87 Ranger 2.9- No power to fuel pump

wollnutz · May 28, 2016

Hello I have a 1987 Ford Ranger with 2.9 v6. The previous owner took the fuel pump off the frame rail to replace and apparently gave up after that. I got a new pump and put it back together, but when I turn key to run I do not hear the pump engaging. The motor will turn when I turn key to start but it will not fire up because I am not getting power to fuel pump.

So far I have bypassed the inertia switch because it was popped up and able to be pushed down, but would not stay down. I also cleaned the connections on both of my relay plugs on the passenger side fender wall. They were gunked up with what appeared to be very old dirty grease- after I did this and tried cranking the motor one of the relays made a buzzing or whining sound for a few seconds after the motor stopped turning, which wasn't happening before. One relay is broken and taped back together. I ran down to Napa and got a new relay (they only had 1 in stock) when I plugged it into brown plug the dash lights up in the run position (it didn't do that before) when I put the new relay in the green plug nothing changed but then the dash didn't light up. Should I get another relay in case they are both bad? They are Ford relays and look old and crappy.

I'm not really sure what else it could be besides a bad wire somewhere. I'm not great with electrical so any advice would be appreciated.

Thanks!

RonD · May 28, 2016

Welcome to TRS

Brown base is the EEC relay, this powers the engine systems, computer(EEC), AND the fuel pump relay, not the pump just it's relay.

Green base is the fuel pump relay, computer controls this by Grounding it

So without the Brown base relay ON, the Green base relay can not work, it can not turn ON to send power to the fuel pumps.

So you will need 2 working relays

12volts = Battery voltage, so measure battery voltage first, if it is 12.5volts then 12volts = 12.5volts.
when testing voltage at wires lower voltage means corrosion, usually at connections.

Brown base relay socket should have 1 slot that shows 12volts with Key OFF
Green base relay socket should also have 1 slot that shows 12volts with Key OFF

These are Fused power wires, 30amp fuses for each

Then with Brown relay in place, Green relay socket should show another slot with 12volts when key is ON.

If voltage is lower then wire connections are corroded, between brown base and green base.

enjr44 · May 28, 2016

Here is the diagram. http://www.therangerstation.com/tech_library/EDiagrams/files/Diagrams_ElectronciEngControls2_9_1of3.JPG

As you can see, the EEC relay powers the pump relay (and everything else). EEC stays on; however, the computer removes the ground to the fuel pump relay after 2 seconds and does not turn it back on until engine rpm is above 400.

And of course it is possible to have two bad relays, just unusual. It could be a bad fuse or wire or relay. Take a wire from the positive bat terminal and jump it to the pump wire at the inertia switch. If pump runs you know problem is before the inertia switch.

wollnutz · May 28, 2016

Thanks for the replies. I just put in the 2nd new relay and still no power to pump I will test connections with multimeter now

wollnutz · May 28, 2016

Both connections do have 1 contact at 12+ volts

RonD · May 28, 2016

As said by enjr44, there will only be 2 seconds of fuel pump power when key is first turned on.
You can cycle key off and on repeatedly while listening for pumps to come on, or watch volt meter hooked to inertia switch in cab

By the fire wall on drivers side or passenger side there should be a OBD1 connector, it just hangs on the main wiring harness.

Drawing seen here: http://www.therangerstation.com/tech_library/OBD_I.shtml

In the drawing the FUEL PUMP slot is labelled
That slot is to GROUND the fuel pump relay to turn it ON if Key is ON
You can use a Jumper wire from that slot to a good Ground and when key is turned on fuel pump power should also come on, and stay on, assuming fuel pump relay has that 30amp fuse power to pass on to fuel pumps

wollnutz · May 28, 2016

I followed instructions to bypass the inertia switch altogether, which seemed faulty to me based on research. should I test the wires that that were plugged into that switch for voltage?

wollnutz · May 28, 2016

I tested the wires that go to the inertia switch they are at 0 volts in run position and 0.15 volts when engine is cranking. I am assuming this has to be the issue. Maybe this wiring is corroded and not sending the 12 volts down to pump?

RonD · May 28, 2016

Test the voltage in the Green Base(fuel pump relay), remove relay.
Key off
You should have 1 slot in that base that shows 12volts(battery voltage)

If not then you have a blown 30amp fuse(in engine fuse box) or it could use a Fusible link instead of a fuse in 1987.

