Intake Gasket?

[ottoman]

Well I figured out one problem with my truck. The intake gaskets are leaking. Would that cause bad fuel milage? It never set off any cel or nothing. So one problem fixed and a few more to go.

[8.1HD/ALLISON]

Leaking intake gaskets directly affect the calculated fuel mixture, so it could affect fuel milage.

[ottoman]

Ok thanks. Just checkin. Last time I drove it any distance at all. I filled up b4 I left town drove 120 miles and had a 1/4 tank of fuel left. I have know there was a problem but it was intermitent. And could never pin point it when it did act up. So I hope replacing the intake gaskets fixes this problem! Thanks again

[kylechovance99]

so i filled up my 99 silverado 5.3 litre motor lifted 6.5 inches on 35 inch tires and i usually get 600km to a tank well i only got 200, so i filled up again and used half a tank of fuel in 50 km why? what I've read so far it sounds like its probably an internal leak, so would that be the intake manifold or… and advice would be appreciated!