1998 GMC Sierra 1500 305 Vortec Slow Acceleration/No Power

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Joined: Fri Sep 20, 2013 10:50 pm

1998 GMC Sierra 1500 305 Vortec Slow Acceleration/No Power

Unread post by TEXGMC610 » Fri Sep 20, 2013 11:03 pm

I have a 98 gmc 305 vortec that is slow at acceleration and overall no power(less power than a 305 should have). I have rebuilt the complete top end minus the throttle body. I have replaced all sensors except mass airflow and O2 sensors. I also have not replaced the cat but it isn't clogged because it has been knocked out by previous owner. Could the cat being knocked screw with operation of the truck? I'm just at a complete loss, I don't know where to go other than replacing cat and mass airflow. I don't wanna do that unless I know for sure. Any help would be appreciated. Thanks!

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Joined: Sun Oct 14, 2012 11:52 am

Re: 1998 GMC Sierra 1500 305 Vortec Slow Acceleration/No Pow

Unread post by scotty » Fri Sep 27, 2013 10:37 pm

A catalytic converter that has been knocked out cannot cause your problem.
You either have a low fuel pressure problem, or a bad MAF.

Try starting the truck, disconnect the MAF, if it stalls- restart it, then take for a drive to see if the acceleration is any better. If it is, the MAF is bad.

Check fuel pressure with a gauge. It should be over 60 PSI when running.

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