My father-in-law's stock '85 GS 5-spd seems to run fine when the choke is first engaged. Once it disengages, power drops dramatically. Uphill, can barely climb. Can't push throttle in to accelerate, can only lightly press throttle to get modest acceleration. Press any harder and engine bogs down. Reminds me of my Nissan sr20de motors when the throttle position sensor voltage is set incorrectly.

A few seasons back she was running rich and my FIL with a friend mechanic's help adjusted the idle mixture and some other stuff. All by, dead reckoning, LOL.

Other than this issue the motor sounds great, burns little oil. Gets stored every winter, can't believe the motor didn't lock up.

My FIL can't get in and out of the car anymore after neck surgery. I'm not sure if I want to take it on, but it does have sentimental value. My wife and I have share driving it over the last 20 years. And it's just fun enough to overcome having no air bags and a face mangling steering wheel.

Impressive little car, engine control system is something. Makes me miss ECU and diagnostic codes, LOL.

 

Forgot to mention it's a carbureted 12A. And a GS, not GL.

 

My guess is a vacuum leak.

 

Any guess as to where to best start looking?

 

The rats nest.

 

The symptoms in this TSB are almost exactly what happens when the warmup cycle is done.

 

The HAC is definitely bad. Not sure if it's the only issue but I'm having a block-off plate made tomorrow. Should know in the evening if it does the trick. My altitude is about 600 feet so no worries about running too rich.




Bad High Altitude Compensator.

 

Admins please change the topic to problem solved.

The HAC is bad, made a crude block-off plate to test. OMG does this car pull hard all the way to redline! Oh joy! Completely stock; all original, nothing removed but the HAC. The wife and I giggled the whole drive. Forgot to plug the hose back into the HAC during the test drive. Gotta figure out what to to with that bit.

Next up, windshield wipers are binding up and barely work, release bearing seems to squeal just a bit from time to time (or just do a clutch job), alignment and HVAC compressor since it's only ever been driven in the summer and me no likely the heat.



Block-off plate for high altitude compensator on the carb'd 12A.

 

thinking about checking that out with my first gen

 

I'm glad I came across this thread. I live in a city at 70m altitude and will likely never road trip this car to anywhere over 600ft. I should block off the HAC as well and remove the potential of this happening to my car....