I have a 1982 4.2L (255) V8 with a 2BBL Autolite carb (E2WE-EA) and AOD transmission. It was bogging out when I accelerated or it changed gears and I had to pat the accelerator to get through it bogging. Sometimes it would stall. I purchased a kit and rebuilt the carb but it has the same problem. I haven't found any vacuum leaks. When parked it idles fine, vacuum steady at 18 in.Hg. When you throw back on the throttle it bogs and eventually gets through it, vacuum drops as it accelerates, or dies. When driving it doesn't get through the bog or stall and usually dies, then it's hard to start. I don't think it's the fuel pump because when in park it does accelerate and run okay at a high RPM once you get through the bog. The EGR is fine and I have tried plugging different vacuum lines to see if it had any effect, but didn't. Timing is dead on 8 BTC. Have replaced ICM, distributor cap/rotor, pickup, etc. Any ideas? Thanks for any input!!!

 

I think I would check the fuel pressure. It still could be a bad pump or possibly a fuel filter plugged.

 

Thanks Hreed.
I will do that tomorrow. I also will try temporarily disconnecting the exhaust to see if the catalytic converter is clogged. Thanks again and take care!

 

Is the timing reading with or without the vac advance connected? The vac hose should be disconnected and plugged to get the proper reading. IIRC, these engines used manifold vacuum for the distributor, and that would be consistant with the problems you are having.

 

Thanks Ford Six.
After all day being frustration I'm no better off. I pulled the cat off and have the same problem. I tried plugging various vacuum lines with no luck. Checked timing and tried advancing and retarding, then back to exactly 8 BTC. It looks like the vacuum advance is working correctly. I even tried rerouting the vacuum advance to bypass all the other vacuum components and tying it directly into the manifold port, but no difference. The pick up, cap, and rotor all still look fine. I changed plugs and gapped per specs. I took the carb apart again and verified everything was clear, working, and set correctly. It's the stock 2 BBL with 50F jets (number on the jets) and I still believe that since the car's doing the same thing it was before I rebuilt it I'm going in the wrong direction. Made sure wet float level was exactly where it's suppose to be, 7/64. Checked fuel pump pressure and found it's within specs, 7-8 PSI. The pump is less than a year old. Looking down the carb throat when pulling back on the throttle I verified it's getting plenty of gas, doesn't appear to be a float or fuel delivery to the carb problem, and wondered if it's too much gas too soon. Doesn't appear to be flooding or starving so the float must be right From what I can tell it's almost as if the gas is being dumped in too fast to start with and then the engine will catch up, don't think it's the carbs fault. This is on a fairly steady pull back of the throttle. If I pull back real quick it revs right up. That does sound like a vacuum advance problem but as I said I'm pretty sure that's working okay? The lag/bog/loading is still really an issue when the AOD transmission shifts and the motor bogs/lags/loads. I'm at a loss as to what to do next, besides see if a professional can figure it out. I still would appreciate any input into possible causes. I have searched about every post on the web that had similar problems, anything even close. Thanks again.

 

I don't know what the 4.2L spec is, but 18" sounds a little low, implying a small leak. When you ramp up to 2500 rpms in neutral does the vac drop real low? (Say 5"?)

The vacuum drop is the key there. If the air stops moving any fuel squirted in is going to be too much fuel. It sounds like an intake manifold leak. Possibly combined with the AOD shifting late or maybe early. As a test, I'd get it good and warm and shut down ALL the emission controls with the cat disconnected. AIR, EGR, all of that, and just leave the advance hooked up. (Is the heat stove opening and closing?) Is it still at 18"? Is the break booster leaking? Is it hissing inside the car when you step on it?

I'd also unplug the vac advance, and check for mechanical advance. (Rev it up with the timing light on it. Is it advancing? A lot?)

(Ok, really wild idea. Has it got an accelerator pump on it? You could disconnect that (it don't run right nohow anyways) and see if that leans it out enough to get past the bog. (And watch the vac!) If it's a bad leak, I'd expect it to stall completely first time you stepped on it. Bang, no fuel. Either that, or if the vacuum is high enough to move some fuel it leans out enough and maybe runs better. That's not a fix.)

ash
['Sounds annoying.']

 

I wonder if the timing chain has jumped a tooth. This can make it pretty sluggish.
Have you done a compression test on the engine?

 

I have 72 f250 that is exactly the same. Have done the same thing you have. I have a 100% tune up, timing corect, all new fuel filters,new carb,checked vacuum (18), and I am at a complete loss of why i burps back to me when I hit the pedal. But when it shifts into 2nd it really picks up speed real good, (C6 trans.) My truck has been bored out and also has headers. I dont know what to do next, ( about ready to shoot it).

 

Mine is doing the same thing, I have a 1978 F-100 custom 300ci. auto.after replaceing ---- im left with egr valve I had to order it, it should take about 3 days to get here. After being stuck down the road I just happened to grab hold of the EGR valve and it was loose, the front half, and it started to shutter even worse.I hope this is it, it's as old as the truck, don't know if that means anything. When I get it in I will post and let you know. Don