97 Ranger no start

[sp53]

I have a 97 ranger 4 cylinder no start. The problem is fuel delivery, but I cannot isolate the problem. The bed is off the truck and the fuel pump runs when hotwired. I check the inertia switch, replaced the 2 relays under the hood, and check the fuses and replaced the electrical part of the ignition. I found some wiring schematics, but they show 2 wires going to the F pump and not 4.

My thoughts are possibly the mechanical side of the ignition is not picking up all the contacts or a broken wire. I want to run down the wires before I through more money at the truck. I went to our local Ford dealer, but they claimed they have no schematics for the truck, right! So, I was wondering about your thoughts, and if you might a more precise schematic for a 1997 ford ranger?

Thanks Steve

 

[RayInStl]

I would start by using a voltmeter to check for voltage at the relay. If you have voltage there, but not at the inertia switch, I'd start following wires between the two. Check voltage at any connectors along the way.

Does "I checked the inertia switch" mean you had power to and from the switch? If so, then that confirms relays and fuses are good. If that's the case, start following wires from the inertia switch to the pump. If you find a connector, test for power there. If there are no connectors between the two, you'll have to use a sewing needle or similar to pierce the wire and test it that way.

When trying to find a brake in a wire, it's best to test the middle first. If you have power at the center of the wire, move halfway towards the pump and test again, otherwise test halfway back to the inertia switch. Keep cutting the distance in half till you find the brake.

 

[RayInStl]

This link has a diagram that shows 4 wires at the pump.

https://www.justanswer.com/ford/2ir...-running-relay-switch-this-bad-fuel-pump.html

 

[Andy D]

The pair of V/w and V/Blk are for the gauge sender. Colors were differnt on the Rat but ..

The plug crumbled on me and after I got the thing going I checked the diagrams and they confirmed which was what. Then I soldered the terminals onto the pick up.

 

[telsar]

I have a 97 ranger 4 cylinder no start. The problem is fuel delivery, but I cannot isolate the problem. The bed is off the truck and the fuel pump runs when hotwired. I check the inertia switch, replaced the 2 relays under the hood, and check the fuses and replaced the electrical part of the ignition. I found some wiring schematics, but they show 2 wires going to the F pump and not 4.

My thoughts are possibly the mechanical side of the ignition is not picking up all the contacts or a broken wire. I want to run down the wires before I through more money at the truck. I went to our local Ford dealer, but they claimed they have no schematics for the truck, right! So, I was wondering about your thoughts, and if you might a more precise schematic for a 1997 ford ranger?

Thanks Steve

I just went through a similar issue. Look at BBB industries to see if they have your schematic. Its: http://www.bbbind.com/index.html

Make sure you have spark, also. Check your ODB2 codes.

Good luck.

 

[sp53]

they want 5 bucks for the wiring diagram, is that normal?
steve

 

[telsar]

I looked on-line and paid nothing and was not asked to pay anything.

 

[sp53]

Well I tried again and they still want money 5 at first with a balance of 25 for Ford mech, something stinks there.

Anyways, I have power at both relays but not at the inertia switch. Tracing the wires back from the switch would be easier with a diagram. The diagram I have shows a pretty simple set up for the inertia switch. Basically, one wire to the relay, one to the pump and one to an indicator light on the dash that the switch has been tripped. The whole situation seems odd, there was a quick stop and killed the engine resulting in a no start which would indicate the inertia switch tripped, but not a killing of the power to it. Does the bottom of the fuse tray separate from the top easily? It looks that way. My thoughts are to start there at the fuse box and work back to the inertia switch. I want to start were I see power at the wire. Could I still be missing something obvious and simple?

steve

 

[Andy D]

I wouldn't know an inertia switch if it bit me. But from hanging here, the way to deal with this, one wire in,one wire out, is to jump them and see if the truck will start. Good luck.

 

[RonD]

OK, first, you do know there is no power to fuel pump/inertia switch when key is ON
The Computer(PCM) will turn fuel pump power on(close fuel pump relay) for 2 seconds ONLY, when key is first turned on, then NO POWER after that until engine RPMs are above 400(engine started)

So if you are testing for 12volts at inertia switch it will only happen for 2 seconds when key is turn on, but it will happen EACH TIME key is turned from OFF to ON(RUN), so test for that

Yes, the wiring is pretty simple

Battery------30amp fuse-----------FP Relay----------inertia switch-----------------fuel pump----ground

Fuel pump relay has 4 connections, it can have 5 pins/slots, but only 4 are used
Coil 12v
Coil Ground

Fuel pump power pins
Fuse 12v
Inertia switch wire

The Coil only gets 12v when key is on, from EEC(PCM) Relay
And Computer controls its Ground, so only Grounded for 2 seconds
The coil in a relay is what closes it when it has 12v and Ground

Fuse 12v will have 12volts all the time, direct connection to battery via 30amp fuse
Inertia switch wire can be tested using OHM meter function on your Volt Meter

First ID which slot in Relay base socket is Fuse 12v, key off, its the only slot with 12v
Turn key ON, test which slot has 12v now, thats the Coil 12v
That leaves you with 2 slots that are not IDed
Get a long wire that reaches from engine fuse box to inertia switch in the cab
Put one end of the wire in un-IDed slot
Set OHM Meter to 200ohms or lowest setting as available
Touch meter probes together, you should see 0 OHMs, that means a direct connection between the probes

Now put one probe on the long wire end and the other probe on either wire of inertia switch, test both wires.
If 0 OHMs then wire is good
If not 0 ohms then switch long wire to the other un-IDed slot in relay socket
Test again

 

[sp53]

Thanks Ron you got me thinking. I did try to get a hot reading with a test light and ground on the inertia switch with no results, but I never considered that the power would come in 2 second blasts and perhaps I never had the test lead in correct spot at the correct time. I did open and close the inertia switch to check continuity and had it the first time I looked at it, by opening and closing. But my son and I tried it again and the switch made an odd sound like a rattling and shaking, maybe the switch is broken! Can I jump over the switch and make a forced run somehow?
steve

 

[RonD]

1997 inertia switch should have 3 wires
Dark Green(from fuel pump relay)
Pink(to fuel pump)
Grey(to dash light "fuel reset")

Green and Pink could be jumped(connected together) to by-pass inertia switch


Inertia switch has a weight inside, in a sudden stop(accident) weight keeps moving and breaks the contact between Green and Pink wires, and connects Green and Grey wire, to light up the "Fuel Reset" in dash
The red button on the top will pop up if that happens, if you push it back down it reconnects Green and Pink wires, but.........once tripped inertia switches have a tendency to "trip" again much easier, i.e. driving off a curb or slamming a door

Yes, should be 0 OHMS between Green and Pink wire connectors on inertia switch, they are connected, so switch should pass power to pump

 

[sp53]

Well I got it Ron and I appreciate your help; you kept me going. I switched around the 2 diodes and perhaps that did it, and I also put in a new heavy-duty battery.

I ran into similar problem with Saab 9000 in that the battery was strong enough to spin the motor over, but had voltage drop in other areas and would not run the pump. I left the diodes swapped for now; the one said PCM (Power control module) I guess it goes with the relay.

Thanks again George