Hesitation/lack of power

nwebber · 05-01-2016, 01:10 PM

Looking for some ideas on the cause. Car is leaving very lazy and has a hesitation at the hit of the throttle. It cleans up and runs strong after about 4,500 in first gear. Tried a spare carb, but unsure if it was good or not, and had the same results. Swapped converters to a known good one and replaced the ignition coil. The fuel pressure is staying steady at 7 1/4. The car is a 72 454 Corvette running in C/SA. The motor is fresh/new and was dynoed. Neither my carb or igntion were part of the dyno testing. Both sat for about a year without usage. Let me know if you have any ideas on what to look for/test. Thanks

Norm Webber

Bob Gullett · 05-01-2016, 01:38 PM

Try the fuel pressure at 6 psi for starters. Trans oil level is OK? If you use a 2 step change the 2 step module. Had one go bad when we had our Malibu stocker causing same grief.

Lee Valentine · 05-01-2016, 01:59 PM

Fuel sloshlng over?

nwebber · 05-01-2016, 02:08 PM

No on the fuel sloshing as it will act similar in park stabbing the gas. Checked the fluid and it is ok. I tried leaving without the two step and had the same results. I will try the fuel pressure on the next run. Thanks for the ideas

Terry Cain · 05-01-2016, 02:16 PM

Squiters doing as they should? Good flow out of both sides? Rear air flap OK?

Joe DeMarzo · 05-01-2016, 03:09 PM

Check the accelerator pump gasket, they dry out from sitting especially after using VP fuels. Chased that for a while once.

Eman · 05-01-2016, 03:48 PM

Described hesitation is usually too much or too little fuel. Too much and you'd get a black puff when it finally picked up. Too little and it's just a dead spot. I'd bet too little. I'd start by dissembling carb and cleaning thoroughly.
What carb does it have?

GTX JOHN · 05-01-2016, 06:12 PM

X2.............Sound like Carb.

older racer · 05-01-2016, 06:44 PM

how much timing are you using? where is your total set at ?what rpm? just curious

Adger Smith · 05-01-2016, 07:38 PM

Change the coil wire!

05-01-2016, 01:10 PM	#1
nwebber Junior Member Join Date: May 2007 Location: springfield OR Posts: 66 Likes: 1 Liked 35 Times in 2 Posts	Hesitation/lack of power Looking for some ideas on the cause. Car is leaving very lazy and has a hesitation at the hit of the throttle. It cleans up and runs strong after about 4,500 in first gear. Tried a spare carb, but unsure if it was good or not, and had the same results. Swapped converters to a known good one and replaced the ignition coil. The fuel pressure is staying steady at 7 1/4. The car is a 72 454 Corvette running in C/SA. The motor is fresh/new and was dynoed. Neither my carb or igntion were part of the dyno testing. Both sat for about a year without usage. Let me know if you have any ideas on what to look for/test. Thanks Norm Webber __________________ Norm Webber

05-01-2016, 01:38 PM	#2
Bob Gullett VIP Member Join Date: Mar 2002 Posts: 1,069 Likes: 41 Liked 413 Times in 92 Posts	Re: Hesitation/lack of power Try the fuel pressure at 6 psi for starters. Trans oil level is OK? If you use a 2 step change the 2 step module. Had one go bad when we had our Malibu stocker causing same grief. __________________ 68 Chevy11 327 F/S Last edited by Bob Gullett; 05-01-2016 at 01:46 PM.

05-01-2016, 01:59 PM	#3
Lee Valentine Senior Member Join Date: May 2004 Location: Brookfield, CT Posts: 708 Likes: 13 Liked 322 Times in 68 Posts	Re: Hesitation/lack of power Fuel sloshlng over? __________________ Lee Valentine 1661 STK

05-01-2016, 02:08 PM	#4
nwebber Junior Member Join Date: May 2007 Location: springfield OR Posts: 66 Likes: 1 Liked 35 Times in 2 Posts	Re: Hesitation/lack of power No on the fuel sloshing as it will act similar in park stabbing the gas. Checked the fluid and it is ok. I tried leaving without the two step and had the same results. I will try the fuel pressure on the next run. Thanks for the ideas __________________ Norm Webber

05-01-2016, 02:16 PM	#5
Terry Cain Senior Member Join Date: Feb 2008 Location: Georgetown, Indiana (close to Louisville, KY) Posts: 760 Likes: 492 Liked 224 Times in 103 Posts	Re: Hesitation/lack of power Squiters doing as they should? Good flow out of both sides? Rear air flap OK? __________________ Terry Cain ???? STK tcain@twc.com

05-01-2016, 03:09 PM	#6
Joe DeMarzo Senior Member Join Date: Oct 2002 Location: Mahopac, NY Posts: 666 Likes: 48 Liked 114 Times in 9 Posts	Re: Hesitation/lack of power Check the accelerator pump gasket, they dry out from sitting especially after using VP fuels. Chased that for a while once. __________________ Joe DeMarzo 1317 STK

05-01-2016, 03:48 PM	#7
Eman Member Join Date: May 2014 Location: E TN Posts: 441 Likes: 14 Liked 105 Times in 60 Posts	Re: Hesitation/lack of power Described hesitation is usually too much or too little fuel. Too much and you'd get a black puff when it finally picked up. Too little and it's just a dead spot. I'd bet too little. I'd start by dissembling carb and cleaning thoroughly. What carb does it have?

05-01-2016, 06:12 PM	#8
GTX JOHN VIP Member Join Date: Jun 2009 Location: Boulder City, Nevada 89005 Posts: 2,530 Likes: 2,222 Liked 1,807 Times in 572 Posts	Re: Hesitation/lack of power X2.............Sound like Carb. __________________ John Irving 741 Stock 741 Super Stock

05-01-2016, 06:44 PM	#9
older racer Member Join Date: Aug 2010 Posts: 203 Likes: 2 Liked 57 Times in 23 Posts	Re: Hesitation/lack of power how much timing are you using? where is your total set at ?what rpm? just curious

05-01-2016, 07:38 PM	#10
Adger Smith VIP Member Join Date: Dec 2001 Location: Texarkana Ark/TX Posts: 2,348 Likes: 434 Liked 676 Times in 260 Posts	Re: Hesitation/lack of power Change the coil wire! __________________ Adger Smith (Former SS)