[font size="1" color="#FF0000"]LAST EDITED ON 29-Aug-01 AT 03:20 PM (EST)[/font][p]First things first. Do not, I repeat, do not apply voltage or ground either of the ECC (Engine Control Computer?) connecters. There is a strong posiblity of damaging the ECC.

Ok, let me give this a try. Now, on the Fuel pump relay, you stated that you have 12V on the pin from the Batt. You also Stated that you have 12V on both of the pins marked To ECC and From ECC, correct?
Now, try this. Ground your meter and place the other probe on the From ECC connector, turn the key on, your meter will either read 12V or 0V. Now do the same for the To ECC connector, it should read either 12V or 0V. Now, the readings should be this, From ECC or To ECC should be 12V, the other connector should be 0V (with the key on). I don't know if that makes sense, so let me explain it this way. If you have 12V on both the To ECC and From ECC, this is bad. That means the ECC is not grounding the relay and turning the pump on. Either you have a bad wire to the ECC or there is someother problem with the ECC.

I hope that made sense.

Roger Lane
Test Analyst
Sr. Automated Test Engineer
IBP, Inc.

 

Question.... is there a way for me to hot wire the relay and silmulate it's operation? What I am thinking is for example, I pull the relay, take the terminal on the relay that would go to the line for the pump and wire it to the terminal it would connect to on the Power Distribution Box. Then run a wire directly from the battery to the "hot" terminal on the relay. Now can I take another wire from the battery and touch it to one (or both) of the other two terminals on the relay that get power when the key is in the "ON" position and simulate what is suppose to happen?

What I am thinking is if that works then the problem would be in the Power Distribution Box or one of the lines before it.

So if I then wire one of those "ON" position terminals (on the relay) one at a time to the power distribution box, one of them (the one with the short) should cause the motor not to work. The one that causes it not to work should be where the problem is.

Follow me? Am I loosing it? That does not even make sense to me now.

 

Lessee:

Seems like everyone is looking between the relay and the pump on the POSITIVE SIDE.

you've got 12V to the pump connector. (pump disconnected)
With the pump connnected you get 0V (Near short or open in the line).

Hook up the pump direct to battery and pump works fine (assumption made that this connection is NOT THRU wiring Harness)

I'm thinking he lost the ground from the pump connector to the frame......

Has the ground from the tank connector to frame been checked for resistance or corrosion. Check each pin from both sides of the connector for continuity. High resistance values here will show up as a NO GO.

Clamp a wire via (visegrips and 12Ga wire) to the tank (clean off and area of the seam and clamp there) and a clean ground on the frame. Connect the pump connector. Leaving wiring in NORMAL CONFIGURATION (NO JUMPERS other than above) turn on KEY.

If pump works (and theoretically it should) then you have a grounding problem in the Harness or connector. Look for corrosion in the connectors and do a resistance check on ANY and ALL ground wires and terminals. High resistance will cause an open.

Also check the computer (EEC) for corrosion at the terminal junction block.

 

Couple of observations

Ok is an EEC the same as ECC?? As the schematic reads EEC not ECC. I assume both are some sort of computer control unit.
The way I see it, on the schematic, the power for the coil of the Fuel Pump Relay is a direct 12 volt line that is controlled by another relay that is mechanical or electronic as in solid state magic stuff I cant see how connecting 12 volts to the Fuel pump relay coil would have any bad effects, as the circuit is designed to have 12 volts on it. The ground circuit for the pump relay coil could be a different matter, I don't know as it is not clearly shown on the schematic. So maybe putting a ground isn't a great idea without more info.
Also I can't see how it would be a ground problem for the pump, since when the fuel pump relay is bypassed the pump runs as per normal. Hence the ground is good, the power circuit is good, the pump is good.
Since the fuel pump relay was replaced it isn't the problem, unless by some stroke of luck the new one was no good as well. I still am leaning towards the problem being in the controlling circuits for the coil of the fuel pump relay.
Looking at the schematic again how does this sound for a theroy?
The 12volts for the pump is taken from the same fuse link as the 12 volts to close the fuel pump relay. So what if the circuit isn't delivering enough to operate the pump as well as close the relay. It can either close the relay or operate the pump but not both together.
So when the relay was bypassed the pump worked. But when the relay was energised it couldn't handle both......... just a theory you know I mean how much power does a relay need to close, not very much I would say.
Maybe a thorough check of the fuseible link, connections and wiring in the fuel pump relay coil circuit would be a good idea???
Still throwing out theories and hoping for the fix.

