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Old 04-15-2018, 11:53 AM   #1
76er
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Need emissions help

Hello, have 1990 Silverado 1/2 ton, 2 wheei drive, 350 engine, extended cab.
Smog pump missing off this truck and won't pass inspection in my state, only requires safety inspection but if it came with pump has to have it on there. Willing to buy one but don't know if im missing what ever the pump connects to
so i've been searching everywhere for a diagram of the emmissions system for my truck with no luck, have found a couple that supposedly are for my truck but it shows it with the air injection pipes that screw into the heads like the 80s model trucks and these models didn't have those, even my Chilton manual doesn't show mine. Does anyone have a diagram or know what the pump attaches to? 1988 to 1993 are the same, 1994 and newer are different. Thanks for any help.
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Old 04-15-2018, 03:09 PM   #2
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Re: Need emissions help

This is from a 1993 fuel & emissions manual.
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Did you give the model, year, engine, fuel system type, and transmission information?
If it is modified from what came stock from the factory, let us know that too.

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Old 04-15-2018, 03:21 PM   #3
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Re: Need emissions help

I edited my post to only have one photo at a time because with some browsers this site messes up multiple photo posts.
These are from the 1993 Fuel & Emissions Manual.
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Old 04-15-2018, 03:32 PM   #4
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Re: Need emissions help

Another from the 1993 manual.
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If it is modified from what came stock from the factory, let us know that too.
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Old 04-15-2018, 06:12 PM   #5
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Re: Need emissions help

I don't understand this requirement. I have a Calif. truck and it never had an AIR pump. Calif. was typically the state that required equipment like AIR so I don't know why NC would need it. Do you have exhaust manifolds where someone put plugs in pipe holes or are they bare of those ports.
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Old 04-15-2018, 07:37 PM   #6
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Re: Need emissions help

Quote:
Originally Posted by Mr_Rich View Post
I don't understand this requirement. I have a Calif. truck and it never had an AIR pump. Calif. was typically the state that required equipment like AIR so I don't know why NC would need it. Do you have exhaust manifolds where someone put plugs in pipe holes or are they bare of those ports.
PA has similar emissions laws. For 1975-1995 model year vehicles under 9,000 gvw, all vehicles must have the same emissions equipment it came from the factory with.
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Old 04-15-2018, 08:01 PM   #7
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Re: Need emissions help

76r... Could you take a photo ( photos), of what that area of your engine looks like now?

EVERY truck after the '70's have an "air pump".. also called a smog pump.

Your right side exhaust manifold should have connections for the attached plumbing, and there is a small pigtail / vacuum hose that will connect.

Yellow - most of smog system.
Orange - sensor pigtail / vacuum hose.
Red arrow- Smog Pump.
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Old 04-15-2018, 09:01 PM   #8
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Re: Need emissions help

Quote:
Originally Posted by 95 S_Trucker View Post
PA has similar emissions laws. For 1975-1995 model year vehicles under 9,000 gvw, all vehicles must have the same emissions equipment it came from the factory with.
You may have misunderstood the point I was making. Calif. always had the strictest smog laws as a 50th state vs. everyone else that had 49-state vehicles everywhere else. Why would my Calif. truck not have AIR when an NC truck required it. Only difference might be that my truck originally came with a 305 and I later replaced it with a 350. Could that be it?
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Old 04-15-2018, 09:26 PM   #9
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Re: Need emissions help

Quote:
Originally Posted by Mr_Rich View Post
You may have misunderstood the point I was making. Calif. always had the strictest smog laws as a 50th state vs. everyone else that had 49-state vehicles everywhere else. Why would my Calif. truck not have AIR when an NC truck required it. Only difference might be that my truck originally came with a 305 and I later replaced it with a 350. Could that be it?
My brother in San Diego had a 305 in his 1990 Chevy 1500. Had a smog pump also. Possibly it was removed. BUT, notice this decal on my fan shroud.

" W/O A.I R.".... I am not sure what it meant. I assumed it meant A/C... maybe not. I can assume an off-road only truck did not require it by law?
BUT,....In this decal, the serpentine belt seems to bypass the A/C compressor, unless no smog, has the A/C located lower on the engine?

