Topic: No power in gear
in Forum: C3 Engines
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I have a 77 that returned to the road today for the first time in 6 years. When she is in park or neutral she revs fine but when she is in gear and is stomped on she does on move very fast and backfires. there is all new plugs and wires just put on last week. any suggestions?
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bad auto tranny modulator. It's operated by vacuum from the manifold and if it is not working you may just be drawing air through it and leaning off your intake mixture causing backfires etc.
However, I may be wrong.....
Sure sounds like a clogged catalytic converter to me. Had a Buick do like that and the shop dude cut a hole in the pipe just ahead of the converter and drove the car, the car ran fine, proving the converter needed changed.
I am having trouble finding the vaccum modulator at ecklers do anyone know where to find it?
Thanks
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I don't think the modulator is gonna be the problem. IF the modulator is bad, it will suck tranny fluid up the line into the intake, and you'll see some smoke from the tailpipes. Unless yer trans is completely empty of fluid, it's not adding any excess air into the intake.(unless, of course, the line is un-hooked..) 
I'd be looking into a carb issue...has the carb been cleaned/rebuilt after sitting for 6 years? How about the coil? It could do the same thing, too.
If you drive it easy, does it run ok? A clogged cat. converter will definitely cause it to run sloppy under heavy throttle, usually worse the more throttle you give it.
I'd be looking into a carb issue...has the carb been cleaned/rebuilt after sitting for 6 years? How about the coil? It could do the same thing, too.
If you drive it easy, does it run ok? A clogged cat. converter will definitely cause it to run sloppy under heavy throttle, usually worse the more throttle you give it.
Joel Adams
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Had an idling problem once. Idled fine in park, but when I put in drive the car would go dead. Plugged the vacuum line to the EGR valve worked fine. Know it's not exactly the same symptoms. Just might be something you would want to try.
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Sounds like it could be a firing issue. Sounds like the timing is off or possibly a couple of spark plug wires out of order. I would double check the spark plug wires since they were recently changed. Check the vacuum line to the distributor. Has the timing change ever been changed?
Is there excessive dark smoke out the exhaust when under load? That would point toward a possible fuel issue. Good luck trouble shooting!
Steve
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Thanks for all of the input guys,
With the expection for a new rotor button, wires and plugs everything with the engine is the same as it was 6 years ago. alot of people have been telling me that it is a carb issue. I have put some carb cleaner into the carb and the rest of the can in the tank. I have put 100 miles on her so far and she seems to be getting better. the cat conveters were off before I got her.
will let you guys know of the progress.
in Forum: C3 Engines
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