Bad idle, backfire
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Joined: Jan 2001
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From: Virginia
I was worried something was wrong with one of the vacuum controls or a vacuum line was in the wrong place, making your EGR come on prematurely. Apparently that is not the case.
In the post above he is thinking the dist may have something to do with it, so unplugging it may help it, may not.
You need to get the engine to communicate possibly what is wrong. Unplugging stuff and messing around with it and watching how it reacts can give clues as to what may be causing the problem. Spraying brake cleaner around the carb while it's running may give you a clue.
In the post above he is thinking the dist may have something to do with it, so unplugging it may help it, may not.
You need to get the engine to communicate possibly what is wrong. Unplugging stuff and messing around with it and watching how it reacts can give clues as to what may be causing the problem. Spraying brake cleaner around the carb while it's running may give you a clue.
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Joined: Jan 2001
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From: Virginia
This not getting any better. Right now, symptons:
Starts, will not idle at low rpm at all, press accelerator to bring up RPM (no tach) and stays there for a few seconds, then drops RPM to almost stalled and almost always goes back up in rpm and repeats. Surges like this.
What I have done:
Rebuild carb, replaced EGR valve, plugs, distributor cap, spark plug wires, fuel filter, replaced leaking fuel pump (about 6 months ago), . Checked and rechecked vacuum lines, stared at the chart under hood until I was dizzy.
This started after I rebuilt carb. So I removed carb (and made dry float adjustment that allowed it to start). Saw no other issues.
Starts, will not idle at low rpm at all, press accelerator to bring up RPM (no tach) and stays there for a few seconds, then drops RPM to almost stalled and almost always goes back up in rpm and repeats. Surges like this.
What I have done:
Rebuild carb, replaced EGR valve, plugs, distributor cap, spark plug wires, fuel filter, replaced leaking fuel pump (about 6 months ago), . Checked and rechecked vacuum lines, stared at the chart under hood until I was dizzy.
This started after I rebuilt carb. So I removed carb (and made dry float adjustment that allowed it to start). Saw no other issues.
FTE Legend
Joined: Nov 2015
Posts: 30,946
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From: Angier, NC
And he did say it started after the carb rebuild.
Wonder if a wrong gasket was used or put on wrong?
If pulling vacuum from the EGR & dist. didn't help and carb cleaner was a no go time to pull the carb off and go back thru it to make sure all passages are clean & open and all gaskets are just right.
Sometimes you cant get them to work right and you just have to throw in the rag and get a rebuilt.
Dave ----
Wonder if a wrong gasket was used or put on wrong?
If pulling vacuum from the EGR & dist. didn't help and carb cleaner was a no go time to pull the carb off and go back thru it to make sure all passages are clean & open and all gaskets are just right.
Sometimes you cant get them to work right and you just have to throw in the rag and get a rebuilt.
Dave ----
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Joined: Jan 2001
Posts: 56,999
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From: Virginia
I rebuilt one of these Ford 2bbls, and it would not run right after I did it. Come to find out I did not put the gasket in correctly underneath the main venturi assembly. I knew it was something I did, because it would at least run before I rebuilt it. It would not hardly run after I got done with it.
FTE Legend
Joined: Nov 2015
Posts: 30,946
Likes: 4,126
From: Angier, NC
I rebuilt one of these Ford 2bbls, and it would not run right after I did it. Come to find out I did not put the gasket in correctly underneath the main venturi assembly. I knew it was something I did, because it would at least run before I rebuilt it. It would not hardly run after I got done with it.
Dave ----
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Mountain Pass
Joined: Jun 2007
Posts: 117
Likes: 6
From: Fort Worth TX
OK, no change after plugging the line after pulling it off distributor. Did notice if I really crank it up in RPM it runs more or less steady. I've pulled the carb once to double check my work, and I'll do that again before throwing in towel.
I will work with adjustment screws, I did take notice of turns to go in on each, and set it that way after rebuild.
anyway, just a thanks right now for all the things to check.
