L Jet vacuum leak pursuit '74 1.8, How does this work? Options

[nihil44]

I have bragged to my carburettored friends about how the '74 1.8 L Jet starts off the key even after a lay off of a month or so. Lately it has required two cranks to start. I suspected a vacuum leak as I pulled a plug and the pluf looks like the mixture is lean but the exhaust tips are black



I made a smoke maker based on this YouTube site

THE BEST SMOKE TESTER YOU CAN BUILD!! / THE MR. FUSION MINI BUILD - YouTube

Applied smoke into the intake system and this is what resulted.



Over the years I have read about ensuring the oil filler cap has a good O ring and cap seal otherwise unmeasured air will enter the intake system downstream from the Air Flow Meter and cause a disturbance in the A/F ratio determined by the ECU.

There is a factory hole in the oil filler cap as revealed by the smoke test. I have 2 filler caps and they both have the small hole.

How does this work if the L Jet intake system is supposed to be closed?

I was expecting the smoke test to reveal a vacuum leak in the intake boot or elsewhere and that would be the 'aha' moment. Not so lucky. However I would like to confirm that the intake system is vacuum leak free.

Would appreciate some explanation from the collective brain trust.

A word of caution: If doing a smoke test, perform it outside or in a well ventilated garage otherwise it will set off the smoke detectors. How would I know this?

David

[Van B]

Considering I have never heard and am not even sure how to pronounce what you just said, I think it’s safe to say I did not know that lol!

I think another matter to consider is that things do go wrong when not being driven. I would also recommend spending some time in the car and shake out the dust and corrosion that may have set in. Points, plugs, fuel, and so many other things can go bad just by sitting. Maybe by after a run through a tank of petrol, she’ll come back to life?

[wonkipop]

Considering I have never heard and am not even sure how to pronounce what you just said, I think it’s safe to say I did not know that lol!

I think another matter to consider is that things do go wrong when not being driven. I would also recommend spending some time in the car and shake out the dust and corrosion that may have set in. Points, plugs, fuel, and so many other things can go bad just by sitting. Maybe by after a run through a tank of petrol, she’ll come back to life?

furphy = red herring.

https://en.wikipedia.org/wiki/Furphy