PLEASE HELP!
Postmaster
Joined: Dec 2006
Posts: 3,603
Likes: 10
From: Spokane, WA
"...I have the Idle Mixture Screw ALL THE WAY IN!"
Something ain't right. Two important things: 1. Check for vacuum leaks 2. Make sure the float level in the carb is set correctly. Also, check the carb throttle plate shaft for loose. That can be a source of a hard to find vacuum leak.
Something ain't right. Two important things: 1. Check for vacuum leaks 2. Make sure the float level in the carb is set correctly. Also, check the carb throttle plate shaft for loose. That can be a source of a hard to find vacuum leak.
Tuned
Joined: Sep 2013
Posts: 453
Likes: 20
From: Little Rock, AR
"...I have the Idle Mixture Screw ALL THE WAY IN!"
Something ain't right. Two important things: 1. Check for vacuum leaks 2. Make sure the float level in the carb is set correctly. Also, check the carb throttle plate shaft for loose. That can be a source of a hard to find vacuum leak.
Something ain't right. Two important things: 1. Check for vacuum leaks 2. Make sure the float level in the carb is set correctly. Also, check the carb throttle plate shaft for loose. That can be a source of a hard to find vacuum leak.
Also I will try that with the float.
The throttle plate is tight, the springs are strong, I checked them yesterday when I rebuilt the carb.
Moderator
Joined: Dec 2007
Posts: 7,987
Likes: 104
From: Boise, Idaho
x2 on the vacuum leak / float. Being able to turn the idle mixture screw all the way in is a sure sign that something's not right. Generally a vacuum leak.
Carb cleaner works well, too, for checking for vacuum leaks. Get a good vacuum gauge too and put it on direct manifold vacuum. Sometimes it's much easier to see the needle wiggle than it is to listen for RPM changes or stumbles.
Carb cleaner works well, too, for checking for vacuum leaks. Get a good vacuum gauge too and put it on direct manifold vacuum. Sometimes it's much easier to see the needle wiggle than it is to listen for RPM changes or stumbles.
Tuned
Joined: Sep 2013
Posts: 453
Likes: 20
From: Little Rock, AR
x2 on the vacuum leak / float. Being able to turn the idle mixture screw all the way in is a sure sign that something's not right. Generally a vacuum leak.
Carb cleaner works well, too, for checking for vacuum leaks. Get a good vacuum gauge too and put it on direct manifold vacuum. Sometimes it's much easier to see the needle wiggle than it is to listen for RPM changes or stumbles.
Carb cleaner works well, too, for checking for vacuum leaks. Get a good vacuum gauge too and put it on direct manifold vacuum. Sometimes it's much easier to see the needle wiggle than it is to listen for RPM changes or stumbles.
I need to know about the pcv valve. I dont have the top one hooked up at the moment. Where should the top port be plugged into? It was just capped, but then when I open the oil fill hole it makes a sucking noise. It doesnt seem right.
Also: what does a good idle sound like on the motor?
Can someone put a video of theirs with the normal exhaust?
Moderator
Joined: Dec 2007
Posts: 7,987
Likes: 104
From: Boise, Idaho
I don't recall where the top port goes, but I think that's mainly for emissions stuff. The big, bottom port is the one that really needs to be hooked up. If the top one's not, it's not going to make too big of a deal. Probably something that opens it up under x amount of acceleration under y conditions, etc.
If you have the wiring diagram sticker on the radiator support up front, it may tell you what goes to it.
A good idle is consistent. It should be free of little pops, sucking noises, stumbles, etc. It should just be a smooth, mellow rumble.
If you have the wiring diagram sticker on the radiator support up front, it may tell you what goes to it.
A good idle is consistent. It should be free of little pops, sucking noises, stumbles, etc. It should just be a smooth, mellow rumble.
Tuned
Joined: Sep 2013
Posts: 453
Likes: 20
From: Little Rock, AR
That makes sense. This engine just sounds so much like a tractor, its hard to hear all the subtle things!
Thank ya tho. Yalls help has her running!
Just one thing. I will get her running good, but then Ill come back later and she will barely start and run. Then I drop her in gear and she stalls out on me.
ANy suggestions?
Thank ya tho. Yalls help has her running!
Just one thing. I will get her running good, but then Ill come back later and she will barely start and run. Then I drop her in gear and she stalls out on me.
ANy suggestions?
Elder User
Joined: Feb 2013
Posts: 608
Likes: 0
Nice looking truck!! You may have mentioned this and I missed it.....you have the IDLE SPEED screw adjusted (not mixture screw)? FYI, an engine speed is based on how much air is allowed to get into the combustion chamber. The accelerator pedal is connected to the throttle plate in the carb, it will regulate how much air enters. Any air that enters by way of leaks around the intake manifold, EGR is extra air. Seems like that may be the problem. Perhaps the linkage for the throttle isn't right.....its connected and keeps the plate open.
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Tuned
Joined: Sep 2013
Posts: 453
Likes: 20
From: Little Rock, AR
Well, I have the mixture screw closed now but the truck will run when I crank up the idle speed screw.
When does the mixture screw take over? I mean, its running really rich. Or I would say so judging by the black mark I left on the side of the neighbors apartment. Its like if the throttle plate is closed, she floods out. Even with the mix screw closed. And if the choke plate is closed, she does the same.
When does the mixture screw take over? I mean, its running really rich. Or I would say so judging by the black mark I left on the side of the neighbors apartment. Its like if the throttle plate is closed, she floods out. Even with the mix screw closed. And if the choke plate is closed, she does the same.
Postmaster
Joined: Dec 2006
Posts: 3,603
Likes: 10
From: Spokane, WA
"You can't tune out real problems"
X2 A properly functioning carb can be tuned but until the source of the problem is rectified no amount of tuning is going to correct it. Do you have access to a known good carb to try?
X2 A properly functioning carb can be tuned but until the source of the problem is rectified no amount of tuning is going to correct it. Do you have access to a known good carb to try?
Elder User
Joined: Apr 2012
Posts: 544
Likes: 6
From: Kalispell, MT
its tough to tell what an engine's symptoms add up to when the real issues are masking the tuning issues...agreeing with the other fellas here. having said that, an improperly set choke can cause starting issues and stumbles after start-up later on. might be something else to look into once you get those vacuum leaks sorted out.
p.s. the throttle plate and shaft are pretty common areas for air to slip past on carter carbs...yf or yfa.
p.s. the throttle plate and shaft are pretty common areas for air to slip past on carter carbs...yf or yfa.
Elder User
Joined: Feb 2008
Posts: 640
Likes: 1
From: US/Baja border
I agree! If it worked before it should work now. Keep it simple and don't get paralysis of analysis
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