L-Jet going full Rich on Deceleration Options

[Brian Fuerbach]

1974 1.8 with L- jet. Been playing with a wide band air fuel meter and noticed that when I lift the throttle the AFR goes to max value on the gauge. I thought it was supposed to go lean. I checked the throttle position switch and it checks out fine. Going to check the wiring harness next.

What else should I check? Decel valve?

[r_towle]

My experience with this is two things.
1) a dirty distributor advance plate area. The OEM grease is now like hard gooey plastic, and it is no longer a lubricant, its more like glue now.
Remove dizzy, take it all apart and clean it, make sure the advance plates move freely and fast. Make sure they snap into the non advance position.
Add wheel bearing grease...about 0.05 cents worth. Car will be happy.
2) you have a vacuum line plugged into the wrong place, or the wrong way.
try nothing on vacuum advance (at the dizzy) then try nothing on the retard.
If I recall, you may end up with a hose on vacuum advance, and nothing at all on the retard, just leave it open to the air.
2a) a vacuum leak with make the car have a higher idle..so that too,

Overall, the car will run with all vacuum ports closed off at the plenum, then you can add one hose at a time until you find the culprit.
Dont trust that after almost 50 years that something is not leaking, has a hairline crack (plenum) or some fitting or hose is no longer perfectly tight.

EFI is all about measured air/fuel to get it right.
You have an air issue.

Rich