1999 GMC Savana

gmc
2500

#1

When starting out either cold or hot, almost zero power, backfires a few times, than taks off like a shot. Runs OK until I shut er down, than the same problem everytime. I did the injector juice, no help, some suggested a plugged converter, tested, no problem. All I know is that it is a 6 cyl, throttlebody injection. It’s almost like a few of the cyclinders are being “flooded”. Had this to three machanics, no idea.


#2

You could have a leaking head gasket. Coolant will leak into a cylinder while the vehicle is not running, as little a few drops, and cause it to run rough until the coolant is burnt off. This kind of leak will not produce white exhaust. Is the check engine light on?


#3

No check engine lite… have not looked at the exhaust. Sounds like it might be it, I’ll get it checked and thanks…

Jim


#4

Actually yes you should look at the exhaust. While it is running poorly see if it is blue or black. Blue would mean oil could be leaking into a cylinder or cylinders while the vehicle is not running. Black would suggest that a fuel injector is leaking fuel into one or more of the cylinders. If you see nothing from the exhaust I’d pursue my first suggestion.


#5

The low profile distributor cap, and rotor are known to cause misfire problems. Especially the cheap aftermarket ones that cause carbon dust inside the distributor cap, that clogs the vent screen which can hold moisture inside the cap. Have you checked the cap, rotor, and screen?


#6

I don’t go for TBI in 1999,too late, more like CPI or even multi-port.