I'm getting ready to sell my 1986 K5 Blazer and today I put the air pump belt back on the truck. I had been driving around for probably a year or so with out it. Next week I'll try and put the cat coverter back in. But since I put the belt on, now it seems under powered and under heavy acceleration it'll pop alittle bit when I let off the gas. Is this because I don't have the cat in there and there isn't enough back pressure to keep everything happy? I want to sell the truck with a smog certificate so I don't get low balled on price, so fixing this crap is kind of important to me. Thanks!!!

Bump!

I'm amazed the air pump is not frozen after not having a belt on it for a while.They don't like it. This could be causing it to lie down on accel.
As far as your decel pop the diverter valve is more likely junk parts and the check valves as well.
Good luck trying to get it to pass smog,cats seem to not work very well if they have been removed for sometime and then re-installed.I good thing you have going is '86 is the first year of TBI
'85 and down the E4MC carbs had a lot of problems passing smog.Plus since you are the seller you are responsible it passes smog.

Quoted: I'm amazed the air pump is not frozen after not having a belt on it for a while.They don't like it. This could be causing it to lie down on accel. As far as your decel pop the diverter valve is more likely junk parts and the check valves as well. Good luck trying to get it to pass smog,cats seem to not work very well if they have been removed for sometime and then re-installed.I good thing you have going is '86 is the first year of TBI '85 and down the E4MC carbs had a lot of problems passing smog.Plus since you are the seller you are responsible it passes smog.

Well it's a brand new cat, the old one took a shit.  It's an '86 but its still carbondated I wish it had EFI.