2000 Yukon XL 5.3 labored starting

[JC-sr5]

Hello

 

Recently the truck has been starting poorly. It has never failed to start, but chugs very slowly almost like the battery is dead. I thought maybe the one in it was going since it was several years old, bought a new one and put it in, made sure battery going in was fully charged, but still having the same issue. It doesn't run poorly, volt gauge reads normal, but just starts like battery is low. Sometimes it chugs more slowly than other times. It does have 253k on the original starter, alternator is recent and is an AC-Delco part, so I do not think it could be causing this. I have not crawled under it to take a look at the starter yet. Problem has existed for about 2 weeks now. Any help is appreciated. 

 

Thank you.

[txab]

Check starter and condition of cables and wiring

[rjgti]

use a scan tool to measure crank voltage or do it by hand with a dvm at starter

[Colossus]

Did you get a brand new alternator or is it a rebuilt?  if it is a rebuilt, return it and upgrade to a brand new.  May not be the issue but it WILL be an issue eventually.  Never buy a rebuilt alternator or anything..

 

Common problems with the GMT-800s-

- Battery cables corroded (where you can't see them) (always replace the cables with new cables, never buy the crimp/screw on terminal heads, ALWAYS get new complete cables)
- Fuel Pump/Fuel sending unit/Fuel module in the gas tank (ALWAYS replace the entire module, which will include the fuel level sensor)

- 4x4 electronic switch in the dash

- Transfer Case pump rub leak (both on the HDs and regular duty)
- Slip Yoke clunk- (replace with a nickle plated slip yoke)

- Piston Slap- Running a good full synthetic oil along with premium oil filter will lessen this significantly, I always used Mobil-1 or Valvoline full synthetic 5w30 with great results. 

 

What am I missing, folks?

 

 

[JC-sr5]

The alternator is a rebuilt Ac Delco Unit, I've never had any issues with them in the past  

 

Changed the starter today, was not as much of a hassle as I had expected it to be, and now it starts perfectly and quickly every time. I also ordered a new starter relay since is was only about $6 and isn't difficult to change, might as well the one on it is original. Hopefully this has solved the problem, time will tell it if was some type of voltage issue and it goes back to crap starting.

 

My 4x4 switches are original and still work, but do have the piston slap, have always used conventional, and the fuel gauge goes wacky when you get below 1/3 of a tank, not worth dropping the tank I don't feel at this point, unless gauge goes completely, it needs to make it to 300k I think it can do it