Rough start

[Capt Clay]

I have a Cummins 4BTA3.9 on start up it runs very rough for about 10 seconds and then quiets down, as if fuel is not getting to all cylinders,
can anyone diagnose this problem?

[Mistress]

I have a Cummins 4BTA3.9 on start up it runs very rough for about 10 seconds and then quiets down, as if fuel is not getting to all cylinders,
can anyone diagnose this problem?

Sounds like you may be getting air in the fuel system while at rest. Return lines weaping will do this.

Also can be anwhere from the tank pick-up to the lift pump, but that doesn't generally go away.

[Capt Clay]

Thanks for the reply mistress. I will check for air leaks. I have no fuel leaks, seems if air was going in, fuel would come out. Unless like you say it could be return at top of tank, I will double check, thanks again.
I have recently installed a single throttle control, could it be the linkage is not adjusted right and the fuel valve open just a little?

[Mistress]

Doesn't sound right to me. They'll run like crap if air is getting into the fuel input side. Too much air and they can not start at all and the system must be bled. The fact that it clears in ~10 seconds would point me in that direction.

By all means...check your linkage anyways.