my Hummer H3, 2007,
I suffer from sudden issue, the car is cranking but not starting. I wait 10 minutes, then I start up the engine and drive away.
this happens mostly some mornings, and rarely in mid of the day.

Also, while driving, I feel like riding a horse, the acceleration is up and done and the indicator on dashboard is going up and down, feeling the car racing and slowing, until I give more race, or reduce speed to stop that riding feeling.

mechanics said it is a crankshaft issue, must be changed. others, said petrol pump. and I don't know !!.. any advise pls.

 

Miles on the H3????

Google search GM Passlock.

When was the last time you cleaned the MAF and Throttle Body (TB)? Not related to difficulty starting, but is related to running rough and symptoms of slow reaction/over reaction TB. Acts like it wants to stall/rough idle -No CEL -What To Do:

 

BTW, you posted this same/very similar issue before back in 2016. What gives?

 

 

Hello there,
it is 207K.

most probably, the workshop did not clean it, since start driving it at 155k. even the previous owner might not clean them.