Looks like I have a lot of vacuum in the crankcase. There is a simultaneous draw into the crankcase into each valve cover breather hose (one being PCV valve hose, the other is hose/pipe leading into the air cleaner.

1984 L69.

Likely intake gasket issue? Is there any other source of vacuum to the crankcase other than the two valve cover breathers listed above?

MPG has been only 12. Runs rich. I think. Always. Backfires into the exhaust when cold when let off the gas pedal.

 

Sounds like it's working more or less exactly like it's supposed to.

The PCV valve pulls a vacuum; the other hose going to the breather hooks to that little filter inside the air cleaner for the PCV make-up air. That other one may be blocked. Should have some suction on it where it plugs onto the air cleaner.

Most likely none of that is related to the other complaints.

 

So far good news. To clarify, for my sake, there is vacuum at both valve covers with PCV removed on one valve cover and the pipe removed from the other valve cover.

If that's good, I'll be pleased. At current condition, the carb can not pull air from the PCV side, and the air cleaner cannot pull air from the other side. There appears that much vacuum in the crankcase.

Then if can overlook that (I hope), I've got fuel collecting in at the end of the hose extending from the charcoal canister. This is the hose at the multi-hosed valve thing in front of the carb (has several hoses to it, i apologize for not taking time to research name of the valve, but you are at PC now and hoping for reply).

 

CANISTER CONTROL VALVE. Fuel is collecting in the lowest hose of that valve. Took the valve off the car and fuel poured out.

 

Did the following:
Have always had a high idle. Now drops to normal (with valve covers plugged).

 

Backstep!

You gotta be loving this sofa

I had not do exactly as said above. I still had a line connected from PVC to carb which I did not see. A branch in the Y in the fork in the road in the wasn't paying attention.

Certainly a good source of vacuum.

Perhaps now can focus on fuel at the CCV.

I'll do some more diagnostics in this heat and give an update. You may want to save your keyboard until then. Thanks much. Rich

 

OK. Yesterday I misdiagnosed vacuum in crankcase, thinking failed intake manifold gasket. However, missed one of the vac lines of the PCV plumbing.

Backtracked on that.

Running rich. Backfires when cold when lifting off throttle.

This morning found that the Canister Control Valve is not functioning. When off the car there is a direct flow between CCV 'manifold vacuum from PCV' port and both CCV 'canister tube' port and 'carb bowl tube' port. Therefore I believe (for the time being) that PCV vacuum was drawing air directly from the carb bowl via CCV. Would explain why the CCV fills with raw fuel.

 

I high adjusted float can cause fuel to be drawn into the CCV.Just something to consider.Could also be the float is sticking, allowing the fuel bowl to flood.

 

OK. Good to know. Now with new (used spare) CCV installed, with zero everything out and track mileage. In the interim can pop off couple vac lines and fingers crossed no more raw fuel at CCV. May know yet today.

Ordered a Mity Vac the other day. Don't have it yet. But sure would have been helpful this weekend.

 

Drove approx. 40 miles. No raw fuel collecting in the CCV. Excellent. Seemed to run very well. Tried an MPG test, but such low miles it's difficult to say whether actually got better, or the fuel expanded during the drive, taking less to top it off. Possibly both, as the math came out to 29 mpg. I'll be pleased if it was 20, instead of the 11.2 of the previous tank.