Hi guys, having some issues with the Camaro. When going WOT the engine dies down for roughly 1 second and then goes... previous owner believed it was the colder weather and the carb needed to be tuned... now that the weather has warmed up a bit and the car is still doing it I think it is about time to figure out what it is making it do it. The engine runs fine at idle, and great through the whole power band, just the hesitation when going WOT. This is my first car with a carb so excuse me if I am dumb-founded on the topic... I do have a timing light but I don't think it is the timing... any thoughts?

... also the PO didn't run the wire for the choke... maybe it is engaged? Now I just have to find it and look....

What kind of carb is this? Are you running a stock pump, filter, etc...?

unfortunately I just recently acquired the car, so I am unsure of a number of things, basically starting from scratch! I will be getting in there later tonight and taking a look at what it has under there... and I will update when I know!

Had this trouble with a couple cars over the years. Fuel starvation. Pump not putting enough gas into the carb. Only real fix I came up with was an electric pump back at the tank pushing gas to the stock pump, turn it on when you need the extra fuel, use the regular pump normally.

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If it's a Holley, I would check on the pump & squirter.

I have no idea how the fuel pump has anything to do with a WOT one second hesitation when the bowls are already full???

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Holley carb and Edlebrock performer intake... I would be surprised if it was the fuel pump, when once at WOT it pulls and runs great through the whole band... but anything is possible :p

First, I would check to be sure the accelerator pump is properly adjusted. My next thought would be the secondary spring. this determines how quickly the secondaries open up when you punch the gas. If someone has played with springs, it might be opening the secondaries too late or too soon. either would give you the bog you describe. Of course, this latter assumes you have a vacuum secondary carb on the engine. check the accelerator pump first before getting into deeper components. Good luck.

Oops. I saw the die down for a second and get going and didn't really note the rest of it. Baby sitting last night. Need to read the post I guess. Sorry.

if it's a Holley, try increasing the squirter size...trial and error....find the one that works best. ;)

Not sure how accurate this is but a tuner shop tech guy told me this the other day. New Carbs/ Used Carbs are all having more issues now with the blended fuels being almost impossible to avoid. The ethanol is everywhere now and he said it alone is causing trouble in carbs that should be checked every off season now for pooched out O-rings/ seals and stuff. Anyone else followed this new fuel and troubles it might bring. I understood it to mean any rubber/ plastic in the carb exposed to ethanol has very short life now. Never really thought about it but how much rubber parts are in carbs.

I am not carb expert but thought I would share this.

Hey 80/ St. Thomas how is it going down there, any street cars on the road yet. Starting to see many more around town here now and why not when it hits into the 60's.

probrably just the adjustment of the pump arm or the timing of the power valve

after some research I think it is probably the arm for the accel. pump... going to pull her out of the garage today and start taking things apart, lol.

hmm... well I got in there today and the pump arm was a little loose, adjusted it but problem is still there, hesitation on WOT and an occasional backfire as well. :(

I see you're up there in the Blizzard belt. Is this a recent problem? How old is the gas in that machine? Been sitting all winter?

new gas, 93 oct... also just recently got the car, previous owner thought it was idle related.

hmm... well I got in there today and the pump arm was a little loose, adjusted it but problem is still there, hesitation on WOT and an occasional backfire as well. :(

I'll bet on power valve timing or ignition timing if the pump arm is good

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I never use PV's, and all my carbs usually have the big pump, so my issue is usually the squirter when I have your symptom.

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Sounds like a squirter issue, step up the squirter size and take 'er for a rip...still the same? Increase again until you reach the "sweet" spot.

Sounds like a squirter issue, step up the squirter size and take 'er for a rip...still the same? Increase again until you reach the "sweet" spot.

Thats what I am thinking... I am going to check the basics today, make sure mixture is good and floats are correct, then jump into the squirters.

Went from a 31 to a 35 nozzle, tuned the air/fuel mix and it seemed to be a little better, but the hesitation is still there... I have read a few different things on how to check/choose the correct power valve... does anyone recommend a certain way? I might step up to a 37 but jeez... that is a lot more than a 31!

Are you sure your timing is advancing at the proper rpms?

Went from a 31 to a 35 nozzle, tuned the air/fuel mix and it seemed to be a little better, but the hesitation is still there... I have read a few different things on how to check/choose the correct power valve... does anyone recommend a certain way? I might step up to a 37 but jeez... that is a lot more than a 31!

Don't be worried about using the 37 nozzle, that's the one that worked the best on my 650dp iirc.

Are you sure your timing is advancing at the proper rpms?

nope... not really, lol. New to the old car game... how would you recommend going about making sure it is advancing correctly? I do have a light, just need to know what I'm looking for.

Might throw a 37 in and see if that makes any difference... it did feel a little better and some of the hesitation is gone, so going to the 35 did something. And the nozzles are not expensive so its not too big of a deal.

Engine is holding around 17 for Vac in park and about 11/12 in gear. Also did the turn idle mix screw in to test and make sure the Power Valve is working and it killed the engine... so it is working, just don't know if it is the right one or not in there.

well, fired the car up today and it was running awful... no idea what happened, lots of hesitation, rough idle and was hard to start, wanted to start then die off in a few seconds... whats going on with this car??

edit:
Here is my check list for this weekend:
Make sure there are NO vac leaks
Check air/fuel again
Check floats again
Check timing
If all that fails then who knows!

well, fired the car up today and it was running awful... no idea what happened, lots of hesitation, rough idle and was hard to start, wanted to start then die off in a few seconds... whats going on with this car??

edit:
Here is my check list for this weekend:
Make sure there are NO vac leaks
Check air/fuel again
Check floats again
Check timing
If all that fails then who knows!

With this thing all over the place, it sounds more like an ignition timing issue than it does a carb issue. I would pull the dizzy for inspection/replacement (if required) before I did anything else. After that I would re-time the motor from scratch and go from there.

I know it would be a lot of work, but if the dizzy checks out fine, I would pull the timing cover and check for excessive play in the chain. Other than a bad dizzy, this is the only other thing that I can think of that will make the motor be all over the place with no rhyme or reason to its pattern.

OK update time! Checked for Vac leaks and found nothing, so that was good. Then for the heck of it, before switching to the 31 nozzle, I checked the air/fuel mixture and huh... one mixture screw was all the way in! That is what you get I guess for having a buddy turn the one screw while you turn the other telling him how far to turn it! Put both screws 1 1/2 out and car turned over first click... took it out for a drive and it was worlds better than the other day, the hesitation is still SLIGHTLY there, but it is the same off WOT hesitation, and it is MUCH better. Thinking now that a slightly larger nozzle will be rid of all the hesitation...

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That was an easy fix, now get it tweaked, and work on the squirter.
Don't worry about the squirter number, whatever it likes is what it needs.
I've used up to a 40 before to make it right.

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Update again, went up from the 35 to a 37 and tuned the air fuel mix again and like magic all the hesitation is gone! Thanks for the help guys :D