I own a 1988 F150 that suddenly quit working. There is spark present. There is however no fuel being pumped to the injection system. I checked the inline fuel pump and found no power present at the pump. Injection of a 12 V power supply resulted in proper pump function. I metered and traced the appropriate wire up to and thru the Inertia Switch. I have metered from the fuel pump relay back thru the inertia switch and have determined that there is continuity. According to the electrical diagram that I have,there are 4 wires into this relay. Yellow that is always hot (Checked and is indeed hot), brown which carries power to the Intertia Switch and to the pump (Metered from relay back to pump), tan with a light green tracer which provides a complete circuit for the relay activation coil, and a red wire which comes from the EEC Power relay ,providing power to activate the relay coil. Power for the pump relay to be activated comes for the EEC power relay via the red wire. I have been unable to locate the EEC power relay.

Does anyone know WHERE to find this relay. It should be readily visible but I can not find it nor does any of my documentation indicate the location of this component.

 

Should be right next to the fuel pump relay.

 

In the power distribution box you have two relays that control EEC. Looking at the box from the driver's side, Relay #1 is the EEC relay. It is in the near right hand side of the box style relays. In position #12, the farthest away from #1 on the back left corner is the (diode) relay for the EEC. Either could be affecting your issue. On my truck in position #15 in the interior fuse panel also affects the EEC. I am not sure on an '88. It should be printed in the fuse panel cover. Hope this helps.

 

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Kethan, I don't know if this will help you or not. I had a 97 Taurus that stopped and wouldn't crank. After all kinds of electrical checks end dead ends, we dropped the tank and found the hot wire shorted out inside of the tank, got it repaired and it worked again.

Glad there were no sparks, and no boom.

John

 

There is indeed a relay that is next to the fuel pump relay............ this relay, however does not have any of the color coded wiring that my circuit diagram says should be there. The most important being the Red wire that should provide power to the coil of the Fuel pump relay.

I had suspected that this relay might be the EEC power relay..... the reference material that I purchased is woefully inadequate. I purchased a "Haynes Repair Manual" for this specific year and model and they seem to have overlooked a component location section. If there is a resource that can give me accurate wiring detail for the EEC Power relay on a 1988, F150, 351, Four wheel drive, Manual transmission truck I would appreciate that information or the name of the resource.

p.s. Thanks for the help.

 

i was just at checker auto parts and noticed they have Chilton repair manuals and they even had one for my (your) truck. on the outside of the manual it said full wiring and vacuum diagrams.

does the pump in the tank come on?

 

i dont think the power Comes from the EEC relay it does GO to the EEC relay too but it also goes to a bunch of other things like TAD and TAB solenoids and all the injectors.

does your red wire have power to it? how about with the key on? not sure if you need the key on or not.

my haynes manual also shows that the red wire turns to blue after a fuseable link at the EEC relay. (i think)

 

The tan and light green goes to the ecc to complete the circuit to ground to energize the fuel pump relay if the eec is not powering up this could cause the problem. Also short the fp test connector (bottom right connector on the ecc test plug) to ground with the key on the pump should run if it does then either the computer is not coiming up or you are missing a ground for the computer. Any way with this shorted you can trace the power and see who isn't gettting juice. The tan and green should be hot all the way to the ecc when the key is on the ecc just switches on ground when the truck is running

 

im not trying to advertise this other site by any means but for the price they charge for the information the offer it is worth every penny i spent. they offer detailed wire / vacuum diagrams and diognostic trouble codes as well as symptoms and all sorts of other information .i believe i even got the url from here .try it out and see its well worth it . http://www.alldata.com/

 

Chick emergency cut off switch driver side behind dash on firewall red botton

 

88 manual says eec relay is located next to air cleaner support bracket under plastic shield; relay is fed from 12 v at starter relay thru fuse link N (18 ga brown) to a yellow wire, then out of relay to a blue fusible link (20 ga) to a red wire. The coil is picked up by a white/light blue lead to ground from ignition switch. Hope this helps.

 

Guys, you have been great. I have traced the power flow to the eec power relay. The eec power relay does work. The pump relay is turned on by a ground signal that originates on pin 22 of the electronic control module. This signal is missing (grounding this pin DOES cause the pump to work).

I have tried to find the control module. In some of the reference material I have, there is an indication that this module is located in the cab, passenger side, under the dash. At this location there is the heater core and assocaited ducting. There doesn't seem to be space behind these items for the module. Before I spend several hours removing these items, I thought I would ask the experts here if that is indeed the location of the computer control module.

The specs are F150, 1988, 4 wheel drive, 351 ....

Thanks for the help!

Kethan

 

hmmm i always thought it was behind the drivers kick panel.

 

The ECM is behind the driver's side kick panel. You can see the big 60 pin connector coming in to it from the firewall side.

The ECM only engages the FP relay under the following circumstances:

1) For two seconds when the key is first turned from off to on
-or-
2) When it sees the PIP signal from the TFI module (engine is running, or at least cranking)

If you cycle the key from off to on, and do not hear the fuel pump run for two seconds, something is wrong with the FP driver or wiring to the PCM. If it does run for two seconds, but won't run any other time, there may be a problem getting PIP to the PCM. Even if you force the fuel pump to run, the engine will not run well, if at all, if the computer does not get PIP, because that is how it determines how often to fire the fuel injectors.