FML

OK so i couldnt figure out what was wrong with my truck, it just wouldnt start, so i figured spark, i bought new plugs, wires, distributor cap, and router. turns out that did nothing, so then i put starter fluid in the intake, it started long enough to burn the fluid then died, i bought a filter and still nothing, i honostly dont think its the pump because the relays and fuse's are fine, it has two tanks both with gas in them, both tanks have in-tank pumps and its a 94-95 ford F-150 with a straight 6/300 4.9L. any ideas what to do?

mack1

Hi FML,

It just so happens that I have the electrical diagram for your truck. Two pictures are attached below. Click on each to enlarge. If you want to copy them to your computer, right click on the enlarged image and pick COPY. Then open Microsoft Paint and select PASTE on the files dropdown.

There is only one fuel relay as shown on the first print. The Powertrain Control Module (PCM) controls it. Notice that there is a branch wire at the very right of the print that says "To Inertia Fuel Shutoff". It is pictured on the second print. The wire is colored Dark Green with Yellow stripe (DG/Y).
The switch is normally closed unless you hit something headon, then it opens to disable the fuel pumps. From there, a Red with Yellow stripe (R/Y) goes to the fuel selector switch in the cab. From there, a wire for each pump. To the front pump, a Red wire (R). To the rear tank, a Brown with White stripe (B/W). From each pump, there is a Black wire to chassis ground.

Before you do any voltage checks, open the door and listen as you move the ignition switch from off to on (not start). The selected pump should pump for 2 seconds and shut off. See if you can hear either one. Note that the PCM keeps the pump relay engaged if the engine starts. If neither pump runs, you likely have an electrical problem and you will need the prints.

Also, how did the problem start. All at once, or been acting up over time?

If you have a volt meter or test lamp, I can step you through the process of tracking down the problem.

Let me know what you find.

Very best regards,
Mack1

95Ford3a.jpg

95Ford6a.jpg

FML

well as for how it started, its a manual, i started it up and put it in reverse started going and it died, i didnt kill it it just died, since then it been doing this. also i tested the wired for the pumps, im not sure what they should be but the is 4 wires in a square 1 on each pump so 8 wires total, when i tested them both sets did the same thing, 2 of them had voltage when connected with the ground and the third one had no voltage im guessing thats the return whire for my pumps,

also i was talking to some people at a shop and they brought up the fact that on trucks with to pumps they also have a booster pump in the line, could that be the problem?

as for hearing if the pumps turned on i tried but i couldnt hear anything mainly because my truck is outside and it was really windy at the time

mack1

Hi FML,

My grandson has a truck just like yours, same year, model, engine, and dual tanks. There is no booster pump on your truck.

At each pump, the four wires should be two for the pump and two for the gage float.

You can't measure the voltage for the pump without help. Remember that voltage is only there for two seconds when someone turns the ignition key from off to on. You get two seconds each cycle from off to on, so have your helper to keep repeating the action till you are sure of your measurements. Look at the color of the wires to know which wire you are testing. I called the colors out on the last post and they are on the prints.

Check your fuses again. According to the prints, there are two fuses for the pump relay.

Were you able to get a copy of the prints onto your computer?

The Inertia Fuel Shutoff is bolted onto the frame at the front of the truck (if my memory serves) and easy to get to under the truck. A small block about 2 inches square and about half inch thick. Look for a Dark Green with Yellow stripe wire on one end and a Red with Yellow stripe on the other. Look for the 2 second, 12 volt signal there.

Let me know what you find.

Best regards,
Mack1

wrench97

Check the collision switch should be a black box on the firewall near the parking brake pedal it has a little steel ball designed to be knocked off the contacts and stop the fuel pump in a collision and should have a reset button on it.

mack1

wrench97---Thanks. They say the memory is the first to go, but I don't recall what is next

FML--- Go to the location wrench gave and find the wires to be measured there.

Best regards to you and wrench,
Mack1

SABL

Good place to check.... the shut-off is designed to stop the flow of fuel in the event of a collision. The location of the reset button is something good to know.... I have seen them "trip" just from a rough road. The worst one I dealt with was hidden in the trunk and above the left wheel-well..... that was many years ago. The location was so remote that I never actually saw the reset button but was able to do a reset by feel. In many cases when dealing with automotive work, feel is your best asset.

FML

HEY ALL. so i checked my fuel pumps the way you told me they where not the problem so then i checked the inertia fuel shut off thing and it turns out that was the problem, i appritiate all your help very much and im thankful for you all saving me alot of money :).
so thanks for everything and i hope i can help all of you in the future as well.

mack1

That's great FML.

Have a nice day,
Mack1