86 X19 fuel pump..

[Dan Sarandrea (Phila)]

Not sure if you know this or not, but with the stock FI system, the big fat red wire on the rear connector of the relay is battery power, it is not fused and not switched.

It is the second smaller gage wire that is molded into the stock Pos battery clamp (the other smaller gage wire is of course the brown wire to the fuse box), goes directly from the battery Pos to that rear half of the relay.

 

[TajMan]

At this time I am going to try and test some of the ECU terminals..

 

[TajMan]

excuse some ignorance, I didn't even know the ECU was in the spare tire well, because my car had sound deadening material covering it all up.

Are these pins correct?

If those are pins 10 and 20, I'm showing continuity at this time with the flap closed and the key off. This is a problem right, maybe what is keeping my pump running- a faulty flap switch? But at the same time this shouldn't happen with the key off correct?

 

[TajMan]

The switch is tested by using a VOM at the ECU end of the wire harness, the long plug-in part. Unplug the ECU connector and connect an ohmmeter between terminals 10 and 20. When the flap is open, there should be continuity (no resistance). When the flap is closed, there should be no continuity (infinite resistance).

Are these terminals correct?

Right now, key off and flap closed, I'm showing continuity between these two pins if those are 10 and 20.
This is a problem, correct?

 

[sdlsaginaw]

I'm looking at the schematics. As far as I can tell, the fuel pump part of the dual relay should only be able to close and power the pump via 88D under the following conditions:

1) Voltage is applied to 86A, which SHOULD only happen with the key in START

- OR -

2) Voltage is applied to 86C which SHOULD only happen with the key in START or RUN
WHICH CAUSES
The dual relay to apply power to the injectors and the AFM by switching 88Z power to 88A/B/E
AND THEN
The flapper switch in the AFM must be activated indicating airflow, or be misadjusted, or 88A and 86B are shorted in wiring

- OR -

3) ECM or wiring short leaks enough voltage to 86B via ECM pin 20 even if AFM is inactive or unplugged

- OR -

4) ECM or wiring short is backfeeding enough voltage to 85 via ECM pin 28 (unlikely, and pump would ONLY run with key off too)

 

[budgetzagato]

Yes...

Those are 10 and 20. I just went and verified this on my L-Jet-converted Scorpion. At rest 10 and 20 are not connected, when I press open the AFM flap they are. This is the flap switch inside the AFM.

But, as you said, pressing open the flap should not activate the pump (via the relay) unless the key is on. Check your white plug at the dual relay. The wire that goes to 86c, pink/black, is ignition switched power and should only be hot if the key is on.

The only other power source should be the 88y wire, brown/white, which is fused power. Check that these wires aren't jumpered at the white plug.

Edit: Another power source is the large red wire at 88z.

 

[TajMan]

couple things

AFM here. I saw on the spot I have indicated with red line, it appears this rod is supposed to hold an electrical contact open when the flap is closed, however my AFM could have been misadjusted and it was not doing such.
https://www.youtube.com/watch?v=NPYc2dmnCkc&feature=youtu.be

I bent the rod slightly, so that contact is held open when the flap is all the way closed. Tested, fuel pump still runs as soon as the dual relay is plugged in. Not sure what is supposed to be correct there.

Also, testing continuity between the coil signal wire and ECU pin #1, I was getting inconsistent results. Most of the time no continuity, sometimes a flicker of something on my volt meter.
Looks like I need to attach a new terminal on the coil end, and test some more..

 

[strangepod]

Something is just not right. As others have said the pump should never run with the key off – period. Even if the flap or the AFM was malfunctioning this cannot cause (that I can tell) the pump to turn on with the key off.
Check the following with the key OFF and the relay removed
Check for voltage between 86A(BRN/WHT) and 85(WHT – DO NOT GET THIS CONFUSED WITH THE WHT ON 88C OR 86), it is reading :___________
Check to see if the WHT wire on 85 goes to pin 28 on the ECU.
With the relay removed check continuity between 88D and 88Y, you should get none.
The only other thing that comes to mind is make sure that the connectors are plugged into the correct spots on the relay and in the correct orientation (don’t know if it is possible to get it wrong).


John

 

[jvandyke]

 

[TajMan]

I want to go crawl in a hole and DIE... the embarrassment!

Ok, so, it appears you can plug the black and white connectors in the opposite spots on the relay! I had seen they had pins in different positions, I thought I had checked right and plugged them in the correct spots... but I was wrong I had them switched!

I'm so sorry guys! oh god.. :confuse2:

The car starts and runs ok now! I'm sure I had a bad fuel pump that caused this problem originally. AFM malfunction fixed now too, as well as signal wire on the coil.

Lessons learned, new tools gained Noid lights from Harbor Freight.

I'm sorry again guys, you are all too good.
You had it right..

The only other thing that comes to mind is make sure that the connectors are plugged into the correct spots on the relay and in the correct orientation (don’t know if it is possible to get it wrong).


John

 

[jvandyke]

That hole is usually occupied by me, but there's room for all of us!
All that matters is you got it in the end!

 

[strangepod]

Been there, done that and got the t-shirt..
Wana hear a story about changing the timing belt and getting that 'accessory' gear out of sync? - no you don't...:wall:

 

[jvandyke]

how about tearing down your motorcycle engine, getting the head down, misaligning the cam, crunching the valves, doing it all over and missing the huge yearly bike trip, all because "I heard a noise" that ended up being a loose drive chain......yup, that was me!

 

[budgetzagato]

Ooops...

I want to go crawl in a hole and DIE... the embarrassment!
Ok, so, it appears you can plug the black and white connectors in the opposite spots on the relay! I had seen they had pins in different positions, I thought I had checked right and plugged them in the correct spots... but I was wrong I had them switched!
I'm so sorry guys! oh god.. :confuse2:
The car starts and runs ok now! I'm sure I had a bad fuel pump that caused this problem originally. AFM malfunction fixed now too, as well as signal wire on the coil.
Lessons learned, new tools gained Noid lights from Harbor Freight.
I'm sorry again guys, you are all too good.
You had it right..

I didn't think that was possible. But, at least you found the problem! And fixed a few other things along the way.

And tools! :headbang: