Vacuum problem

Swefury

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Kumla. Sweden
Hello!

I have a 73 Custom Suburban with a 2v 400 and I havea low flow of vacuum from the manifold to the brake booster. It is around 20 hg on idle but its a low amount of flow, The flow in the vacuum line from the carb to the pcv is much greater. When I pull the line to the brake booster on my 68 Fury the engine stumbles and dies but not on my 73. The problem I have is the vacuum to the booster is not enough but the booster is not leaking because it holds vacuum after I shut off the engine. It is a Imperial booster on it. Can I take vacuum from the carb to test to see if it works better?

TIA/Ola
 
As long as you are measuring.... does it improve considerably if you plug the pcv?? If so, try a new pcv.
 
Oxygenated fuels have caused some carbon problems. As noted pull the port fitting for the vacuum hose off the manifold to see if it is plugged. Be careful doing this as the small branch fitting is easily broken. Another possibility is that you might have a failing intake valve which will drop the manifold vacuum. A stuck EGR valve if so equipped will cause the same problem.

Dave
 
Oxygenated fuels have caused some carbon problems. As noted pull the port fitting for the vacuum hose off the manifold to see if it is plugged. Be careful doing this as the small branch fitting is easily broken. Another possibility is that you might have a failing intake valve which will drop the manifold vacuum. A stuck EGR valve if so equipped will cause the same problem.

Dave
The engine just has 60000 mile on it so I dont think it´s a valve it. I have removed the port fitting and it was not plugged.I have switched the hoses and there was no significant change. I will check the EGR valve tomorrow and maybe just make a cover to seal it off as we dont have to have it here in Sweden.
 
You never mentioned how well the engine is running. Does it run smoothly or rough, if smooth chances are the EGR is ok, but check it anyways. Does it run rough when you apply the brakes? Did you check the condition of the hose they do collapse inside and it doesn’t show from the outside. Are you sure the booster check balance is working.
 
You never mentioned how well the engine is running. Does it run smoothly or rough, if smooth chances are the EGR is ok, but check it anyways. Does it run rough when you apply the brakes? Did you check the condition of the hose they do collapse inside and it doesn’t show from the outside. Are you sure the booster check balance is working.

I think the EGR was stuck, after I moved it the brakes started to behave better. I gonna drive it for a while and see whats happening.
Thanks all for your help, I really apricated it.

Ola
 
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