Fusible Link is a short(6") wire that will melt and separate without causing a fire if too many amps are drawn thru it.

These were hooked up to the Battery cable post on the fender mounted starter relay(solenoid)

So if you don't have engine fuse box with 30amp fuse, then follow Battery "+" cable to starter relay.
On that post there will also be several other wires, this is the main power distribution for the vehicle.
Fuel pump relay's fusible link will be connected there(blue wire), so will several other circuits fusible links.
Blue wire is spliced to the Yellow wire that you will see at the Green base relay socket
This yellow wire should have 12volts all the time, key on or off doesn't matter

Blue wire is the Fusible link

wollnutz · May 28, 2016

The relay plug has 12 volts on one contact. But it is not sending 12 volts to the inertia switch or pump when bypassed. The plug has exposed copper and doesn't look too good (for the wire that goes directly to pump) if the plug is getting 12 volts I'm assuming it can't be a 30 amp fuse?

I hooked a hot wire up from battery directly to high pressure pump on frame rail and the pump starts making noise but it still won't start! Is this because there is a low pressure pump in tank that isn't getting the voltage needed?

wollnutz · May 28, 2016

Update: with key on run position I get 12+ volts from every terminal of the fuel pump relay plug except for the one that sends signal to pump so it must be a bad connection in plug, or am I wrong?

RonD · May 28, 2016

Could be the contact, but............

Look here: http://www.reuk.co.uk/Automotive-Relays.htm

All automotive relays are the same, this UK site just has better diagrams.

Pin 30 is usually the 12volts from the fuse, and yes fuse is good if there is 12volts there.
Pin 87 is connected to inertia switch and will only have 12volts when relay is closed.
This is called the Load side of the relay.
Power can be reversed, i.e. pin 87 has 12volts from fuse and pin 30 is connected to inertia switch, wouldn't matter since the point of the relay is to pass that 12volts.

The coil in the relay is what connects pin 30 to pin 87, it is just a wire wrapped around a metal bar, so if you put 12volts on pin 86 you will see 12volts on pin 85, because it is just a wire.
If you were to Ground pin 85, when pin 86 had 12volts, then relay would close(click), metal bar becomes a magnet and pulls down a metal contact bar which connect pins 30 and 87

I assume you are measuring voltage with relay plugged in and testing the wires, which is fine.
But relay is open, so there would be no voltage on pin 87, you would need to ground the relay to close it and then test pin 87

wollnutz · May 28, 2016

As of now I used an alligator clip to connect from the next contact over to the wire that goes straight down to pump. Now when I turn key to run the pump will run continuously. I checked the line and the pump is primed. The motor turns and the pump is working but it still won't start. I'm not sure where to go from here.

RonD · May 28, 2016

The fuel injectors get fuel from the Fuel Rail, on the fuel rail will be a Schrader Valve.
Fuel rail is between lower and upper intake manifolds.

If you have ever put air in a bike or car tire you know exactly what a Schrader valve is, its the air valve on tires.

And that is what it looks like on the fuel rail, may even have a screw on cap like an air valve.
Works the same, press center pin and fuel should squirt out, so be careful, should have 30psi pressure just like a car tire.

You could also pull a spark plug to see if it is wet with fuel, if it is then spark is your problem.

Do a 50/50 test, spray starting fluid(ether) or gas into the intake, then try to start engine.
If it starts then dies you have a fuel issue

If it doesn't start then it is a spark issue

wollnutz · May 29, 2016

Okay I found Schrader valve and it did shoot fuel out so I know now that I'm getting fuel to rail. I also know I'm getting spark. I spayed starting fluid into throttle body and the truck fired up for a second or two and sounded normal. I must not be getting power to injectors. I tested the contact points on my EEC main relay connector plug and while 2 of them were at 12 volts and able to power my fuel pump hot wire and spin pump, the other 2 were at around 10.5 volts, which was not enough to engage the fuel pump. I was planning on getting two new connector plugs for both relays to see if that will solve voltage drop. I'm under the impression there is no way to hot wire injectors because they are not constant. If the connector plugs don't solve my problem could it be that my computer module is no good and not sending signal when and where it should?

87 Ranger 2.9- No power to fuel pump

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