Running Rough - AIR Pump Removal? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

bluec10 · 05-31-2012, 03:41 PM

My '69 with a 250 L6 is running rough. I rebuilt the carb this spring and very carefully set it to factory specs. I did the timing and idle settings carfully as well. I still get hesitation on accelleration. New plugs, plug cables, points, condenser, rotor, and cap. I know vacuuum leaks could be the problem, so I disconnected the brake booster to see if it was at fault. Can't really tell a difference. Other seals seem to be OK.

The truck came with an original AIR pump, which, outlaw that I am, I removed. I plugged the manifold ports with brass screw-in plugs and put the alternator where the AIR pump used to be.

Would removing the AIR pump make a difference in how the truck runs? I'm just throwing it out there because I'm not sure where to go next.

chevytruckluver · 05-31-2012, 04:40 PM

Taking the AIR pump off will not cause a hesitation. The AIR pump was added to help tailpipe emmissions back in the day. It was just injecting air into the exhaust system to mix with what was just burnt or not burnt by the engine. It was a joke. It was just masking what the engine was really doing.

05-31-2012, 03:41 PM	#1
bluec10 Registered User Join Date: Apr 2002 Location: Manitoba, Canada Posts: 663	Running Rough - AIR Pump Removal? My '69 with a 250 L6 is running rough. I rebuilt the carb this spring and very carefully set it to factory specs. I did the timing and idle settings carfully as well. I still get hesitation on accelleration. New plugs, plug cables, points, condenser, rotor, and cap. I know vacuuum leaks could be the problem, so I disconnected the brake booster to see if it was at fault. Can't really tell a difference. Other seals seem to be OK. The truck came with an original AIR pump, which, outlaw that I am, I removed. I plugged the manifold ports with brass screw-in plugs and put the alternator where the AIR pump used to be. Would removing the AIR pump make a difference in how the truck runs? I'm just throwing it out there because I'm not sure where to go next. __________________ Present: 2015 Tacoma. Yeah, not a GM, but I love it. 1969 GMC 32,000 - fix, drive, relax, fix... 2019 BMW R1250 GSA - Yahoooooooo 1979 Honda GL 1000 - retro touring at its best. Past: '05 Sierra 4x4 - Had 270,000 KM and running well when it was written-off by a stop sign runner. '94 F-150 from the "F word" company. I'll admit it...good truck. Sold what was left of it for $800 to a guy who came to pick it up at 11:00 PM with cash in hand. Hmm. '79 Sierra Grande (Black) organ donor - perfect rebuildable 4-bolt 350 and a good TH350. '76 Sierra Grande (Orange) - hate isn't too strong a word. Kid who bought it turned it into a hot rod. '68 C-10 R.I.P. - Dad's old truck...too far gone to resurrect. '59 C-50 - with hoist. Truck is gone, wife isn't. Nuff said.

05-31-2012, 04:40 PM	#2
chevytruckluver Eat, Sleep, Drive a Chevy Join Date: Apr 2010 Location: the town of the cow, Texas Posts: 1,152	Re: Running Rough - AIR Pump Removal? Taking the AIR pump off will not cause a hesitation. The AIR pump was added to help tailpipe emmissions back in the day. It was just injecting air into the exhaust system to mix with what was just burnt or not burnt by the engine. It was a joke. It was just masking what the engine was really doing. __________________ Trey Silence may be Golden, but Duct Tape is Silver! 72 Short Step 57 "big window" short step



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