Help, car surging

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Tool505

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Have apprx 100 miles on fresh 360 magnum in my 74 dart. Has eq heads with la intake, edelbrock 1806 carb. Has been running good, took it our tonight and on the drive home it start backfiring and surging. Wideband shows it's going really lean into the 19's and surges back and forth. Brand new edelbrock performer mechanical fuel pump in it and shows fuel in filter. Where do I start ran perfect last wkd and on 20 min drive to dinner but this started on way back home
 
Fuel supply problem of some sort. Start with a pressure gauge on the pump.
 
I'm getting vapors out the carb after getting it home and opening the throttle. Would this be vapor lock
 
Another tough one. Any chance you developed a major vacuum leak somewhere? Does she have power brakes?
 
I'd say dirt in the carb or you got some bad gasoline.

Either way I start by dumping in two bottles of gumout in the tank.


I personally only use the real gumout brand and buy the cheap stuff with the white lable
 
No vac leak. Fresh gas. I can try the gum out and I just ordered a fuel pressure gauge and regulator so I will give that a try. Thanks
 
Id say picked up a piece of debrit of some sort. I ran into same problem a few yrs back. When i pulled the carb apart there was all kinds of debrit as well as a yellowish shellack appearing coating. Got to love this awesome gas.
 
Did you change out your fuel sender/pickup? May have a hole in the pickup tube if its an old original one. Diagnosis is to fill up, see if it runs fine till a certiant point in the tank, then runs like crap. Fill back up and if fixes it.

Just something to throw out there.
 
I'd say start with checking your initial timing, maybe a bad float or junk in the needle and seat.
 
Filter had some black particles in it, pulled carb, cleaned and blew out everything an found more black stuff inside the carb, blew out the fuel line to carb and car still runs lean and putters. It will idle but you can hear and see on the wideband it's wanting more fuel. Fuel filter filled right up, I can see fuel squirt into the carb and timing is at 10 initial for motor break in right now. Fuel pressure gauge will be here in a couple days. New pump taking a **** and not getting enough pressure is all I can think off now.
 
Make sure your adjustment screws on the carb didnt get turned or vibrated.
 
Hard to believe that carb is going lean with 8.5lbs. The hard part to deal with is it ran good for a time and then acted up.......I almost wonder if it could be a intake valve adjustment problem? I know I'm thinking a little out of the box, but could the preload be a little tight and with heat/expantion and lifter pump up, that the intakes are hanging a open a hair? Like I said, I'm just looking for something that most wouldn't think of?
 
Debris in low speed circuit. Remove mixture screws and gently blow out circuit. Make sure float bowl is vented when you do this.
You should probably clean out the bowls again.Any chance that black junk is from a rotten fuel line? say at the back?
Check/replace your fuel filter as well.I mean that junk came through it, right?
 
AJ/FormS said:
Debris in low speed circuit. Remove mixture screws and gently blow out circuit. Make sure float bowl is vented when you do this.
You should probably clean out the bowls again.Any chance that black junk is from a rotten fuel line? say at the back?
Check/replace your fuel filter as well.I mean that junk came through it, right?
Click to expand...

X2 on rotting fuel line. Local speed shop owner said even stainless braided lines have been giving people fits if the inside is black rubber...new fuel eating it up. Good luck!
 
AJ/FormS said:
Check/replace your fuel filter as well.I mean that junk came through it, right?
Click to expand...

One of the very first things that should have been checked.
Also just because there is pressure does not mean there is volume.
 
8.5 lbs of fuel pressure is too high anyway. optimum fuel pressure for that carb is 5.5. probably pushing gas past the needle and seat
 
73AbodEE said:
8.5 lbs of fuel pressure is too high anyway. optimum fuel pressure for that carb is 5.5. probably pushing gas past the needle and seat
Click to expand...

That is true Lance, but I don't think that is his immediate problem. (way lean)
If there's black junk in his carb then there is a filter/fuel line disintigration issue somewhere.
 
What Aj said, I would take out the (2) idle mixture screws and shoot a healthy 3 second blast of starting fluid into each hole with the thin red straw then replace the screws. Count the # of turns to lightly seated before removing them to easily/quickly return em to their orig setting when done. this will take you 2 minutes. no go then I'd confirm no vac leak then start checking out the ign in spite of what the A/F ratio is telling you. Keep us informed!
 
Just for kicks try disconnecting vacumn advance and plugging both ends, only takes a second and doesn't cost anything. Had a couple of my cars ( both Mopars ) that instantly ran perfect when they were running like crap.
 
check your plugs they might be loading up, mine did that and cleared right up after changed plugs
 
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