HELP!!! Not Running Good??

[RRcrazy]

Ok guys help me figure this out.

1970 Roadrunner
383 (.40 over)
4 Speed
Holley 750 DP
Electronic Ign.

The other day I noticed a miss, so when I got home I tried to locate the cylinder that was misfiring by pulling each wire while the car was running but did not find the problem cylinder. I remembered the miss happened when I was going up a small hill so I thought to check the float levels one was a little low so I adjusted until it dribbled out of the inspection hole. Still missing.....the car idles fine and revs freely. But when the car is under and load it starts to miss and the miss is getting worse. I have since changed the coil, the cap, rotor. The problem is still there. I'm wondering if its bad gas. . . my tank is pretty low less than 1/4 of a tank. Could it be electrical going to the coil, The Ignition, The carb???

What do you guys think??

Thanks.:icon_hang:

 

[wannadrag]

Fuel filter or the sock on the pickup in the tank?

 

[67 coronet]

an under load miss or bog is normally one of several problems,
1)fuel delivery,as wannadrag said.
2)timming,or advance specifically.
3)carb my have problems or need rebuild.
check those first.fouled plug may cause the problem occationally as well.

 

[moparstuart]

you could have a spark plug wire arcing also , I had one doing that under load , Bought those nice expensive fire core wires and protective socks for the plug boots by my headers never happened again .

 

[RRcrazy]

Draining all the fuel

an under load miss or bog is normally one of several problems,
1)fuel delivery,as wannadrag said.
2)timming,or advance specifically.
3)carb my have problems or need rebuild.
check those first.fouled plug may cause the problem occationally as well.

Pulled some gas out of the tank last night put it in a clear jar and let it set. This morning I saw a seperation of gas on top and what looks to be water below. Only about 1/16 of an inch but I'm going to drain the gas and put new gas in to see if that is the problem. I just got this car about a month ago and never had the gas level this low before one notch above E. And never had this problem before until now. What do you guys think?

 

[67 coronet]

Pulled some gas out of the tank last night put it in a clear jar and let it set. This morning I saw a seperation of gas on top and what looks to be water below. Only about 1/16 of an inch but I'm going to drain the gas and put new gas in to see if that is the problem. I just got this car about a month ago and never had the gas level this low before one notch above E. And never had this problem before until now. What do you guys think?

make sure to flush the lines and carb as well.hope it is just water.no sediment in what you pulled out,is there?

 

[RRcrazy]

UPDATE>>>UPDATE>>>UPDATE

Good News..., the problem was a short in the engine wiring harness. I just so happened to have had one on order from Evans that I got a couple of days ago. So my wife and I put it on this afternoon and the problem went away. Now I just have to figure out why my gas gauge stopped working. I'm also having a hard time getting the timing right. Suggestions appreciated.

Thanks for all the help.

 

[mzizzi]

the gauge might be dead because of a disconnect at the tank or on the plug to connect the harness in the rear to the dash harness, check behind the dash to see that everything is still connected, check yer fuses. i can't imagine this being it, but draining the tank dry could have somehow messed with the float inside (highly doubt it, but all else check there too). when doing timing the trick is do small changes and to do only one change at a time. start from scratch, timing at factory spec (I'm ashamed to say i can't remember mine own 383's spec timing, so look it up). if she won't catch, advance the timing until she fires. pull the vacuum advance plug from the carb, then set it again until it fires, plug it back in and then undo the timing until she runs clean, you may have to re-balance the carb tuning in some cases, but you don't mess with it i can't see a reason for it. see if that works. if not then, good luck

 

[RRcrazy]

the gauge might be dead because of a disconnect at the tank or on the plug to connect the harness in the rear to the dash harness, check behind the dash to see that everything is still connected, check yer fuses. i can't imagine this being it, but draining the tank dry could have somehow messed with the float inside (highly doubt it, but all else check there too). when doing timing the trick is do small changes and to do only one change at a time. start from scratch, timing at factory spec (I'm ashamed to say i can't remember mine own 383's spec timing, so look it up). if she won't catch, advance the timing until she fires. pull the vacuum advance plug from the carb, then set it again until it fires, plug it back in and then undo the timing until she runs clean, you may have to re-balance the carb tuning in some cases, but you don't mess with it i can't see a reason for it. see if that works. if not then, good luck

Found out that my car holds almost 5 gallons of fuel before it shows up on the gauge???? I put more gas in and the gauge came alive. Wow I cant believe that when it holds so much gas at E. Thanks for the timing info ....think my carb needs rebuilt thats why I cant get it dialed in.

 

[moparstuart]

most chysler senders work like that , they only go to 3/4 full and you still have a 1/4 tank when gauge reads empty . Drivers me nuts but all my cars do it .