OK guys.....hope you guys can help me get outta a jam as always. Yesterday going to work my truck just died as if turning off a light. Got the truck towed home. BTW....1998 F150, V-6, Automatic, 2 X 4. OK, I did have the fuel pump go about 2 years ago. At least then it was giving me warnings that the pump was going bad. Any this is what I have check and done so far and from reading other post on here. Fuse good, power at relay good, no power at Fuel pump and power at inertia switch. Now at the inertia switch I do have 11.70 volts on the smaller wire, I think it was yellow when the ignition is turned on, but the red and green nothing. So what I can figure so far that I am not getting any power from the relay to Inertia switch. There was one test that I read to jump 30 & 87 and see if my test light comes on. It didn't. So I changed the relay with a known good one and still the same thing. I can't figure out how to remove the Power distribution box to check the wires for connection. Bottom line, I am lost and any help will be greatly appricicated. Thanks for reading.

 

If your testing with the ignition in the RUN position you will not get the pump to run.
At ignition to RUN the pump will only be powered a couple seconds, then shut off. Are you missing this?
If you connect a meter to the leads from the Inertia switch to the pump and go through the sequence you should see voltage for the couple seconds then go off.
If you begin cranking, the voltage should reappear full time.
This all happens under PCM control.
Here is how the circuit is divided;
Fused power is applied to the relay to be passed to the pump.
However, the PCM provides ground to operate that relay.
.
Of note, the PCM is never asked to handle any more current than is necessary for reliability reasons so uses 'slave' relays where possible.
The pump draws about 7 amps +/-.
.
You have two places for an issue along with the wiring.
Test each operation separately from the pump back toward the switch then the relay to see where the problem is..
The pump circuit is divided this way to offer some protection in case of an accident, so the pump does not feed a fire, if power remains applied in some manner.
Just take it in sections and you will come to the problem area or prove the pump faulty..
Good luck.

 

Hey Bluegrass....Long time no see. Hope you are doing well these days. Ok....I have done all you mentioned above. I know about the 2 sec light when turning the ignition on. When I tested at the pump, no voltage. (BTW, pump is good. Hot wired it and it ran) Traced back to Inertia switch, no voltage. Traced back to Relay, have 12.5 volts coming in but don't know if it's going out. I am thinking it might be the eec relay? Got that from reading other post. You think it might be? And where is the EEC relay located? Thanks for your reply.

 

Hello,
to verify, put voltmeter on leads to the fuel pump, then turn ignition on.
If you see voltage at that point for the 2 seconds interval, the PCM is being powered up ok because it is operating the pump relay off the 2 second PCM internal timer.
This will cover operation of both sides of the system.
Once cranking begins the PCM detects crank rotation from the crank sensor and 're-operates the pump relay full time.
If you see voltage going toward the pump then it has to be an open in the harness or even a loss of 'ground'.
I don't remember your name unless you know me form one of the Lincoln boards some year back..
Good luck.

 

I'll give that a shot tomorrow. I know you from many times you assisted me in other problems a couple years ago and I really appriciate all the help you have given me in the past.

 

The PCM must see an accelerating crank signal, indicating the engine is firing, before it turns the fuel pump back on. If the engine doesn't fire while cranking, the fuel pump stays off except for the initial 2 second priming cycle during that starting attempt. The ignition has to be switched OFF before starting a new cycle.

 

I did not know that! It's been a while since I got some new info off the board.

 

OK.....I had my in law assist me in checking for voltage. Put voltmeter with T-pin at pump, turned on ignition, nothing. Check voltage at Inertia switch turn on ignition, nothing on Green or red wire but the smaller wire I think its yellow has voltage and I do have voltage on #30 pin of the pump relay.

 

If you did it right, then the PCM is not being 'powered up' if you did not see the initial pump signal.
On cranking, yes there is more to it than just cranking, I always leave out.
If the crank sensor signal does not result in spark, fuel pump is not activated again.
The first pump run for the short time interval is from initial 'power up' that causes a circuit timer to ground the pump relay.
The timer has a very short time constant.
Once the conditions for starting are satisfied the timer is pulsed continuously to keep ground on the relay.
You can see from this that if the engine stops the timer releases the pump relay. That's one of the safety features built in. However very often it causes people to chase a problem that is not there because of the way it works, by design.
Good luck.

 

So if the PCM is not being powered up, what would the problem be? I know my relay is good, so is it just the PCM went bad or the crank sensor or something else I need to look for?

 

Here is another thing I found. If I jump pin 30 & 87 at the fuel pump relay, the fuel pump runs. Just won't do it when I turn the ignition switch on. I 'm am lost!!!!

 

Something else I noticed. As I stated before, I can jump the fuel pump and it will run. But if I pressurize the fuel rail and try to start the truck, it will not fire. Also, when using the scan tool, it does not communicate with the PCM. It says "unable to link" I know the scan tool works cause I checked it on my wifes car.

 

You've been checking too far "downstream". Your symptoms appear to be of a PCM that is not powering up which must happen before the fuel pump can run or the ignition can operate.

Quick check for PCM power: Does the Check Engine Light come on when the key is turned from OFF to RUN. If "yes", the PCM is getting power. If "no", then either the bulb is bad or the PCM isn't powering up.

 

Scan tool not communicating with the PCM is a pretty good indicator the PCM is has an issue.
Now can you see why the pump will not run?
It is PCM controlled.
Look in your owner manual pages 210, 211 and 212.
Fuse 2, what does it say?
Fuse 18, what does it say?
Fuse 111, what does it say?
Relay 304, what does it say?
Location 501, what does it say?
Check all these out with an ohm meter to be sure.
The relay contacts may be faulty etc.
You will pull all these location out so if it is seating, you may clear the trouble.
If the PCM has lost power, it will cause the PCM to clear it's dynamic memory and launch into a full diagnostic.
As long as it is working on the diagnostics the code 1000 will be set.

If you should find a blown fuse, then you need to think what might have caused it or it might happen again such as a 501 fault or even the capacitors on the fuel and coil leads have shorted, for example.
Good luck

 

Bluegrass.....Pages 210, 211, and 212 in my owners manual are lubrication and dimensions. No where in my owners manual do I see a Fuse 111, Relay 304 or Location 501. Fuse 2 and 18 I see under the dash fuse box and under hood fuse box.

ProjectSHO89....did what you said and no CEL when key from off to on.