Mid throttle Hesitation

[Joop]

Hey there, I have found myself here as a last resort because I can't figure out the probelm with my 67.

It's a 289 and the problem is that when I step on the gas, especially at half throttle, there is a hesitation and sputtering that is robbing my power, as you can imagine, it sucks.

Things I have tried:
First I gave it a tune up since it was sitting for the whole winter; new plugs, wires, points, distributor cap, rotor and cleaned the carb.

Then my buddy noticed that the linkage to my accelerator pump was missing. Replaced that.

Went on to replace the stock fuel pump with an edelbrock, better but not totally.

Finally, I put in another fuel filter even though I replaced it last fall. Still not running right.

I now have this GUMOUT stuff that you put in the tank to get rid of any crap thats floating around in there, didn't put it in yet, gotta wait for it to be close to empty.

So is there anything I'm missing? I can't figure out what is causing this but any help would be greatly appreciated.

Oh and the accelerator pump linkage is in the center hole of the plunger, don't remember what it was on before but could that be part of it? Its an Edelbrock 500 4BBL.

Thaniks in advace!

Joop

 

[Capt Dan]

did you replace the accelerator pump or just the linkage?

 

[Joop]

Just the linkage, i have an extra plunger too that isn't being used. The Carb is only maybe 3 years old.

 

[krash kendall]

Did it run well when parked? How's your timing? Is it still full of last years gas?

 

[Joop]

It runs great at idle, this started last fall right before I put it away but I didn't have time to fix it. I have been through 3-4 tanks already. I havn't done the timing since the engine was rebuilt 3 years ago.

 

[12sec67]

did you try to adjust the accel pump using the 3 holes?

 

[Joop]

did you try to adjust the accel pump using the 3 holes?

No thats one thing I was unlear on, is that part of tuning the carb? I guess it's worth a shot, I'm still learning about adjusting carbs I guess, I just assumed the bottom hole pushes the plunger deeper which in turn uses up more gas... Then again I could be an idiot. Would it be worth looking at a buddies mustang? Or are they all different.

 

[67coupe351w]

No thats one thing I was unlear on, is that part of tuning the carb? I guess it's worth a shot, I'm still learning about adjusting carbs I guess, I just assumed the bottom hole pushes the plunger deeper which in turn uses up more gas... Then again I could be an idiot. Would it be worth looking at a buddies mustang? Or are they all different.

It does use more gas if its on the hole that pushes the plunger in farther but if the engine hesitates when you mash it to the floor, then you probably need to bump it up a notch.

 

[Joop]

Well it doesn't hesitate when I floor it, its when I am going around 50-60... gas only pressed down half way, when it hesitates the most. I'll try to adjust that linkage today and see what happens. But if there are any more suggestions, I'm always listening. Thanks.

Joop

 

[Kriek]

Did adjusting the accelerator pump linkage help?

 

[Joop]

Adjusted the linkage to the top hole and it runs great now... Guess it was getting too much gas in the carb. Thanks!

Joop