no oil pressure

i recently bought the car its a 90. the head gasket was blown so of course i replace it but while i was at it i took off everything to give it a nice clean and i just started the car yesterday and it needs to be timed thats for sure but theres no oil pressure and a knock from the timing chain which is a result of no oil pressure. anyone know why i have no pressure?

um... did you put oil in it?, how do you know there's no oil pressure? did you prime the pump? How did you time it? I would get that set and then look for other things, might even be the problem.

there is oil in it. i primed the pump. i know theres only 5 lbs of oil pressure because i hooked up an oil preesure gauge. and as for timing.....welll i timed it. haha. everything was done according to the proceedures that AllData provides.

I Have Same Problem , I Changed Timming Chains , And When I Put All Back Oil Pressure Light Still On , Nissan Want $300 Bucks For A New Oil Pump ., So I Get One From Junk Yard ....no Oil Pressure Again , Some Times When I Press Gas Oil Pressure Ligth Goes Off , But Only Some Times. 2 Oil Pumps , 2 New Oil Pressure Sensors, 2 New Oil Filters ..... I Dont Understand Whats Wrong ... If Have Any Ideas Please Post.it Thanx

havnt really been working on the car lately but the past few days i have beem. i found out why there was no pressure in the system. turns out the O-ring that goes between the oil pickup line and the block was pintched so it wasnt sealing. i have oil pressure and the car is going to get timed tomorrow. should run like a champ.

good. i was gonna chime in with you probably have a restriction somewhere.