Strange problem when cold...

[jpaitala]

Lately I have been having this strange problem at mornings when the truck has been sitting still for over 8hr. It starts fine, but as I start to drive it nicely changes from 1st to second gear and then starts to jerk... After couple of minutes when it has warmed up this jerking no longer continues. But this is starting to worry me up.

Any ideas what to check and what to do to prevent any upcoming major repairs.

Thanks.

[markrinker]

What size tires?

[jpaitala]

265/65/16

[C.K. Piquup]

Sounds like cold fuel.Check to see if fuel heater is working(same unit as fuel filter housing).What is the temperature when this happens?The fuel heater element is the tube in the center.The wires come into the back of filter housing base.

[jpaitala]

It has been around 8-10C(45-50F) in the mornings now....

[C.K. Piquup]

I suspect the fuel heater,then.Plug in the block heater.What happens?At those temps,it should help.If so,I still think fuel heater.

[tom.mcinerney]

I dunno.

If search this forum may find post by member Damork; he installed a relay in the main power wire to transmission.
I ssume you've checked for DTC codes?
The APP may be involved.

May want try search/post at other forum, as
"GM Light-trucks ", or "2500HD/3500 HD Trucks & Drivetrain ".

Some additional links, possibly relevant(?):
http://www.hmmwv.org/HMMWV/pubs.htm
(ok, a hummer site!)
http://answers.netgearhead.net/ubbthreads.php
http://bbs.netgearhead.net/categories.php?Cat=
http://www.454ss.com/Articles_new/red/4L80E_Transmission_Problems.asp
autotransinc.com.
drivetrain.com

[jpaitala]

Damm.. I meant to say 265/75/16 tires previously, but wrote wrong...