help needed, no vacuum
Thread Starter
Advanced
Joined: Jul 2010
Posts: 80
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From: Murcia - Spain
help needed, no vacuum
Hello folks;
I am testing the vacuum hoses from the intake and I have discovered that the vacuum hose to the charcoal cannister valve has not depression when the car is at idle.
Is it normal? When the cannister valve must open itself?
I have test the hose connection to the mainfold and it seems ok.
Thanks
I am testing the vacuum hoses from the intake and I have discovered that the vacuum hose to the charcoal cannister valve has not depression when the car is at idle.
Is it normal? When the cannister valve must open itself?
I have test the hose connection to the mainfold and it seems ok.
Thanks
Burning Brakes
Joined: May 2005
Posts: 1,007
Likes: 10
From: Chilton Wisconsin
What year car?
I think that the canister vaccum may not be active at idle, to much tendency to pull fuel vapor with limited air. I think the post in the throttle body is above the throttle plate so see if you get vacuum when you open the throttle slightly (do not over rev).
I think that the canister vaccum may not be active at idle, to much tendency to pull fuel vapor with limited air. I think the post in the throttle body is above the throttle plate so see if you get vacuum when you open the throttle slightly (do not over rev).
Thread Starter
Advanced
Joined: Jul 2010
Posts: 80
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From: Murcia - Spain
Thanks Roger.
It is a 89 AT. It has 2 valves the above shown (vacuum activated) and other near of oil filler neck with electric connection. I suposse that the last one is for open the hose only when the engine needs.
Thanks
It is a 89 AT. It has 2 valves the above shown (vacuum activated) and other near of oil filler neck with electric connection. I suposse that the last one is for open the hose only when the engine needs.
Thanks
Rennlist Member
Joined: Jul 2008
Posts: 2,288
Likes: 97
From: NW Arkansas
The metal topped valve in the photo is the air injection blow off valve. It controls the flow of air from the air pump, either sending it into the exhaust stream or dumping it into the intake air stream via the air filter. The black plastic valve is one of two that controls fuel vapor flow from the charcoal canister to the intake. Neither one should get a vacuum signal at idle.
Mike
Mike
Thread Starter
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Joined: Jul 2010
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From: Murcia - Spain
The metal topped valve in the photo is the air injection blow off valve. It controls the flow of air from the air pump, either sending it into the exhaust stream or dumping it into the intake air stream via the air filter. The black plastic valve is one of two that controls fuel vapor flow from the charcoal canister to the intake. Neither one should get a vacuum signal at idle.
Mike
Mike
I refer at the plastic valve. The black hose at its side is the vacuum hose from intake. It come directly from the plug above the throttle plate (there are two plugs, one for 5 port fuel regulator, dumper, AT, and the other is what we spoken).
I supose that this hose must have vacuum ......but I do not know when.
Thanks
Rennlist Member
Joined: Jul 2008
Posts: 2,288
Likes: 97
From: NW Arkansas
Since the vacuum line to the valve in question is connected above the throttle plate it will not see any vacuum at idle or wide open throttle, only at part throttle. As the edge of the throttle plate opens past the vacuum port for this hose the vacuum will be highest and will slowly decrease the farther the throttle is open until at some point before wide open all vacuum will be gone. The LH ecu controls the solenoid valve between this vacuum valve and the manifold. It sends pulsed signal depending on engine temperature, load, etc. to meter the fuel vapors from the charcoal canister back into the intake and not upset mixture and drive-ability. Hope this helps.
Mike
Mike
