Running Rough . . . . But Only Sometimes . . . . .
Thread Starter
Racer
Joined: Aug 2007
Posts: 290
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From: Marietta GA
Running Rough . . . . But Only Sometimes . . . . .
Help, please!! Our '74 has had intermittent problems with running rough. Usually runs fine cold, but sometimes when it gets hot, it'll run rough and stall out when stopped. Thought we had figured out the problem (loose spark plug wires) and it ran fine. Took it to a mechanic to check the timing and the tach - the timing was fine, but it started running rough again. Found another loose spark plug cable (think the mechanic knocked this one loose). Ran GREAT for the past 3 weeks or so, even on longer trips of a couple of hours. Took it to Firestone Friday for an oil change (cheaper than we could do it!) - yup, started running rough again. Decided to replace the plugs and wires, and found a bad spot on one wire. Not the problem. Checked all the vacuum hoses, t-connectors, etc. - no leaks. Choke is working fine. Air filter is clean. When it's running fine, the idle is around 700-800 RPMs, but when it's running rough, the idle drops below 500 and it has backfired a couple of times. Any suggestions??? Is there maybe a vacuum cap hidden somewhere that maybe we missed?
UPDATED TODAY, 10/14 - SEE POST #22
UPDATED TODAY, 10/14 - SEE POST #22
Last edited by suzie-q; Oct 14, 2007 at 08:26 PM.
Racer
Joined: Nov 2003
Posts: 386
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From: Grafton WV
I just fixed a problem on my 81 and it was the spacer between the bottom of the carb and the intake manifold had a big piece of it blown out. Created a hell of a vacuum leak and it would not idle but this was all the time it would run terrible.
New spacer and it runs great again Yeee Hawww
New spacer and it runs great again Yeee Hawww
Thread Starter
Racer
Joined: Aug 2007
Posts: 290
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From: Marietta GA
Glad yours is running good again, Yeller81USNRet! Pretty sure it's not the spacer since it happens only once in awhile. For example, yesterday it ran fine on our way to an event, but from there to the restaurant and then back home again, it ran really ragged. Tried to stall out at every stop we made. After we changed the plugs and wires, it still ran rough. Today we couldn't MAKE it happen. Really hard to troubleshoot!!
Anybody else have any ideas??? Thanks!
Anybody else have any ideas??? Thanks!
Thread Starter
Racer
Joined: Aug 2007
Posts: 290
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From: Marietta GA
Interesting you should mention the fuel filter - just said to my hubby tonight that maybe we should change it just in case it was gunked up. The carburetor is fairly new - the last owners had replaced it, but the car sat more than it was driven. Would sitting like that cause it to stick? If so, what do we need to do to fix it?
Thread Starter
Racer
Joined: Aug 2007
Posts: 290
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From: Marietta GA
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Pro
Joined: Jun 2005
Posts: 725
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From: FL.
OK, check the float level, one or both May not be seating tight, lets in too much fuel and the engine will want to crap out and die. Check the floats, the old style cork types can get soggy and start sinking, same thing..cant stop the fuel from filling the bowls, and engine wont run right. Reset the float level while your in there..then if alls well then you can rule out float bowl problems and move on..Youll find the problem eventually and have a complete tune up done too
Thread Starter
Racer
Joined: Aug 2007
Posts: 290
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From: Marietta GA
OK, check the float level, one or both May not be seating tight, lets in too much fuel and the engine will want to crap out and die. Check the floats, the old style cork types can get soggy and start sinking, same thing..cant stop the fuel from filling the bowls, and engine wont run right. Reset the float level while your in there..then if alls well then you can rule out float bowl problems and move on..Youll find the problem eventually and have a complete tune up done too
Thread Starter
Racer
Joined: Aug 2007
Posts: 290
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From: Marietta GA
<Edit> Duh! What was I thinking?? That was the FIRST thing we replaced!!
Last edited by suzie-q; Oct 1, 2007 at 06:33 PM.
Intermediate
Joined: Sep 2007
Posts: 38
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From: Clarksville Tn
Might want to also replace the coolant sensors and wires if you have them. I had the same exact problem. Also check your intake you may have a small water leak and catching an air bubble around the sensor
Melting Slicks
Joined: Dec 2006
Posts: 2,669
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From: Kingston Ontario
Sounds like it is running fine when cold. I would double check the choke operation and make sure it's fully opened when warmed up and that the linkage is not binding (because of insufficient lube or linkage making contact with filter housing, etc.) causing intermittent problems.
Thread Starter
Racer
Joined: Aug 2007
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From: Marietta GA
Thanks!
Thread Starter
Racer
Joined: Aug 2007
Posts: 290
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From: Marietta GA
Sounds like it is running fine when cold. I would double check the choke operation and make sure it's fully opened when warmed up and that the linkage is not binding (because of insufficient lube or linkage making contact with filter housing, etc.) causing intermittent problems.
Thanks!
Intermediate
Joined: Sep 2007
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From: Clarksville Tn
i would still chech into the coolant plugs and wires. After i went through and changed all the stated above distributor wires plugs even had the crossfire totally rebuilt I still had the problem. After talking to another mechanic buddy he told me to check the sensors and told me where they were. As soon as i grabbed the wire connectors they fell apart in my hand. So i traced the wires back to the point were they where not scorched clipped them and replaced the connectors and the sensors themself and i haven't had the problem sense.
Intermediate
Joined: Sep 2007
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From: Clarksville Tn
[QUOTE=Bob Onit;1562133970]What sensors are you speaking of?[/QUOTE
These sensors I'm speaking of, one is located toward the front of the enigine block on the right hand side just under the head and the other is on the left hand toward the rear of the block in around the same as the other. Both having a single lead wire. But as I said in one of my first response if you have them that would be the area to check. Being that there Vette is almost 10 years older then mine.
These sensors I'm speaking of, one is located toward the front of the enigine block on the right hand side just under the head and the other is on the left hand toward the rear of the block in around the same as the other. Both having a single lead wire. But as I said in one of my first response if you have them that would be the area to check. Being that there Vette is almost 10 years older then mine.
Thread Starter
Racer
Joined: Aug 2007
Posts: 290
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From: Marietta GA
These sensors I'm speaking of, one is located toward the front of the enigine block on the right hand side just under the head and the other is on the left hand toward the rear of the block in around the same as the other. Both having a single lead wire. But as I said in one of my first response if you have them that would be the area to check. Being that there Vette is almost 10 years older then mine.