Monza idle/vacuum problem

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Monza idle/vacuum problem

Postby jaydawgnit1000 » Fri Oct 08, 2010 5:30 pm

hello h-body friends. Im having a issue with my 78 2+2 monza 3.2 litre. when i came home the other day i realized it wasnt idleing right. i waited till morning and started it up and it took longer then usual. when it did start the idleing was 1000 rpms and it would stall out on me. i lifted the hood and found that there was a vacuum hose missing or a cap. i stuck my finger to the hole and it would suck. if i left my finger there it would run better but 8 times out of 10 when i took my finger off it would stall out again. im not sure if it needs a cap on it or a hose. i looked everywhere and didnt find a loose hose. i didnt want to cap it just in case it gives me more future problems. it is located behind my carb and a little bit lower. here are some pics so you can get a better idea what i am talking about:
Image
Image
Image
these last 2 pictures are where the main hose leads to. it is the thicker one. im just moving the other ones out of the way for a better veiw. it looks to me its going streight to the top of the motor. Image
Image hopefully someone will know the exact problem i am having. thank you guys for looking this topic over and i appreciate all the help ahead of time!! :)
1978 Chevy Monza 2+2
3.2 litre v6
5 speed Manual

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1978 Chevrolet Monza 2+2


Re: Monza idle/vacuum problem

Postby cosvega76 » Fri Oct 08, 2010 5:51 pm

Jeff,

My guess is that is for the hose that goes to the ThermAc (vacuum-acutated flap in the air cleaner snout) system in the air cleaner.

Chuck
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Re: Monza idle/vacuum problem

Postby cjbiagi » Fri Oct 08, 2010 5:55 pm

That's a good possibility since obviously the air cleaner has been removed. If you use a aftermarket air cleaner that does not require that vacuum hose then just plug it. It's just a vacuum port, you are not going to hurt anything.
Clyde.........75 Monza 2+2
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Re: Monza idle/vacuum problem

Postby jaydawgnit1000 » Fri Oct 08, 2010 5:57 pm

Clyde: i do have the regular one on i just moved it for a better veiw.
1978 Chevy Monza 2+2
3.2 litre v6
5 speed Manual

Jeff Foley
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1978 Chevrolet Monza 2+2

Re: Monza idle/vacuum problem

Postby jaydawgnit1000 » Fri Oct 08, 2010 6:05 pm

I just went out and looked at the ThermAC and the hose goes to the inside of the cleaner and then another hose that is connected to the ThermAC in the cleaner goes right next to where the hole that im having the problem with.
1978 Chevy Monza 2+2
3.2 litre v6
5 speed Manual

Jeff Foley
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1978 Chevrolet Monza 2+2

Re: Monza idle/vacuum problem

Postby marco_1978_spyder » Fri Oct 08, 2010 9:30 pm

If your car has No AC, then a cap went there from the factory. GM # 3940920.
1978 Monza Spyder V8 4speed, posi
1978 Sunbird Formula V6, 5 Speed, Hatchback
1980 Sunbird Hatchback 4cyl, 4spd.
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Re: Monza idle/vacuum problem

Postby marco_1978_spyder » Fri Oct 08, 2010 10:03 pm

Here ya go.
I even custom enlarged the main drawing for viewability.

C41 = No Air Conditioning. Good luck..
You do not have the required permissions to view the files attached to this post.
1978 Monza Spyder V8 4speed, posi
1978 Sunbird Formula V6, 5 Speed, Hatchback
1980 Sunbird Hatchback 4cyl, 4spd.
2006 Chevrolet Aveo 5 speed Hatchback
Yes, you can refer to me as Mark
Please visit my blog... http://chevymonza.blogspot.com/ Follow if you like!
Featuring special guests; Carl Beraytor and Ray D'atore

My Red spyder now has a youtube channel please Like and Subscribe!!!
https://www.youtube.com/channel/UCOzzSR ... ISuing7KLA
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Re: Monza idle/vacuum problem

Postby jaydawgnit1000 » Fri Oct 08, 2010 10:12 pm

Awesome! now where can i get this cap online?
1978 Chevy Monza 2+2
3.2 litre v6
5 speed Manual

Jeff Foley
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Joined: Wed Sep 30, 2009 2:58 am
Location: Forest Dale, VT

1978 Chevrolet Monza 2+2

Re: Monza idle/vacuum problem

Postby marco_1978_spyder » Sat Oct 09, 2010 8:09 am

http://shop.oreillyauto.com/ProductList ... egory=4016

But I'd just go to the auto parts store and get an assortment pack of them since you don't know exactly which size ya need.
1978 Monza Spyder V8 4speed, posi
1978 Sunbird Formula V6, 5 Speed, Hatchback
1980 Sunbird Hatchback 4cyl, 4spd.
2006 Chevrolet Aveo 5 speed Hatchback
Yes, you can refer to me as Mark
Please visit my blog... http://chevymonza.blogspot.com/ Follow if you like!
Featuring special guests; Carl Beraytor and Ray D'atore

My Red spyder now has a youtube channel please Like and Subscribe!!!
https://www.youtube.com/channel/UCOzzSR ... ISuing7KLA
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Re: Monza idle/vacuum problem

Postby jaydawgnit1000 » Tue Oct 12, 2010 6:08 pm

well, i capped the peice off. it helped a little but it is still dieing down on me.. idk what it is. i do know that the choke doesnt work right on the carb. also i found out that the top of the carb got loose some how..? tightened the bolts back up but it is still having the same problem.. idk whats wrong with this thing.
1978 Chevy Monza 2+2
3.2 litre v6
5 speed Manual

Jeff Foley
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Posts: 22
Joined: Wed Sep 30, 2009 2:58 am
Location: Forest Dale, VT

1978 Chevrolet Monza 2+2


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