Chasing a stumble/roughness.

After replacing booster check valve for certainty, I should be able to pull & hold vacuum with a Mitty vac tool, correct?

Other than ruptured diaphragm, leaking perimeter seal, etc inside booster has leak, right?

Meaning its booster time.

Also, the charcoal canister purge valve.

It should hold vacuum in at least 1 direction (in un-powered state)?

Thanks, I could use some verification.

 

The charcoal canister should yes it has a check valve to hold the vacuum you would have to block the ports and vacuum down the check valve is like a flap basically lets it vacuum out but stops pressure I think right at the fitting. Not sure on the Booster but I would guess yeah it should hold some sort of a vacuum.

 

I tried checking line from purge valve back to canister through valve & no restrictions.

That's nipple-valve-line-canister. (all connected)

Pumping through just the valve from opposite direction, there is enough of a restriction that the gauge will at least lift its needle for a moment while actively pumping.

Pumping rapidly on the booster moves the needle not at all.

 

SOURCE- Classic Chevy, Chevrolet, GMC, Ford technical articles

 

Mitty vac alone will not pull enough vac to test booster.

Using another household pump, I pre-loaded booster & used the mitty to gauge & boost up, but got no hold.

Used same procedure to check replacement booster which held vac.

Wait till you get ready to rep a brake booster.

Choices are extremely limited.

Purge solenoids are very pricey & too much to rep on a whim & so the TB nipple is for now capped.

Since no one can tell me anything definitive (and I can't find anything) on the state of the solenoid (NO/NC, energized/non-energized, etc) I'll drag the mitty to the JY & do some tests.

Results are good, stumble/slight miss at 60-65 & 70-75 is gone.

 

The purge solenoid will hold vacuum going from the canister side and slowly drop vacuum in the engine side direction.
It blocks pressure both ways.


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Thank you.

Then mine is most certainly bad. I can only get a slight restriction in one direction

Is the valve closed in the un-powered state & constantly open while engine is running?

 

The above post and image is in the un-powered state.
My guess is the it would be open in both directions.
I would go back to the bench an check the powered state but I am running out of time right now and need to get going. Maybe I will check it out tonight.

 

Here 'Ya Go-

 

KULTULZ,
We do not use the vacuum operated purge valve in a 1994 F-series truck.

He has this one:


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... D'oh! ...