1989 F-150 4x4, 300, EFI. No fuel to fuel rail - Ford Forums

FirstFord89 · 06-23-2009, 12:19

Hi. My son and I were given a 1989 F-150 4x4 with a fuel injected 300ci straight six for him to fix for his 16th birthday. The truck sat for two years, and wasn't well maintained when operating. We've managed to correct no cranking and no spark. We're now stuck on no fuel to the fuel rail.

A colleage at work has an early '90s F-150 and you can hear the fuel pumps activate for a few seconds when the key is turned. My truck makes no sounds at all.

So far I've checked the actual fuel amount, and added new gas. I checked the Schraeder (sp?) fitting and no gas came out of it. I've cleaned all the obvious ground points, and checked the inertia switch (the button wasn't up, but I pushed on it just in case). I found and replaced the fuel pump relay. No change. I held the relay when the switch was turned, and couldn't feel any "bump" indicating the relay was engaging. I ran a direct ground to the battery with a test light and had my son turn the key. I had power to the sending unit at the tank pig-tail, but no power to any other line.

I'm not a mechanic, just a tinkerer and have the general hand tools. I did get a wiring diagram, but its somewhat less than helpful. What I really need is a Fuel Injection for Dummies kinda' thing. For example ground the tan/white wire on the relay end and see if the pumps start.. or jump the red and yellow wires at the relay end.. that should activate the pumps. If that works the fault is in the front of truck somewhere... that kinda' thing.

Its been a great father/son project..and its a cool truck. I'd like to be able to help him finish it and get it on the road... THANKS!!

**jwko** · 06-24-2009, 00:50

Have you checked the fuel filter?

FirstFord89 · 06-24-2009, 06:27

Replaced the old fuel filter due to its age and the truck sitting. Tried turning the key with the old filter removed. No gas came from the line.

thefonz · 06-24-2009, 10:13

FWIW, on some of the Fords, there is a small ground wire coming off the battery, if this looses connection, the fuel pump will not run even though the other ground is good. Also have you checked fusible links?

FirstFord89 · 06-24-2009, 14:10

I've not checked fusable links. I'm not sure where I'd actually check them. I could check the relay female end, but I don't know which and what connections are hot on closing and grounded on closing. There were two black wires that connected to the negative post that were broken. I reconnected them to the negative terminal. I didn't check the other end. I did directly ground the Fuel Pump Relay connector in the EEC. No change. No power to the fuel pumps. The truck will run if I spray starting fluid into the air intake. I"m sooo close, I'd hate to give up on this project.. Thanks!!!

FirstFord89 · 06-25-2009, 07:18

Let me be more clear about the EEC. I grounded connection 926 (Fuel Pump Relay Ground) on the EEC test block directly to the battery negative terminal and turned the key on.. still no power to the fuel pumps. I also checked to see if the two small black wires on the negative batter terminal were grounding.. they are. What direction now?? Thanks...

Steve83 · 07-05-2009, 11:42

'84-89 uses a low-pressure pump in each tank. Then a pressure-operated switching valve, a filter, & a hi-pressure pump all in the L frame rail under the driver's floor. The pump power comes from a relay under the L hood hinge, goes to the inertia switch under the dash, then splits to the hi pump & the dash switch. The switch sends power to the selected tank pump & also connects the corresponding level sender to the gauge.

The biggest problem (IME) is for the relays or their wiring to go bad, so I always recommend changing them to the later Bosch/ISO style, as shown in this & the NEXT few pics:

But if you'd rather not right now, the rest of this still applies. Install a jumper wire from ground to the FP relay terminal in the DLC as shown in the lowest pane of this diagram (ignore the top - it doesn't apply to your truck), turn the key to RUN, and check for 12V on the FP relay output wire:

Then crawl under the truck, & listen for the frame pump & the selected tank pump. If you have dual tanks, select the other tank at the dash switch & check it. If any isn't running, test for 12V to their power wires. If present, replace the non-functional pump(s). If not, test at the inertia switch.

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If the tank pumps ARE running but no fuel is flowing, unplug them while you disconnect their fuel lines, position a catch-pan, & then plug them back in momentarily to check flow. If there's no flow (or very little), you'll have to access the tanks to inspect & possibly replace the pump or tank. If there IS flow, click my black Bronco in my sig & read all the captions in the '84-89 Fuel Reservoir album.

thelittle289 · 07-11-2009, 21:41

also check the reset botton on the inertia switch. i should be pressed in. i had an 89 5.0 stang and every time i'd spin dougnuts, it would trip and i had to get out and rest it.