I have an 89 Ford F150, dual tanks, and it started stalling out and wouldn't restart about 2 months ago. I thought it had run out of gas, since the fuel guages don't really work, well, the front sort of works, but the back doesn't work at all.

Once I got it started by adding fuel to the front tank, but I think that may just be a coincidence, because other times, just letting it sit for a couple of hours resulted in it starting.

It has gotten worse, and now I can't get it to run for more than a few minutes after it has been sitting for awhile.

It is down the street, and I will have to try to fix it on the side of the road.

It will start on starting fluid, and runs as long as I spray it in the intake.

It sounds like no fuel, but since it won't run on either tank, I was thinking both tank pumps couldn't have failed....

Not sure exactly how to check the fuel pressure, is there a point that is normally used?

Any ideas would really help. Luckily, it is on a subdivision road, so not much traffic, but I have to move it from in front of the house where it is soon.

Thanks,
Bill

 

An 89 also has a fuel pump in the frame rail. Do you hear the fuel pumps run for a second or two when you turn the key on? What engine do you have?

 

V8 302

I might have to have someone turn the key on while I listen. Where is the best place to listen, near the tanks?

Thanks!

 

If everything around you is quiet, you can easily hear it from the drivers seat.

 

OK, we drove down, turned off the radio and heater, and then turned the key on. I heard what sounded like a slight click, one click, towards the rear. The starter turns it over fast, but it didn't start.

We turned the key off, swapped tanks, and turned it on again, still sounded like just one click.

I never really noticed what the pumps sounded like, but other elec pumps I have heard sound like a series of dull clicks, that slow down and then stop.

Bill

 

There are 3 fuel pumps. One inside of each tank and one bolted
to the in side channel of the driver side frame rail.

In front of that pump is the fuel filter which looks like a small
metal can.

Each in tank pump has two fuel lines that feed the tank selector
valve which is also bolted to the driver side frame rail towards the
back end of the truck.

The larger line is the supply line from the pump. The smaller line
is the return line. (Total of 4 lines at the back of the fuel tank
selector valve).

The fuel flows thru the tank selector valve to the input
of the frame mounted pump. Fuel then goes to the fuel filter
then to the fuel rail on the engine.

On the engine fuel rail is a schrader valve. Usually there is a
cap that screws on to it to cover it. It looks like a short valve stem
on a tire. You press on the valve stem/core and fuel should
squirt out of it. The fuel pressure should be close to 40 psi.

You can also verify you have fuel flowing by disconnecting the hose
at the inlet or outlet of the fuel filter.

The hoses have a plastic clip you can pry up with your finger or a
small flat blade screwdriver. Pull the clip half way up. Then pull
the hose off. Point the hose in a container if you can, and
crank the engine. You should see fuel pouring out. If no fuel,
move back and disconnnect the hose on the back of the frame
mounted fuel pump. Verify if you have fuel going to the pump.

If no fuel, move back to the 4 hoses on the back of the tank
selector valve. The two larger hoses are the output
hoses from each tank.

Remove each hose and see if fuel comes out of either hose
when you crank the engine. The hose that should have fuel
coming out of it will depend on which tank is selected.

To reinstall the fuel lines you push the clip back into the hose
connector and then push the fuel line back on.

You should feel and hear a click which is the plastic clip tabs
locking back in to place. Tug on the fuel line to make sure the
plastic clip has seated and the hose doesn't pull off.

Here's a picture of what the clip looks like. There are two
different sizes used on the fuel system. Black ones and White
ones.

 

Thank you very much. I think I am following all of that, and will start through the checks!

 

In case you did not follow all of that here is a diagram and photos of what he said.









No filter inside in your 89.


/

 

Thanks everyone for the great help, blow by blows and diagrams!

I found all the components, slightly different placement from the photos. My hp pump is basically under the drivers door nested in the frame, and the filter just ahead about a foot towards the engine.

I didn't get any fuel pumped from any pump, including the last pump, when the key was on, or when the key was turned to start. Some fuel runs out of the tank lines when you pull them off, or when you pull the inlet to the main pump.

I put a voltmeter on the main pump, took a bit to probe the pins, and measured key on, and key to start, and there is no voltage at all.

I don't know if that is good news or bad news, but it appears they don't pump because there is no voltage. I am hopeing someone tells me that is good news.

Thanks,
Bill

 

There are two relays mounted on a bracket
behind the air filter box driver side plastic fenderwell
panel towards the power brake booster. There could
be a plastic cover covering the two relays.

One relay is for the computer and one relay is for
the fuel pump.

Here's the schematic that shows both relays.
This is a 88 schematic so your 89 could have different
color coded wires. The actual wiring should be the same.

Since you're dead on the road and need to get the truck
running, find the fuel pump relay and pull it out of its
socket. Take a piece of wire or paper clip and jumper
the relay.

The relay in the 88 has four wires going to it
red wire and tan/light green wire are the primary relay
coil. A Yellow wire which is 12 volts and a Brown wire
that goes to the fuel pump. If you short the Yellow wire
to the Brown wire and turn the ignition on, the fuel
pumps should run.

The first schematic shows the fuel pump relay.
The bottom schematic shows the fuel pumps and how they are wired.
Hopefully you can figure out the wire color codes.

People have also found corrosion and bad wiring at the fuel pump
relay socket. There is also a inerta switch shown in the 2nd schematic
that opens the circuit when in a collision. It's mounted on the
firewall inside the cab driver side foot well. It has a button that can be
reset if it trips.

 

Also check that the small black wire with a green stripe leaving the NEG (-) post of the battery has a good connection or the engine will not run.

Shorting the Tan wire with a light green stripe to ground should pull in the fuel pump relay, this wire is found at pin #6 of the self-test connector. You can also short the Tan wire with a light green stripe to pin #2 of the self-test connector (2 & 6 shorted with a paper clip).

The Brown wire shorted to the Yellow at the fuel pump relay will run the pumps all the time with the key on or off.
The EEC & Power relay is for all the power for all the Injectors, solenoids, relays & the computer.

The below diagram might show this a little better.





/

 

Subford, F150XLT and 88N94, thanks a bunch. It is fixed!

What I found was the yellow wire at the relay corroded out and laying in the engine compartment out of the socket. The relay wasn't in the holder with the other relay under the cover, it was just laying on top of the inner fender, which left it more exposed.

I did finally find the inertia switch ok, but never did find the test connector. There was a similar connector for the computer, but it had an extra pin or two, and the wire colors didn't match.

Regardless, the truck is home in the driveway, once I found the yellow wire, it didn't take a minute to get it going. I still need to pull the connector apart and re-crimp the wire, and secure the relay properly but otherwise, finished!

Thanks so much, I was really stuck and in a bind. I printed all the thread off, and it is staying in the truck!

Bill Harris
B'Burg, VA