Hmmmm....
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Old 04-16-2018, 01:21 AM   #10
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Re: Need emissions help

Here's a pic when I replaced this 350 with my spare in 2012. These are the stock brackets for an '89 with the AC comp right at the top. AIR pump would be mounted on the space below had it been optioned that way so you can see the AIR pump is in the dashed area of the pic on the shroud that was posted.
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Old 04-16-2018, 05:56 AM   #11
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Re: Need emissions help

Quote:
Originally Posted by Mr_Rich View Post
You may have misunderstood the point I was making. Calif. always had the strictest smog laws as a 50th state vs. everyone else that had 49-state vehicles everywhere else. Why would my Calif. truck not have AIR when an NC truck required it. Only difference might be that my truck originally came with a 305 and I later replaced it with a 350. Could that be it?
It's not that NC specifically required the air pump. They just require all emissions devices to be intact. It's that the truck was being operated in NC. I can bet there are a lot more trucks in NC that came from the factory without air pumps than with.

Quote:
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My brother in San Diego had a 305 in his 1990 Chevy 1500. Had a smog pump also. Possibly it was removed. BUT, notice this decal on my fan shroud.

" W/O A.I R.".... I am not sure what it meant. I assumed it meant A/C... maybe not. I can assume an off-road only truck did not require it by law?
BUT,....In this decal, the serpentine belt seems to bypass the A/C compressor, unless no smog, has the A/C located lower on the engine?

Hmmmm....
A.I.R stands for air injection reaction. It's the air pump/smog pump. It's purpose is to put fresh air(with oxygen) into the exhaust to help burn unburned fuel.


Op, can you snap a pic of your emissions label and post it? It may be on the fan shroud by the rad support or the air cleaner
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Old 04-16-2018, 09:00 AM   #12
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Re: Need emissions help

If 76r could post a picture, showing the lower passenger area... Then we can see what is missing - needed. ( Is the smog mount bracket there?)
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Old 04-16-2018, 10:09 AM   #13
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Re: Need emissions help

Quote:
Originally Posted by mountie View Post
76r... Could you take a photo ( photos), of what that area of your engine looks like now?

EVERY truck after the '70's have an "air pump".. also called a smog pump.

Your right side exhaust manifold should have connections for the attached plumbing, and there is a small pigtail / vacuum hose that will connect.

Yellow - most of smog system.
Orange - sensor pigtail / vacuum hose.
Red arrow- Smog Pump.

There were more trucks made without air pumps than with. There is also a tube that goes around the back of the engine to supply fresh air to the left exhaust manifold.

Quote:
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If 76r could post a picture, showing the lower passenger area... Then we can see what is missing - needed. ( Is the smog mount bracket there?)
We need a pic of the emissions label, so we can determine if this is an item the truck had from the factory.




OP, It will look like this. It will have a vacuum diagram. It may be black.

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Old 04-16-2018, 12:09 PM   #14
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Re: Need emissions help

This raises a question in my mind; is there a code in the option list that indicates the requirement for an AIR pump and related hardware?
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Old 04-16-2018, 01:34 PM   #15
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Re: Need emissions help

Quote:
Originally Posted by Mr_Rich View Post
This raises a question in my mind; is there a code in the option list that indicates the requirement for an AIR pump and related hardware?
The dealer should know by the VIN number? If the emissions decal on the fan shroud is missing...... that decal will show it clearly.
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Old 04-16-2018, 02:39 PM   #16
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Re: Need emissions help

As a matter of fact I still have the original upper fan shroud off my truck. When my truck was still relatively new the 305 had a factory defect/ cracked engine block in the lifter valley. I checked the oil one day and there was chocolate jello under the oil filler cap. This was at 30K miles. So I take my truck to the dealer for warranty work and the dealer "mechanic" (I hesitate to use the term) said that they only authorized replacement of the short block and so they put the damaged heads on the new short block. This guy cross threaded some SAE bolts into metric threaded holes and other assorted nightmares along with breaking the upper fan shroud. I gave up with dealership mechanics at that point. I had problems with the work that was done and months later I went to the local Pontiac dealer and bought a 350 OTC and installed it into my truck at the curb outside my apt. at the time. Best thing I could do at the time. I know I got side-tracked here but ignore it if you will and refer to the pics I posted.
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Old 04-16-2018, 02:50 PM   #17
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Re: Need emissions help

Mr Rich...

