Ground from hell.

nickb2

Wrench. Diagnostic Tech.
Joined
Nov 22, 2008
Messages
8,641
Likes
139
Points
63
Location
St-Hyacinthe, Quebec, Canada
#1
Make
gmc
Model
savana g3500 crew 12k lbs +
Year
2008
Miles
146k
Engine
6.0l
Hi guy's,

As usual, I like to keep regular updates of my mistakes so others can learn what happens in a day in and day out job like us techs here. And also for alot of those very skilled "so called" non professionals. I know some very knowledgeable guy's here it is insane.

Anyways, the meat of the problem was this very heavy savana came to the shop stalling. Especially at lights. I get it in my bay. First I notice, check engine light.

Whip out the scanner, check trims, check live data first even before I check codes. Everything is fine, but I need to check codes, freeze frames, modes six data and I/M readiness monitors. Those are vital to a good scan and you record them for future use in the diagnosis. .

Anyways, codes come back B2 S2 shorting and lean performance and heater etc. It's working fine, wiring is fine, no reason to suspect. I know by way client is talking, it's losing gas.

I say maybe fuel pump. Lets go for a test drive. Back this heavy truck out, put it in forward, no go. Stalls. Need ten guy's to push it back in. :eek:

Mind you I gunned it. Now remember guy's, I fix about on average 1000+ cars and truck a year. So I gun pretty much any thing I touch. It has to be in and out cuz clients just keep coming. Probably a good sign for the shop and my future! REER's should be nice.

Anyways, back to the ground from hell.


I find a bad ground at frame near filler neck. It is nasty looking, I unbolt it, the rust is so so, I clean the ground up, still have resistance on pump neg circuit. I give that circuit my own ground to chassis, thus eliminating the OEM grounds elsewhere for this pump. I then check power, good to go, new fuel pump.

My reasoning, the high resistance and old age killed it. It is after all the OEM pump in there.

After many hours of fighting the straps and lines. Not being able to siphon any of the gas cuz the gas cart is crashed and nobody thought to tell management. I end up just pulling it down full but yet very well strapped to the trans jack and balance this thing to a reasonable level to work with. Find out they have to prime it with oil first to get the cart going. Really? Time for a new pump then in the cart and let me focus on this savana pump.

Siphon gas out with a hose and air gun into the cart whilst waiting for new cart pump. Fit back in new pump. But first, I had to modify the new pump for his gas generator/heater. Touchy, but it got done. Very small metal tubing to curve and kink o rings on, and not to mention drilling the new 617$ unit knowing this voids the warranty before even being plugged in.

Button it up, start truck, runs "A" ok. Check trims, not running lean, temps on engine are great for a drive cycle, all is good for a test drive. Back it out, put in drive, gun it, it stalls. F@@##$$% n shyte. 10 guy's to push it back in. :eek::mad:

More to come tomorrow with maybe pictures if I didn't throw out the heaping pile of rust gathering on my floor.
 
Joined
Nov 14, 2006
Messages
4,796
Likes
49
Points
48
Age
118
#2
Hey nick:

A 6L - remember when diesels were simple...?
Anyway following your story,
1) What would happen if you backed it out shifted to Drive then walked into the throttle like you owned it instead of the teenage WOT?
2) when it stalls - any new or Pending codes register?


PS ; What is Trudeau problem Donald asked him to sign a new NAFTA?