How important is the purge valve?
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Poor kid with a money pit
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From: Pittsburgh, PA
How important is the purge valve?
I recently got my FB and the PO did a rats nest removal. However, he did not connect up the purge valve and just ran a vac hose from the oil tube to the carb. How bad will this affect the performance of the vehicle? The vehicle is performing very poorly at the moment: will not idle at below 1200-1500rpm, hard to start, and surges at anywhere below 2000rpm. Could the missing valve be contributing to these symptoms?
I recently got my FB and the PO did a rats nest removal. However, he did not connect up the purge valve and just ran a vac hose from the oil tube to the carb. How bad will this affect the performance of the vehicle? The vehicle is performing very poorly at the moment: will not idle at below 1200-1500rpm, hard to start, and surges at anywhere below 2000rpm. Could the missing valve be contributing to these symptoms?
RXDad
Joined: Sep 2005
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From: Smiths Falls.(near Ottawa!.Mapquest IT!)
That valve,IF I am correct is a ONE way valve.
So really you got a Vacuum leak from the Carb to the Oil.It is sucking air into the carb where it should't be.
Doing what /\/\ says should cure it.
Put a one way valve or a PCV back on it,and it should straighten out the idle situation.
So really you got a Vacuum leak from the Carb to the Oil.It is sucking air into the carb where it should't be.
Doing what /\/\ says should cure it.
Put a one way valve or a PCV back on it,and it should straighten out the idle situation.
talking head
Joined: Apr 2008
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From: Perth, WA, OZ
PCV is NOT a one way valve,, it has a shape inside that makes it flow LESS at high vacuum ( idle ) and more at WOT
if you use a simple one way valve the motor will draw excessive idle air bypass down this vac line
if you use a simple one way valve the motor will draw excessive idle air bypass down this vac line
Joined: Aug 2010
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From: East Palestine, Oh
Just take the vac hose off and plug the port at the carb to see if it fixes it, if it does, then leave it capped and leave the oil fill tube port open. 
simple
simple
Thread Starter
Poor kid with a money pit
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From: Pittsburgh, PA
did not fix it. I'm going to fuel pressure test because I think the PO put an aftermarket fuel pump on... Then I will do vacuum test, anyone know how much vac pressure the 12a is supposed to have?
Worth checking out. It helps when people do something right, and don't leave a mess for others:
http://maz_tutorials.ten15.net/Tutorial_1.pdf
http://maz_tutorials.ten15.net/Tutorial_1.pdf
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Thread Starter
Poor kid with a money pit
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From: Pittsburgh, PA
Ok, I put the vacuum test on it today. It surging between 13-15 in Hg @ 1000-1100 rpm , is this normal/ good amount of vacuum? I couldn't get the tester on the fuel line, I need a line 'T'. I'm pretty sure 15 in Hg is sufficient vacuum so I'm thinking it might be fuel pressure.
Joined: Mar 2009
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From: Minneapolis, Minnesota
The surging under 2k rpm might also be due to the nature of the rats nest removal. Theres a shutter valve for the rear rotor on the primary port that shuts when you let off the gas to smooth out decel.
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MidnightOwl
2nd Generation Specific (1986-1992)
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Sep 25, 2015 10:24 PM
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