Low idle, missing
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Yeah, I wish I would have drawn that conclusion a long time ago! I was too concerned with vac leaks/lean condition vs ignition problems too consider a problem with too much gas! I'm great a repairing vehicles, just not so much at diagnosis... that's what separates the shade tree from the real mechanic!
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So, here's a question before I open up my carb... what are all the possibilities for a carb to suddenly run rich? Aside from jetting or metering rods, my best guesses would be a sunk or out of adjustment float, or possibly a metering rod that is stuck down. If there are any other potential things to check please let me know and I will check them out or clean them
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Actually, a metering rod stuck down will lean things out rather than make it rich since the larger part of the rod will be in the jet. You can see that on Page 3 of the manual.
But, if the problem is running rich at idle the jets and rods don't come into play - as shown on Page 2. Just the idle jet and idle air bleeds, both of which are fixed, and the idle air screw. So, too much fuel and not enough air means either the float level has gone high or the air passage for the mixture screw is plugged. You've blown air into the idle air screw's hole, which should have cleaned out the passage, but it might not. So you could hit it with more air.
On the float, they can leak and sink. It happens very rarely, but it happens. However, did you change the fuel pump recently? Edelbrocks don't like more than 6 psi of fuel pressure or the float can't shut off the flow and the level of fuel gets too high, causing a rich mix - usually at idle.
But, if the problem is running rich at idle the jets and rods don't come into play - as shown on Page 2. Just the idle jet and idle air bleeds, both of which are fixed, and the idle air screw. So, too much fuel and not enough air means either the float level has gone high or the air passage for the mixture screw is plugged. You've blown air into the idle air screw's hole, which should have cleaned out the passage, but it might not. So you could hit it with more air.
On the float, they can leak and sink. It happens very rarely, but it happens. However, did you change the fuel pump recently? Edelbrocks don't like more than 6 psi of fuel pressure or the float can't shut off the flow and the level of fuel gets too high, causing a rich mix - usually at idle.
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I took the carb off today. The floats are good, and they are adjusted properly for the most part. I don't have a lot of time to mess with it on my work days, so tomorrow or the next day I will blast out all of the passageways with carb clean and compressed air. Yes, the idle mixture screws were adjusted last may when I rebuilt it. They were adjusted the way I always have adjusted them, screw it in until the idle rises, if it drops screw out until max rpm is found.
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Look for any rust particles or fine dirt in the bottom of the fuel bowl when you take it apart. If you see any fine particles in the bottom, that means there is dirt in the fuel and the carb is trying to ingest it. This can make the float needle hang open some and the fuel level gets too high, making the carb run rich.
I would check your fuel filter. Dump it out on a clean rag. If it's full of junk, I would buy a new fuel tank and get a new filter. If the tank is rusty I would not rely on the fuel filter to clean it up, a little bit always seems to get by them when the fuel supply is really dirty. Rusty tanks are a common problem on these trucks.
I would check your fuel filter. Dump it out on a clean rag. If it's full of junk, I would buy a new fuel tank and get a new filter. If the tank is rusty I would not rely on the fuel filter to clean it up, a little bit always seems to get by them when the fuel supply is really dirty. Rusty tanks are a common problem on these trucks.
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Well, I cleaned the carb sprayed every passageway out and blew them out with compressed air. I also adjusted the floats. still runs exactly the same. Now I'm at a total loss for what to check next. Fuel pressure is good, fuel flow is good. Ignition is good.
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Bummer! I'm at a loss to know what the problem is. To make sure I understand, the engine was running fine and then suddenly started running rich.
Hmmm. Just had a memory. I got bad gas in 1969 in my 1969 Super Bee. It put some sort of film on the needles of the Holley that didn't allow them to seal, and the carb was pig-rich. I ran multiple cans of gas cleaner in that tank and still had the problem. We burned that tank out and we're still having problems until we stopped at a rest stop and I pulled the carb apart and wiped the needles off with a clean towel. That did it.
So, when you had the carb apart did you inspect the needles? Wipe them off?
Hmmm. Just had a memory. I got bad gas in 1969 in my 1969 Super Bee. It put some sort of film on the needles of the Holley that didn't allow them to seal, and the carb was pig-rich. I ran multiple cans of gas cleaner in that tank and still had the problem. We burned that tank out and we're still having problems until we stopped at a rest stop and I pulled the carb apart and wiped the needles off with a clean towel. That did it.
So, when you had the carb apart did you inspect the needles? Wipe them off?
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Okay, so I was poking around the engine compartment... verifying timing (10 btdc) and double checking other items. I decided to put the spark tester on it and the sparks are orange. So I gather that I have weak spark. So, I suppose I oughta test the coil again and check the voltage at the coil.
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When I had the carb off I tore it all the way down and cleaned and inspected everything. It was pretty clean inside already and everything looked fine. The floats were a hair out of adjustment but that's pretty much all i found. Yes, my truck was running great and then one day it just started idling low, missing, and sounds lopy at idle. It does not run right off idle either. I assumed it's running rich because when I pull a large vacation line it runs quite a bit better... if it was lean from a vac leak it should run worse. Now today I found that I have a weak orange spark.