I will work with adjustment screws, I did take notice of turns to go in on each, and set it that way after rebuild.
anyway, just a thanks right now for all the things to check.
FTE Legend
Joined: Nov 2015
Posts: 30,946
Likes: 4,126
From: Angier, NC
OK, no change after plugging the line after pulling it off distributor. Did notice if I really crank it up in RPM it runs more or less steady. I've pulled the carb once to double check my work, and I'll do that again before throwing in towel.
I will work with adjustment screws, I did take notice of turns to go in on each, and set it that way after rebuild.
anyway, just a thanks right now for all the things to check.
I will work with adjustment screws, I did take notice of turns to go in on each, and set it that way after rebuild.
anyway, just a thanks right now for all the things to check.
Once you have the motor running you should get it up to temp before making adjustments but sometimes you have to adjust just to keep it running to get up to temp.
Thing is you cant have the idle RPM too high or you are not on the idle system and the mixture adjustment screws will do nothing.
Dave ----
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Mountain Pass
Joined: Jun 2007
Posts: 117
Likes: 6
From: Fort Worth TX
I made some modest progress. It almost idles. Question, shouldn't both the screws be adjusted the same? or very close? I made it a lot easier on me when I got my 800 lumens bike headlight pointed at those screws. Much better than the trouble light I was trying to use. Then, I could adjust screws pretty precisely. Started at 1.5, then did 2. It's much better than it was, but I think I just need to keep screwing with it to get it to idle.
FTE Legend
Joined: Nov 2015
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From: Angier, NC
In a perfect world they should both be the same number of turns but if 1 is say 2 and the other 2 1/2 so be it as long as it runs smooth.
Don't know how you are checking what the motor wants, runs best but if you want to get fancy you can use a vacuum gauge along with a tach for RPM.
Once you have the highest RPM and vacuum readings turn each mixture screw in 1/8 to 1/4 turn. Think the book said 1/4 turn in for best lean idle. (I leave them at highest readings).
Dave ----
Don't know how you are checking what the motor wants, runs best but if you want to get fancy you can use a vacuum gauge along with a tach for RPM.
Once you have the highest RPM and vacuum readings turn each mixture screw in 1/8 to 1/4 turn. Think the book said 1/4 turn in for best lean idle. (I leave them at highest readings).
Dave ----
Thread Starter
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Mountain Pass
Joined: Jun 2007
Posts: 117
Likes: 6
From: Fort Worth TX
Right now, I am just trying to get it idle on it's own, without messing with idle speed screw. Hopefully screwing with the idle screws will get me there. If not, I guess I can run the idle up temporarily to spray around carb for vacuum leaks, tweak idle screws, check timing.
I can't find the timing marks, but that thing has a lot of grease built up, what is suggested to spray on there without harming the belts?
I can't find the timing marks, but that thing has a lot of grease built up, what is suggested to spray on there without harming the belts?
Moderator
Joined: Jan 2001
Posts: 56,999
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From: Virginia
Brake cleaner is good stuff and evaporates quickly.
Also keep in mind what was stated in a previous post; If you set the idle too high, your idle adjustment screws will have less or even no affect on the idle quality. It's the way the carb is made inside. So you can turn the idle up to make it run, but if your idle adjustment screws suddenly don't do much, the idle is too high. If that is the only way to make it run by itself, you still have a problem somewhere.
Also keep in mind what was stated in a previous post; If you set the idle too high, your idle adjustment screws will have less or even no affect on the idle quality. It's the way the carb is made inside. So you can turn the idle up to make it run, but if your idle adjustment screws suddenly don't do much, the idle is too high. If that is the only way to make it run by itself, you still have a problem somewhere.
Thread Starter
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Mountain Pass
Joined: Jun 2007
Posts: 117
Likes: 6
From: Fort Worth TX
So I think I have the idle mixture screw about as good as they are going to get, but still doesn't run worth a darn. I tried to drive it around the block and I am much worse off than before I rebuilt carb. Essentially no power.
Could this be a problem with accelerator pump?
Could this be a problem with accelerator pump?