fiatplus
Junior Member
- Joined
- Aug 2, 2023
- Posts
- 3
- Reaction score
- 4
- Location
- cali
- First Name
- chris
- Truck Year
- 1975
- Truck Model
- c10
- Engine Size
- 454
I own a 1975, the insurance company says it's a C10. Dual side tanks. As it sits a lot, I have had reoccurring rust in the fuel system issues for 35 years...
It recently started leaking fuel at the gas station when filling the tanks, so I concluded the rust had come thru the top of the tanks. Ordered new tanks, painted and sealed them, made sure the right tank was as empty as possible, then pulled the right tank.
The only rust thru was from the straps trapping moisture. And it was surprisingly clean inside. But I did discover the plastic "vent" on the center hard line of the tank sender was just an open hose, so I found my leak. Fuel lines 48 years old and showing it, so as I was tracing where the right tank hose attached to the tank solenoid, the plastic nipple fell off.
I got a new solenoid, and it's a five wire six terminal one. The old one was a one wire. I traced all of the wiring, and using the original three wires I installed the new solenoid. I then drained the left tank, replaced it and the hoses (discovered the same "open" vent on the middle sending unit nipple), connected everything, and the solenoid refused to swap between tanks.
I discovered voltage drops under load of five and eight volts from the new switch in the front and the solenoid harness, so I replaced all three wires. Now the solenoid swaps between tanks!
But, the fuel gauge now reads above full at the 3 oclock position. Swap tanks from an almost full one to an empty one and it moves, but not much. Ran grounds, jumper wires, tested continuity. Everything says the gauge should work, but it refuses to move back to where it has always been before I swapped all this tank stuff.
As I consider the fuel gauge as the most important gauge in the truck, what do I do next?
I am fresh out of ideas...
It recently started leaking fuel at the gas station when filling the tanks, so I concluded the rust had come thru the top of the tanks. Ordered new tanks, painted and sealed them, made sure the right tank was as empty as possible, then pulled the right tank.
The only rust thru was from the straps trapping moisture. And it was surprisingly clean inside. But I did discover the plastic "vent" on the center hard line of the tank sender was just an open hose, so I found my leak. Fuel lines 48 years old and showing it, so as I was tracing where the right tank hose attached to the tank solenoid, the plastic nipple fell off.
I got a new solenoid, and it's a five wire six terminal one. The old one was a one wire. I traced all of the wiring, and using the original three wires I installed the new solenoid. I then drained the left tank, replaced it and the hoses (discovered the same "open" vent on the middle sending unit nipple), connected everything, and the solenoid refused to swap between tanks.
I discovered voltage drops under load of five and eight volts from the new switch in the front and the solenoid harness, so I replaced all three wires. Now the solenoid swaps between tanks!
But, the fuel gauge now reads above full at the 3 oclock position. Swap tanks from an almost full one to an empty one and it moves, but not much. Ran grounds, jumper wires, tested continuity. Everything says the gauge should work, but it refuses to move back to where it has always been before I swapped all this tank stuff.
As I consider the fuel gauge as the most important gauge in the truck, what do I do next?
I am fresh out of ideas...
