Wont stay started on 2001 Volvo S80

i put a new head gasket and a new timing belt on a 2001 volvo s80 2.9l. It will start but itll only run for a few seconds amd it will die. Im afraid to keep trying to start it. What should i do and how can i get it to stay running?

Asked by for the 2001 Volvo S80
Did you use all the cam and crank lock and aligner tools?

yes and i have double checked everything. I even took the head back off and redid all of it and double checked it again. And itl start for a few seconds and die still. Witch by the way the tools for this thing were very expensive. The motor only has 88000 mile on it.
Yep, the tools are expensive, but absolute necessary for the proper alignment and installation.
Can you retrieve any diagnostic code from the ECM?
Check if the throttle cable is not pinched to the starter bracket and the connector is seated properly, also check the grounds for proper connection. Actually I'd recheck all the electrical connections.
Do you have a way to check the fuel pressure?

I dont have a way to check the fuel pressure but i can take it to someone that can. Thank you for your support and ill keep you posted if i cant get it running. One more thing tho, i read it on the internet somewere that the key should be removed from the ignition. Well if this is true, i didnt pull the key out. What kind of problems would that cause if that were true? And if it could cause problems, will it be costly to fix cause i have alot of money wrapped up in this car.
Did you disconnected the battery before the repair?
Anyway, try this:
Disconnect both of the battery cables and connect them together for few minutes. It's easy to do with a jumper cable, make sure the cables are away from the terminals and can't accidently touch them. After about 5 minutes reconnect the cables. Turn the ignition ON, but don't attempt to start it yet. Push the accelerator pedal down to the floor and let it back and now try to start it.

i got it running. I hooked the battery cables together for a few mins and did what u said. The car ran for about 15 seconds and died. Then it wouldnt start back up at all. I pulled the dip stick for the oil and it smelled like gas. I unhooked the mass air flo and it ran perfect. I hooked it back up while it was running and it cut out but did not die. After about 5 mins of running itll cut out but will not die. I turn the car off and tryed to start it and wouldnt start again untill i unhook the mass air flo. What could this mean? But there is gas in the oil tho.
Can you get any diagnostic trouble code out of it? Does the throttle assy. makes a sound (self test) when you turn the key on? Does it have a white or yellow label on the throttle assembly?

its yellow. I took the car to someone so they could help figur this thing out. The codes are reading cam sensor and something about advanced timing. When i warms up u can start it with the mass air flo hooked up but it will not start cold with it hooked up. Got any ideas?
ok there are no codes. It still will not start with mass air flo hooked up. But it will run when u hook it back up after u start it. When you try to drive it you have to push the gas almost to the floor before it will go. Ther isnt any motor noises when you drive it. The gas in oil stopped so no gas in oil now. Have any ideas on what possible could be the problem now? Thank you for helping me get it this far tho. All the other sugestions were very helpful. Thank you
I'd try to find someone with OE VIDA or DICE diagnostic computer and run a full system check on it among an ETM test. Regular scanners are not reliable on Volvos.