Ok I have an 86 XLT Lariat 4x4 with a 302. It's an automatic. I have just completed getting my starting and charging system working, and now I'm on to the fuel intake system. From what I have seen I have an electronic fuel pump up underneath the driver door. There is the filter cartridge (black with 4 in/out adapters) and is bolted to the frame. Then there is an intake sending unit. I'm unsure what people are calling the High Pressure fuel pump. When we turn the ignition on I can hear the electronic pump priming or whining. I haven't heard anything in the tank. It wants to turn over and start, but I can't get it to completely crank. We now have the tank off and have the intank sending unit in a bucket filled with fuel. After turning the ignition to start I don't hear or see anything in the bucket where the intank pump is. I'm not sure what my next step is. If someone could please help me. I'm trying to find where the power comes from for the pumps. Do the 2 separate pumps run power from different sources? Does the electronic pump connect to the solenoid? I know there is a harness of some sort that that attaches to the intank sending unit but I don't know where it draws it's power from.

Thanks in advance for any help.

 

The tank pump is dead. The original-style (impeller) pump is VERY expensive, and is typically replaced with a MUCH more-affordable & common 3-9psi solenoid pump, available from anyone who sells auto parts.

The fuel pump power is:
1) the battery feeds the ig.sw., EEC, & FP relay via a fusible link wire near the EEC PWR relay.
2) when the key is in RUN or START, the EEC PWR relay comes on, and the EEC powers up & controls the FP relay.
3) when the EEC grounds the FP relay coil (~1sec after each key-on & any time the ignition system indicates the engine is spinning more than 150RPM), the relay sends power to the inertia switch.
4) if the inertia switch is set (not tripped), it sends power to the frame pump & the tank select switch on the dash.
5) the tank switch sends power to the selected tank pump.

So the fact that the frame pump runs says everything is good up to the inertia switch. If you put power directly to the pump in the bucket & it didn't run, it's definitely bad. If you were still using the tank wiring to power the pump in the bucket, you didn't really test anything, and it could be the pump, the tank switch, or the wiring.

I highly recommend buying the OLDEST Haynes you can find - preferrably red-cover. Read this caption:



For more info, read these:

 

Thanka for thw info and the link. Im going to check the inertia switch but the what im calling the eec relay (small green cap or box) neer the drivers side under the hood is making a popping noise when ignition is turned on. Also i only have one 16 gallon tank so would i have a pump selector switch as this link describes? I do have a selector switch below and left of my column but that seems to run to my winch. So i will test the sending unit and intake vavlve in thw filter catridge/reservoir and let you know what happens next.

Thanks again

 

I'm so used to people with 2 tanks having problems that I skimmed over where you mentioned 4 ports. Yours is a SFR, as described in the first few diagrams of that last link. Even though you don't have a tank switch, you have a jumper harness in the dash behind the panel next to the steering column, and those jumpers sometimes go bad. But you can pull the panel & test that harness for power. Whenever you hear the frame pump running, you should have power at the switch jumper harness.

As I said before, if there was a problem with the relays, you wouldn't hear the frame pump. But AFTER you get the current problem fixed, I highly recommend doing what this caption describes: