to pull the cover.
 

Forum statistics

Threads
129,251
Posts
1,812,847
Members
92,354
Latest member
Off Road Pedia
Top