If your crappy engine repair was at a GM dealership, then you have a warranty ( if your original warranty / extended warranty is in effect)....
If you return to any GM dealer due to their (GM) bad repairs, & they accept the truck - ( same complaint / second visit),..... Automatically, that repair is exempt from any time/ mileage limitations.
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Old 06-20-2018, 08:15 AM   #18
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Re: Need emissions help

Quote:
Originally Posted by Mr_Rich View Post
As a matter of fact I still have the original upper fan shroud off my truck. When my truck was still relatively new the 305 had a factory defect/ cracked engine block in the lifter valley. I checked the oil one day and there was chocolate jello under the oil filler cap. This was at 30K miles. So I take my truck to the dealer for warranty work and the dealer "mechanic" (I hesitate to use the term) said that they only authorized replacement of the short block and so they put the damaged heads on the new short block. This guy cross threaded some SAE bolts into metric threaded holes and other assorted nightmares along with breaking the upper fan shroud. I gave up with dealership mechanics at that point. I had problems with the work that was done and months later I went to the local Pontiac dealer and bought a 350 OTC and installed it into my truck at the curb outside my apt. at the time. Best thing I could do at the time. I know I got side-tracked here but ignore it if you will and refer to the pics I posted.

I know this is a couple of months old, but that pic of your emissions label shows that your truck came from the factory without the air pump. It's not required to pass emissions.
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Old 06-20-2018, 11:53 AM   #19
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Re: Need emissions help

Quote:
Originally Posted by 95 S_Trucker View Post
I know this is a couple of months old, but that pic of your emissions label shows that your truck came from the factory without the air pump. It's not required to pass emissions.
Pretty sure he knows that

Quote:
Originally Posted by Mr_Rich View Post
I don't understand this requirement. I have a Calif. truck and it never had an AIR pump.
Quote:
Originally Posted by mountie View Post
Mr Rich...

If your crappy engine repair was at a GM dealership, then you have a warranty ( if your original warranty / extended warranty is in effect)....
If you return to any GM dealer due to their (GM) bad repairs, & they accept the truck - ( same complaint / second visit),..... Automatically, that repair is exempt from any time/ mileage limitations.
No it does NOT. What makes you think that? Warranty repairs are only in effect as long as the original warranty period. Lets say you get warranty repair that is on 6 years/ 50000 miles. Your vehicle is at 4 years / 48000 miles at the time of the repair. After 50000 miles or 6 years, which ever comes first. There is no more warranty.

It's also pretty obvious that he didn't care to answer back in April so chances are good he's done with this thread.
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Old 06-20-2018, 05:45 PM   #20
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Re: Need emissions help

Quote:
Originally Posted by speedygonzales View Post
Pretty sure he knows that





No it does NOT. What makes you think that? Warranty repairs are only in effect as long as the original warranty period. Lets say you get warranty repair that is on 6 years/ 50000 miles. Your vehicle is at 4 years / 48000 miles at the time of the repair. After 50000 miles or 6 years, which ever comes first. There is no more warranty.

It's also pretty obvious that he didn't care to answer back in April so chances are good he's done with this thread.
Speedy.... I think I still have my original warranty paperwork. It reads that if warranty work failed to resolve the 'customer complaint', and you return to dealer with a continued same complaint, AND THEY ACCEPT the truck for the second attempt, " No warranty limit due to mileage and date of repair at a dealer until repair completed". ( Written from Lemon Law)... Give me a few days.... I'll look for it.

Back in 1990, I had some serious warranty issues & spoke to GM in Michigan & wrangled the jerk-off "GM Rep" in So Cal.
( It had to do mainly with my defective transmission among other defects)
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Old 06-20-2018, 09:50 PM   #21
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Re: Need emissions help

We probably lost the OP with all of our back-and-forth comments. And I still don't trust dealerships unless I work there and I'm not hired at any and so it goes. My old truck has almost 289K miles with just me as the mechanic for the last twenty-five or so years. I've replaced/ repaired everything in the drivetrain during that time. It doesn't look pretty but I still like that old truck; gray primer and all. The interior is in clean and very good condition. Amazing what a upholstery cleaning machine can do to freshen things up.
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