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So I have a wire under my hood of my 86 efi 150 an I’m trying to figure what it powers due to it having 12v with key on 12v . This wire has a white wire on one side of this molex connector and the othe side of the connector is black the wire wire is coming from the harness the is near the power steering pump. Thanks for any help not to go off topic but idk if this wire controls the rear in tank fuel pump? The truck will only get 20 psi of fuel at the rail and will not rev that great, this issue is the last major issue I have before I can drive it
I would think almost any auto parts store can get you a condenser.
As for low fuel pressure, have you checked to see if you can hear the high pressure fuel pump prime, when you turn the key to On for a few seconds, before turning the key to start ? I don't drive my 86 much, but, I always turn the Key to On first and listen for the pump to prime.
Thanks so much for that pic, saved me a bunch of time. And yes the hp pump does prime when you turn the key idk about the filter but that was my next step. Will I need those removal tools to change the filter? Thanks again!
Thanks so much for that pic, saved me a bunch of time. And yes the hp pump does prime when you turn the key idk about the filter but that was my next step. Will I need those removal tools to change the filter? Thanks again!
No. That nonsense didn’t start until ‘92. Your truck should have the plastic “U” shaped retaining clips that you remove then disconnect the line.
I do not know what it holds but I can check that tonight after work, does the pump in the tank and the high pressure pump need to work together to create 45psi? Or can the hp do it all? Just curious because I remember the hp being louder when I used this truck every day I’m hoping it’s not on its way out.. I did replace it once years ago
They do work together but ...
The in tank pump is a low psi pump and is used to "lift" fuel to the high psi pump as the high psi pump, any electric pump, dose not pull fuel vary good.
So the low (lift) pump pushes fuel to the high psi pump and the high psi pump builds fuel to the 45 psi.
I dont even know if the high psi pump could pull fuel from the tank from where it is mounted, should be as close to the tank as it can and the inlet wet (below the fuel level) and would need to pull it thru the in tank pump too.
Dave ----
I did about 10 minutes ago ordered a new hp pump along with a new filter just to have on hand , I am really trying to get this truck moving down the road so a couple parts here and there I don’t mind . Once this fuel issue is fixed everything mechanical should be done besides a new exhaust.
They do work together but ...
The in tank pump is a low psi pump and is used to "lift" fuel to the high psi pump as the high psi pump, any electric pump, dose not pull fuel vary good.
So the low (lift) pump pushes fuel to the high psi pump and the high psi pump builds fuel to the 45 psi.
I dont even know if the high psi pump could pull fuel from the tank from where it is mounted, should be as close to the tank as it can and the inlet wet (below the fuel level) and would need to pull it thru the in tank pump too.
Dave ----
The high pressure pump probably could pull the fuel from the tank but not good. That is why there is a reservoir for the high pressure pump to be able to draw from.
The main reason for this complicated system is the tank has no baffle in it, no fuel cartridge in it. So the lift pump in the tank can starve for fuel, and then get fuel and then starve again as you go around turns and hit the brakes and accelerate. Think of the fuel reservoir like a fuel bowl in a carb. It's a reserve or storage system so the high pressure pump has a constant fuel supply, the lift pump in the tank puts fuel into the reservoir whenever it can, and returns the excess back to the tank. The high pressure pump returns to the reservoir, also supplying the reservoir fuel, more at idle, less at higher engine demands. So the reservoir is the key to the system, giving the high pressure pump a constant supply of fuel.
