1987 R10 Silverado Oil Pressure Switch-Fuel Pump

[aos2771]

Hi,

I recently added a driver side 16 Gallon Tank to my Silverado pickup truck and It was right after i encountered a error on the road. My neighbor helped me bring back my truck with a Tie strap from Home Depot. The truck I had bought it from a used car dealer recently to. One day I smelled gasoline vapors around the driver side tank. I squatted down, look underneath and seen that it was leaking. Man, I was already worried, after looking everywhere i find that this issue is about the tank. It has this plastic piece that protects it from getting scraped if you drive over anything underneath. The black plastic piece was a bit handled with. Someone previously cut it and of course water is still going to get underneath it anyways but since it being this old the tank had rusted and it was where I found the leak. I replaced this from a nearby Auto parts store with 16 Gallon Tank. Then after 3 days later when trying to return home from washing my cloths at nearby washeteria only about 4 blocks down the road from it. The truck died on the road. When I got help bringing it back home. I began to diagnose it.
I discovered that the passenger side fuel pump was hooked up to the fuse panel with a 30A fuse to a splice on one of the wires of the fuel sending unit.
My neighbor helped in diagnosing it by adding fuel to the carborator and it turned on the motor only for seconds then it wouldn't stay running.
I called nearby Auto Parts and asked what could be causing it not to start?
They told me it could be many things, start by replacing the Fuel pump relay.
nothing. Then I read the shop manual and used some of their diagnosing procedures, using my multi-meter testing the wires from the Selector Valve, one of them tested 8 volts. I tested fuel pumps and got nothing from both of them. With my conclusion spectating the shop manual and its procedures, I replaced both fuel pumps with Spectre sending units , Selector Valve, and finally after replacing the last thing the Fuel Selector Switch, It started right up. However, I drove the truck around and it was running rich from what my nearby Muffler shop personnel told me. So I took it into a Mechanic Shop nearby with all the right equipment. They replaced the Computer and told me not to use the Passenger side gas tank. It is still behaving problematic though? It died on the road again? I read the shop manual and spectating it drawing no conclusions except a hunch that it could be the Oil Pressure Switch? When I press the fuel pedal I notice that the oil pressure gauge moves around but I don't have any idea if this is normal? Does someone understand any of this? Is it the Oil pressure switch, it doesn't cost much and if so maybe if i attempt to replace it is it that simple like chaning the Oil Filter? Will this prevent it from dying again? Furthermore, could there be an addition to its troubles perhaps changing one of the sensors? Does anyone have any drawings how the Selector valve hoses connections should be to the Sending units as well? Man this would be real help.