Rough Idle/Running

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LJS30

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Hey gentlemen my recently rebuilt 318 has been running great until about three hours ago. For some reason upon hot start up it coughed, stalled, and the proceeded to run rough for the next fifteen minutes I drove it. I smelled gasoline so I thought perhaps I flooded it. However, this car hasn't been used in a long time until now and I recently filled up the gas tank. Could some sediment from the tank possibly be in the filter?
 
Possible sediments but not likely from just one tank of fuel,it would needed to be nearly clogged before.Sounds more like the needle valve has trash in it or the old gas has coated the tip and is flooding the carb.Only other thing I can think of is bad gas in the bowl but 15 mins would have flushed that out.
 
OldmanRick said:
mopar410 said:
Sounds more like the needle valve has trash in it or the old gas has coated the tip and is flooding the carb.

73AbodEE said:
sounds like a float stuck (needle and seat), tap on the float bowl, i bet it runs good again.

Sounds like these^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^are the likely problem.

What carb do you have?
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The carb is an Edelbrock 650. On my way out right now it did it again upon warm start up. I think there is an issue with my mixture because I have to give it a slight bit of gas to start or else it just cranks. Then once it fires it's real rough and almost stalls out. After about a minute it's okay.
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It sure sounds like a carb issue. If you don't get anywhere with that, i'd look at the coil/spark.
 
Is the choke closing too much possibly not letting enough air into the motor? Try cold-starting it with the choke wired fully open and see if that helps. I just went through hell with an eddy 1406 600cfm carb and fixed that problem with a 650 Holley double pumper.
Everything I've read about the eddy carbs indicates they are calibrated waaaay to the lean side. But the fact that it ran great then is having problems all of a sudden points to some kind of clog/debris issue in the carb, IMO. Eddy's have tight clearances in the metering system (rods and jets) and I feel that they are very sensitive to debris going through them. Just a thought.
 
LJS30 said:
The carb is an Edelbrock 650. On my way out right now it did it again upon warm start up. I think there is an issue with my mixture because I have to give it a slight bit of gas to start or else it just cranks. Then once it fires it's real rough and almost stalls out. After about a minute it's okay.
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i would just take it off and have a looksee in the float bowls, blast the thing with carb cleaner and check floats for drop. clean the needles, seats, jets and metering rods, then put it back together. it could be the idle circuit is dirty. it could also be a fuel pressure problem.

do you have an electric pump, gauge or regulator?
 
73AbodEE said:
i would just take it off and have a looksee in the float bowls, blast the thing with carb cleaner and check floats for drop. clean the needles, seats, jets and metering rods, then put it back together. it could be the idle circuit is dirty. it could also be a fuel pressure problem.

do you have an electric pump, gauge or regulator?
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I have the stock mechanical pump. It's actually getting worse so I may have to park the Dart in my barn and clean out the carb.
 
Badsport said:
Water in the fuel?? Did you fill up somewhere out of the norm?
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Nope but the car had been sitting for a long time while the motor was getting rebuilt. I say that because I'm talking a LONG time since my mechanic/friend did it on the side of his normal jobs.
 
Back to picking up something in the tank. If you have a pretty good length of fuel line ( 4-5 feet) you could hook it up to the pump and run it under the front of the car away from the engine compartment and pump some gas into a glass jar and look for sediment and water (let it sit for a bit gas will rise to the top if there is water) if by chance you got bad gas. Just make sure you get it out of the engine compartment so there's less risk of ignition.

If you find sediment, cut the filter open and look inside. Very possible that's the problem.
 
My mechanical pump would run but would randomly stall.After a new one I could tell a huge difference in pumped volume.So make sure your pump will fill the bowl in a few seconds of cracking
 
Take off your air filter, and start the car. Look down the throat of the carburetor while it's running. if the choke is closed, push it open with your finger. Take a flashlight, and see if any part in there is wet. at idle, everything should be bone dry. If you notice anything is wet, the carb is running over and you need to mess with your needle and seat.

Also, if everything looks dry, cut the car off and look back down the throttle bores. Still, everything in there should be dry. If there's fuel visible, you've got a running over problem.

I had a problem like this with the carter avs on my 318. Turned out, when I rebuilt the carb I didn't snug down the seats well enough, and they got loose after a few weeks of driving. You've probably just gotten some trash in the seats, and a squirt or two of carb cleaner will make it right as rain.
 
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