engine shake at idle and low rpm

[davrac1]

hello,I was wondering if anyone knows what might cause a shake at idle and low rpm's.it runs great after that,no smoke,plenty of power.I just bought the suburban and I changed the fuel filter and that didn't help.it's a 96 suburban with #9 resistor,ssdiesel cooling upgrade,duramax fan, heatsink relocated to top of manifold.any help or suggestions would be greatly appreciated.

[TedReminder]

Look real close at the belt pulley on the crankshaft. The rubber part breaks and would cause the issue you describe. If you find the pulley bad, go one step farther and pull the main balancer for inspection and to check the key. The key is cheap, replace for peace of mind.
Ted

[davrac1]

thanks ted for the info I'll check it and see.

[grancito]

If that fails look for a bad injector.