Low87
Registered Member
No wiring. Two hoses in, one larger hose out.
CK5
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where is the ecm b fuse?
- Thread starter Low87
- Start date
New to me! 
I'll have to keep this in mind when I start dealing with the '87 then!
I'll have to keep this in mind when I start dealing with the '87 then!
Older post, but I just ran across this setup in the 1991 service manual.
Apparently "altitude" trucks used the setup with the valve on the vent line as shown in this thread. The Evap canister should have an extra, similar valve on top of it as well (integral) that was also only used on altitude trucks. A non-altitude truck of that vintage would not have either valve, and the Evap canister should only have two hose fittings.
New to me, but makes sense now.
Apparently "altitude" trucks used the setup with the valve on the vent line as shown in this thread. The Evap canister should have an extra, similar valve on top of it as well (integral) that was also only used on altitude trucks. A non-altitude truck of that vintage would not have either valve, and the Evap canister should only have two hose fittings.
New to me, but makes sense now.
Low87
Registered Member
That's interesting info. My truck came from the mountains of Arkansas. On level ground now in Okla. I wonder if it makes any difference having that setup at lower altitudes.
Not ECM controlled, so I doubt it.
I got a chance to look at my '87 tonight, and indeed it has the two hose Evap canister, which is reflected on the core support sticker.
I am surprised there are that many of the "altitude" trucks out there, to be honest. I have never seen a GM description of what that entailed, and if it's a federal designation based on delivery destination, or something GM used on their own.
I got a chance to look at my '87 tonight, and indeed it has the two hose Evap canister, which is reflected on the core support sticker.
I am surprised there are that many of the "altitude" trucks out there, to be honest. I have never seen a GM description of what that entailed, and if it's a federal designation based on delivery destination, or something GM used on their own.
