Just bought. 5.9 cummins Can`t get it to start without pushing gas pedal slightly. Runs good after warms up. Still have to give it fuel to start.

no car told maker or model or engine size.
there are lots causes that, hard starts
if spark good and strong and even HV spark wire sets fresh.
the short list.

1. bad fuel
2. too much fuel cranked and floods
3. IAC bad, idle air valve stuck and wants to flood cold.
4. cold idle is the big clue, where too low. IAC failing
5. EGR sticking open at idle. possible.
6. if you press gas Pedal, at 5% (about) and starts easy and likes that until it worms up that means the IAC is dead.
7. I stop here lots more, no car told.

all cars modern EFI is it EFI> have IAC and ISC valves 1 or both.
and if stuck idle fails. hot or cold.
no car told why post like that 100 year of cars and 10,000 engines.
????

Assuming the engine is in good shape and not in need of a major tune-up, check your carburetor choke. It's not closing when cold. Clean and adjust.

Get a service manual and follow the instructions. Far too complicated to cover here.

Also, make sure you know how to properly SET the choke on a cold start. Slowly push the gas pedal to the floor and let up. Start engine without touching gas. If it's REALLY cold, like 0 degrees, you can hold the pedal halfway down while starting, after setting the choke.

If the fuel pressure is normal, it could be a sticking idle air control valve.

try replacing your PVC valve or EGR valve also check for vaccumm leaks

Have you checked the fuel pressure regulator for leaks into the intake

I had the same problem but I did two fixes for it (1) when I bought the truck several years ago the duel tank switch was pushed in but i never fixed it and just would switch tanks with the switch pushed into the dash. after awhile it acted like it didn't know what tank to draw from point is i finally replaced the switch and it ran, but still ran rough, (2) on the left side of the motor their is an EGR valve (it was green colored vacum hose) I replaced that vacum hose and now it runs great.

HAVE THE CATALYTIC CONVERTER CHECKED FOR BEING PLUGGED.

Definately overfueling. Don't apply any gas pedal when starting. lightly tap and crank. If still does it, fuel pressure regulator malfunction- good luck It should fire up without give it fuel. not like the good ole cars.

START WITH CHANGING FUEL FILTER FIRST , NEXT THE FUEL PUMP IS POSSIBLE TOO.

016 Engine Misfire Misfire Scan Data Find someone who knows what scan data is an knows how to use it .Intake manifold vacuum leak .
Rough Running When Cold GMC Yukon