Damn you cold weather

[Veraciousreasoning]

Hey All,

 

Been away for a couple days now dealing with work and the truck. The cold has brought a bunch of problems that I need help resolving. 

 

1. I seem now to have the dreaded "lifter tick". 

2. When I start the truck in the morning the RPMs are far below what the carb is set to. It pulses between 300-400 RPMs and shakes really bad for a good 10 minutes before it warms up to normal temperatures. 

3. When I am driving and stop at a red light the truck stays at 1,200 RPM's and I have to press the pedal gently to get it down to my normal idle speed of 700-900 rpms. 

 

Also, does anyone have experience or a video that shows me how to tune this carb? I have a 1980 720 

[datzenmike]

 

 

Next cold morning take the top off the air filter and look. The choke flap should be mostly open. Have someone step on the gas. The choke flap should snap completely closed. Does it?????

 

Part of the choke function is a fast idle. Spray the rear side of the carburetor with WD-40 and while holding the throttle half open, move the choke plate open and closed and any linkage that moves spray it clean. Cold start and run should be around 1,800 RPMs and slowly lowering as engine warms and choke opens..

[Veraciousreasoning]

2 hours ago, datzenmike said:

 

 

Next cold morning take the top off the air filter and look. The choke flap should be mostly open. Have someone step on the gas. The choke flap should snap completely closed. Does it?????

 

Part of the choke function is a fast idle. Spray the rear side of the carburetor with WD-40 and while holding the throttle half open, move the choke plate open and closed and any linkage that moves spray it clean. Cold start and run should be around 1,800 RPMs and slowly lowering as engine warms and choke opens..

 

I have done that previously and it closes completely when I press the gas pedal 1-3 times. 

 

IT never fast idles at 1,800 rpms. It usually fast idles at 1,000 rpms. 

[Veraciousreasoning]

11 hours ago, datzenmike said:

 

 

Next cold morning take the top off the air filter and look. The choke flap should be mostly open. Have someone step on the gas. The choke flap should snap completely closed. Does it?????

 

Part of the choke function is a fast idle. Spray the rear side of the carburetor with WD-40 and while holding the throttle half open, move the choke plate open and closed and any linkage that moves spray it clean. Cold start and run should be around 1,800 RPMs and slowly lowering as engine warms and choke opens..

 

 I am off this entire weekend and would love to try to resolve this before Monday if possible. Also, do you have any advice on the other things I brought up?

[datzenmike]

They may clear up when the choke is working properly.

[Veraciousreasoning]

5 minutes ago, datzenmike said:

They may clear up when the choke is working properly.

OK well the sun just came up enough for me to do what you said and I'll give you a report when I am done. 

[Veraciousreasoning]

18 hours ago, datzenmike said:

 

 

Next cold morning take the top off the air filter and look. The choke flap should be mostly open. Have someone step on the gas. The choke flap should snap completely closed. Does it?????

 

Part of the choke function is a fast idle. Spray the rear side of the carburetor with WD-40 and while holding the throttle half open, move the choke plate open and closed and any linkage that moves spray it clean. Cold start and run should be around 1,800 RPMs and slowly lowering as engine warms and choke opens..

 

OK so spent some time working on the problems.

 

-I had my girlfriend press the pedal 2-3 times and the butterfly snapped closed.

-I took the air filter off and cleaned the entire outside of the carb (with it off)

-Turned the engine on and sprayed it while moving the throttle with my hand

-Used wd-40 on the what I believe is the fast idle screw (the screw closest to the cab and has the throttle cable attached to it)

 

I waited about a hour to let it get cold again. Pressed the pedal 2-3 times and started it up. It went straight to 1,800 RPMs. However, as it warmed up the RPM did not change it just stayed at 1,800 RPMs.  Even when it got close to the 1/2 mark on the gauge it stayed at 1,800 RPMs. 

[datzenmike]

The fast idle cam simply gets in the way of the throttle closing. Once warmed up, about 10 min, the choke is off and the cam is free to drop out of the way but is held in position. Step on the gas pedal and the fast idle cam is released and should freely drop out of the way and the throttle is free to drop down to it's idle position.

[Veraciousreasoning]

4 minutes ago, datzenmike said:

The fast idle cam simply gets in the way of the throttle closing. Once warmed up, about 10 min, the choke is off and the cam is free to drop out of the way but is held in position. Step on the gas pedal and the fast idle cam is released and should freely drop out of the way and the throttle is free to drop down to it's idle position.

 

I let it warm up for about 10-15 minutes and hit the pedal and it didn't move from 1,800 RPMs. I just tried about 5 minutes ago since its much colder and its back to running at 800-1,000 RPMS. Can I increase the fast idle screw to increase the RPM? The manual I have about the carb is really confusing. 

[datzenmike]

 

 

This plastic thing is the fast idle cam. Hold the throttle part open and move the choke plate from open to closed and watch it move.

 

There could also be another reason the fast idle does not come off when it is warmed up but you have to eliminate the fast idle cam sticking first. Liberal spraying with WD-40 usually does the trick.

 

 

[Veraciousreasoning]

3 hours ago, datzenmike said:

 

 

This plastic thing is the fast idle cam. Hold the throttle part open and move the choke plate from open to closed and watch it move.

 

There could also be another reason the fast idle does not come off when it is warmed up but you have to eliminate the fast idle cam sticking first. Liberal spraying with WD-40 usually does the trick.

 

 

 

I'll look at it in the morning and get back to you. 

[Veraciousreasoning]

14 hours ago, datzenmike said:

 

 

This plastic thing is the fast idle cam. Hold the throttle part open and move the choke plate from open to closed and watch it move.

 

There could also be another reason the fast idle does not come off when it is warmed up but you have to eliminate the fast idle cam sticking first. Liberal spraying with WD-40 usually does the trick.

 

 

 

So this morning woke up and tried starting it. It didn't get to 1,800 RPMS from the fast idle. It went back to sputtering around 600-900 RPMs in a pulsing manner. I did what I usually do which is step on the pedal to get it to about 1,500-1,800 RPMs and let it sit for about 30 seconds. Once I release the pedal it idles around 700-900 RPMs. I am starting to wonder if the Carb is even set correctly. I did spray the fast idle cam down and the fast idle screw system with wd-40 and it did to seem to have a decent effect. 

How do I set the 80 carb? With the fast idle screw do I screw it in to make the fast idle go higher or out? With the other 2 screws how do I set it?