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tucsonjwt · 11-12-2015, 06:23 PM

3/4 trucks were considered heavy duty for emissions purposes and had a short hose off the third nipple with a one way vent cap - same as the vent cap on the differential vent. On my 83 C20, I ran the vent lines back to the rear bumper area so I would not smell gas vapors in the cab. 1/2 tons all had charcoal canisters, as far as I know.

11-12-2015, 06:23 PM	#6
tucsonjwt Registered User Join Date: Jul 2007 Location: Tucson, AZ Posts: 3,198	Re: Fuel sending unit questions 3/4 trucks were considered heavy duty for emissions purposes and had a short hose off the third nipple with a one way vent cap - same as the vent cap on the differential vent. On my 83 C20, I ran the vent lines back to the rear bumper area so I would not smell gas vapors in the cab. 1/2 tons all had charcoal canisters, as far as I know.