chengny
Full Access Member
- Joined
- Feb 22, 2012
- Posts
- 4,086
- Reaction score
- 1,023
- Location
- NH
- First Name
- Jerry
- Truck Year
- 1986
- Truck Model
- K3500
- Engine Size
- 350/5.7
TSB on late 86's with 87 tanks installed - might apply to your case:
Some late built 1986 C/K trucks may have been built with 1987 fuel tanks. The 1987 fuel tank contains a fuel baffle which can cause interference with the fuel sender float arm and not allow the fuel gage to read below 1/4 tank of fuel. If the truck is equipped with dual fuel tanks, this condition can occur in either tank. If this condition is encountered, the fuel tank must be replaced. The 1987 fuel tanks can be identified by removing the fuel tank and fuel tank sender and checking for the reservoir (plastic) which is attached to the bottom of the tank by two studs which are approximately 4" from the center of the fuel sender unit, See Figure No. 1. Refer to section 6C-Fuel System for fuel tank removal and reinstallation procedures.
Some late built 1986 C/K trucks may have been built with 1987 fuel tanks. The 1987 fuel tank contains a fuel baffle which can cause interference with the fuel sender float arm and not allow the fuel gage to read below 1/4 tank of fuel. If the truck is equipped with dual fuel tanks, this condition can occur in either tank. If this condition is encountered, the fuel tank must be replaced. The 1987 fuel tanks can be identified by removing the fuel tank and fuel tank sender and checking for the reservoir (plastic) which is attached to the bottom of the tank by two studs which are approximately 4" from the center of the fuel sender unit, See Figure No. 1. Refer to section 6C-Fuel System for fuel tank removal and reinstallation procedures.
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