Sparky

 

OK, I just thought about this a little more. I think the best way to test this is this. Remove the fuel pump relay, place the leads of your DVM where the coil of the relay should go (Too EEC, From EEC). Set the meter to read Volts. Turn the key on and see what it reads. If it reads 0V, the EEC is not turning on the relay, if it reads 12V, the EEC is working correctly.
I hope I'm not confusing anyone. These things are a lot easier to fix when they are right in front of you. That's why I got out of the Phone Tech business. ;-)

Roger Lane
Test Analyst
Sr. Automated Test Engineer
IBP, Inc.

 

Ok how about this twist. Wouldn't the EEC have to be turning on the pump relay at sometime since he can measure 12 volts at the pump connector when it is disconnected from the pump?????
Another wild stab here, using my limited EFI experience-read none , does the pump run all the time or is it shutoff by the EEC when the fuel pressure is built up and not being used??? Example the key is turned on and the engine isn't running. And maybe with the pump disconnected the EEC doesn't sense the requirement to turn it off.
So maybe the pump circuits are functioning properly. Why not try jumping the pump relay and trying to start the truck when the pump is "forced" to run. Or would this mess up the EEC???
Lots of maybe's in this post, eh
So possibly, see I didn't use maybe , the reason the truck won't run is spark or lack of fuel injectors being triggered related not fuel related and we are chasing ghosts.
Any input on these ideas guys???????

Sparky

 

Well.... I am just about ready to give up on this.

I disconnected the negative battery cable. Then I connected the positive lead on the volt meter to the positive lead at the pump connector. I ran a wire from the negative battery terminal to the back of the truck and attached it to the negative on the volt meter, as soon as I turned the key to "ON" (remember the negative battery cable is not connected) I get 12 volts. I then put the connections on the pump 0....

I think this would rule out a broken ground, correct?

I am tired!

 

Should I be able to cross a wire on the relay and get the relay to click like the starter relay? The relay DOES NOT click at all, I thought it did earlier but have determined that it does not.

http://www.atlanticjetsports.com/temp_stuff/F150rly.jpg

 

If the relay doesn't "click" how in the heck is voltage getting to the pump connector????? There must be another path for voltage not shown on the schematic.
With the pump relay removed, and set over on a bench, no where near the truck, can you measure 12 volts at the pump connector??
Better yet do you live anywhere on Vancouver Island, BC I would love to meet this truck
One of those "hot when key on" terminals should be a ground. Unless this relay works on different electrical potentials. Meaning if one side of the close coil is 12 volts and the other side is less than 12 volts, the relay considers the less than 12 volts to be a ground as it is more negative than 12.
Whoa, here comes that solid state theroy I learned years ago and never really liked
Come on guys help us out here.

Sparky

 

Hey Sparky,
Just checked again... With the relay out I get at the Power Distribution Box a 12v reading on the hot lead from the battery, 0 volts on the lead to the pump, 12 volts on one of the "ON" leads (#1 in photo) and about 7 volts on the other "ON" lead (#2 in the photo).

Now if I run a jumper from the hot battery lead to the pump lead it works. From lead #1 to the pump lead it works. From lead #2 to the pump lead it does not work.

 

sparky,
thanks for all your help!!! it is really appreciated....unfortuneately we live in central NJ, USA. again thanks for all your help!
adrian gennusa

 

GmanPride45: Took me forever to read your post! It started to sound like something I had read over four years ago. Allow me to lead you to your problem: (cool website like this one!)

Go to: MrFixit.com

scroll past lots of banners and click on: Stories from readers
then scroll down to: Hints and tips for auto repair field.

about the third choice down should read something about:
A FORD TRUCK THAT WON'T START.

Read this article and let us know if this was your problem.

Hope I could help.

Shotgun...

 

Ok that almost makes sense
The 12v from the battery and the 0v on the lead to the pump are correct readings.
The 12 v on the #1 lead sounds correct also, that is the voltage to energise the relay coil and close the pump relay contacts thus allowing power to the pump motor.
The 7v kind of sounds right, but since it is the ground for the pump relay coil I would expect 0v. But here comes that more negative logic again Since 7v is more negative than 12v maybe it is the correct reading ???
Anyway I am getting a manual for this fuel injection system tomorrow, if I get a chance. Hopefully when I read it I will gain some insight on this problem and hopefully how to fix it.
I don't suppose there is any chance that the new relay is broke, or that you know someone with a similiar truck you can try the relay in to check it? Well, maybe not a good idea it could spread the virus to his/her truck
Anyway don't give up yet. Hopefully the manual will enlighten me

Sparky

 

I guess that is just about as far from the West Coast of Canada you can get in the USA isn't it. Oh well I would have made a closer trip.

Sparky

 

Excellant story, check it out, it could be the answer

http://www.misterfixit.com/ottowire.htm

Just a side note since the relay can be jumped and the pump runs , the problem described in the story could exist on the wires for the power or the ground circuit for the fuel pump relay.
Sure hope this solves it.

Sparky