Vacuum line issues on my 305 C10

[IamBigHog]

I'm having trouble putting my vacuum lines back on the air cleaner assembly. In the picture the vacuum line that's unplugged is the problem and when I connect the hose on to the assembly then it kills the engine. Could it be a bad PCV valve or something else?

 

[ali_c20]

Welcome from Austria.
Post more Information about the 305. California emissions? Federal? None? Carb? Tbi? Stock? Modified?
Get a Vacuum diagram for your truck and trace the disconnected line. It looks like it goes into the T on the pic and from there it goes to ?.

 

[IamBigHog]

It's a stock quadrajet w/ CARB emissions rules.
I found a small crack in a fuel line hose which I think might be it but I'd like someone's opinion on that.

 

[ali_c20]

Check all fuel hoses, if one is cracked others could be to.
Fix it and test what happens when you reattach the vacuum hose.

 

[75gmck25]

Take a picture from further out that shows where all those lines go, and to what device. Also get a picture of your emissions sticker and hose routing diagram.

 

[IamBigHog]

I'm probably gonna look for some vacuum leaks on the problem hose on the air cleaner. What's the best way to find vacuum leaks?

 

[75gmck25]

One way to find leaks is to get a can of starting fluid and carefully spray it where you think there might be a leak. The vacuum leak will usually suck in the fluid and the engine speed will go up.

One of the black lines in your diagram is the one coming from manifold vacuum, and I would start there with my checking. Put a vacuum gauge on vacuum source and see what you get at idle.

I have also read of guys also using a propane torch with no flame for the same troubleshooting, but it sounds a little more risky.

 

[Waylon]

Could it be that your carb was adjusted to run while the vacuum hose wasn't attached and when you plug it in, it changes the idle mixture enough to make it die?

 

[IamBigHog]

Could it be that your carb was adjusted to run while the vacuum hose wasn't attached and when you plug it in, it changes the idle mixture enough to make it die?

I adjusted the idle but when it was about to stall I adjusted the idle back to a higher idle and it still wanted to die. This engine always sounded like it idled high

 

[Ricko1966]

I adjusted the idle but when it was about to stall I adjusted the idle back to a higher idle and it still wanted to die. This engine always sounded like it idled high

How did adjust the idle,step by step.

 

[IamBigHog]

One way to find leaks is to get a can of starting fluid and carefully spray it where you think there might be a leak. The vacuum leak will usually suck in the fluid and the engine speed will go up.

One of the black lines in your diagram is the one coming from manifold vacuum, and I would start there with my checking. Put a vacuum gauge on vacuum source and see what you get at idle.

I have also read of guys also using a propane torch with no flame for the same troubleshooting, but it sounds a little more risky.

How did adjust the idle,step by step.

The idle screw is a nut and I turned by each side till sounded a little lower, I think I did two or three turns.

 

[IamBigHog]

I actually figured out the issue and its a rookie mistake, I mixed up two vacuum lines so I switched them around using an old photo I took before I took the air cleaner off 2 weeks ago, but thanks for the feedback

 

[Ricko1966]

The idle screw is a nut and I turned by each side till sounded a little lower, I think I did two or three turns.

That's not the proper way to adjust idle. Glad you found your problem though. You adjust idle mixture with the 2 screws at the base in the front of the carburetor. After mixture is set correctly then you set final speed with the throttle stop screw. You can create drivabilty problems just using the throttle stop screw to set idle speed. But glad you found your problem have a great evening.

 

[75gmck25]

Remember that the original idle screws have a double-d head, so you need a tool designed to fit that head. The tool is not expensive, but its only useful for turning idle screws.

When I ordered a rebuild kit from Cliff Ruggles it came with new idle screws that can be turned with a flat tip screwdriver. Much simpler.

Is it also possible that you have mixed up the ported cs manifold vacum ports on your carburetor? The original setup probably used ported (no vacuum advance at idle), and if you have it on manifold instead you would get vacuum advance at idle, which raises idle speed.

 

[IamBigHog]

Remember that the original idle screws have a double-d head, so you need a tool designed to fit that head. The tool is not expensive, but its only useful for turning idle screws.

When I ordered a rebuild kit from Cliff Ruggles it came with new idle screws that can be turned with a flat tip screwdriver. Much simpler.

Is it also possible that you have mixed up the ported cs manifold vacum ports on your carburetor? The original setup probably used ported (no vacuum advance at idle), and if you have it on manifold instead you would get vacuum advance at idle, which raises idle speed.

That I'm not too sure the screw I turned was the high speed idle if you were standing on driver side where throttle assembly was then it was right behind the idle stop solenoid and there's a factory bracket on the carb that makes it almost impossible to get a Phillips screwdriver on there.