Matt69olds
Full Access Member
- Joined
- Jan 8, 2018
- Posts
- 2,451
- Reaction score
- 3,819
- Location
- Central Indiana
- First Name
- Matt
- Truck Year
- 81
- Truck Model
- GMC 1/2 ton
- Engine Size
- 455 Olds
What kind of fuel pump was installed? If your truck had A/C, the pump will have had one feed line from the tank, one outlet to the carb, and a return line going back to the tank. Non A/C truck usually have a single feed/return line.
The return line is designed to circulate a little fuel back to the tank to help keep the pump cool. With the A/C on, underhood temps can get pretty hot. The other benefit of the return line is bleeding off fuel pressure when you shut off the truck. The heat from the engine can boil the fuel in the lines, causing pressure to go high enough to push the needle off the seat in the carb, causing it to slightly flood. This creates hot restart issues. Have the return line provides a way to relive the pressure.
If the pump has 2 outlets, make sure the second line isn’t capped off. I have seen lots of people do that, thinking the live doesn’t do anything. With the return line capped off, fuel pressure will be much higher than normal.
The return line is designed to circulate a little fuel back to the tank to help keep the pump cool. With the A/C on, underhood temps can get pretty hot. The other benefit of the return line is bleeding off fuel pressure when you shut off the truck. The heat from the engine can boil the fuel in the lines, causing pressure to go high enough to push the needle off the seat in the carb, causing it to slightly flood. This creates hot restart issues. Have the return line provides a way to relive the pressure.
If the pump has 2 outlets, make sure the second line isn’t capped off. I have seen lots of people do that, thinking the live doesn’t do anything. With the return line capped off, fuel pressure will be much higher than normal.