WhiteLightnin83

ok i'm making the assumption that this is a problem with my carburator... when i'm goin down the highway say... 60 mph and i punch it, the car pukes hardcore and the rpm's dive down about 1500, then it comes to life like a bat out of hell.... but if i start from a stand still or i'm only going like 20 mph in first and stomp it then it goes just fine. so i'm wondering whats goin on exactly... i have a brand new edelbrock 750 on the car, anyone got any info for me?

'Shifter

iTrader: (2)

How's your fuel pressure? Any codes from the ECM? My '84
right off the showroom floor had a bad ECM and weak fuel pump,
and it did exactly as you describe.

dimented24x7

iTrader: (2)

Sounds like a possible pumpshot or tip-in fueling issue. Maybe too rich or lean. Any smoke in the rearview mirror when this happens?

WhiteLightnin83

what's an ECM? before the rebuild i never had such problems with it... i'll check tonight if it puffs smoke when i punch it or not... i have no idea about the fuel pressure cuz i dont' have a gauge for it...

Token

more than likely you're lean, caused by either a clogged fuel filter, bad fuel pump, or bad pressure. I dont think a vacuum leak would be this bad.



does it only happen at a specific time? IE when the car is warm or cold? Oxygen sensor could have a factor.

dimented24x7

iTrader: (2)

If it recovers and 'goes like hell' then its unlikely (but not impossible) that the pump is at fault. The pump is just keeping the bowl(s) topped off. If it never recovered then its a possibility. Unlike a carb, an efi setup with an in-tank electric can have problems like that as the injectors draw right off the pump with little or nothing to buffer the fuel demand.

It sounds like a fueling issue either related to how the carb is set up or possibly due to acceleration causing fuel starvation/flooding. I know zilch about carbs so I cant be of much help past that.

88Camaro350

Check and make sure your fuel bowls aren't to full. This could cause it to bog like this. Or you may have to much fuel pressure. Sounds like your carb is out of adjustment and just running to rich. Get a vacuum gauge and make some idle air screw adjustments. Then work on the fuel bowl level.

rx7speed

I agree either plugs or acel pump isn't setup right

trying romping on it a few times in a row then kill it while it's stumbling (yes that means while your still moving down the road to turn the key off) and take a look at those plugs


they could tell you lean or rich at the moment this is happening


but try adjusting the pump shot first then maybe try the second method above and see what it shows on the plugs


black and sooty too rich. nothing showing up on the plugs or a white powder on them and your prolly running a little lean




the only only other thing I can think of is timing and maybe something with the vac can but don't me to it and I'm prolly wrong on this one but figured I might bring it up

BballDad

Back in the day we would adjust the secondary butterfly floats to open sooner. If you got them to lose the thing would fall on its face like you described. This was how they varied the HP rating on similar models with basically the same engine and carb modes[some were set not to open up all the way limiting performance]. Try tweaking with the secondaries, first try tightening them up, sounds like they're opening to soon.

WhiteLightnin83

ok, thanks for all the info guys.... i think maybe hte carb was runnin a bit rich anyways so i'm gonna try to lean it out a little tonight if i get time. i don't honestly think it would be anything with the fuel pump or pressure becuase i had all that stuff on the motor before the rebuild and never had such problems... but its a possibility i'm sure, just not as likely as the carb not being tuned properly since i did just pull it out of the box and bolt it on....