1988 F150 5.0 two tanks three pumps Two in tank pumps one high pressure on the frame rail. It has 2 relays Fuel pump relay and a ecc power relay . the fuel pump relay is not getting a ground from the eec. ( Where is located and how would you check see if it is bad?) I can jump the relay out and the pressure pump will come on but not the tank pump. with it jumped out the FT selector switch show to be changing checked with test light. This truck has been setting up for a few years but I drove it to this location and it has set here for a few years. I am fixing to pull the tank and clean it out put one pump in front set the selector switch to front and plug off the back line. I need know how to check the eec and the location. Thanks for any help

 

Most of the time the relays were located under the cowl against the firewall on the passenger side.
When the ignition switch is turned on, the EEC power relay is energized, closing it's contacts. Power is then provided to both the fuel pump relay and the ECA. The fuel pump then gets its power through the contacts of the fuel pump relay and the inertia switch. If the ign sw is not turned to the start position within1-2 seconds, the ECA will open the F/P relay ground. This turns off the fuel pump. After the engine is started power to the fuel pump comes from the F/P relay under the control of the ECA. This requires an RPM signal which if lost for any reason, the F/P relay will open preventing fuel from being pumped.
Connections checked as close as possible to the tank/pump unit, are the better way to check. Sometimes a rap under the inoperative fuel pump in the tank may get it going again although the engine should be cranking at the time. This , if it works, will work only a few times since the pump motor is on borrowed time. It seems they always crapped out right after a tank fill up.