Reverse Continuity at fuel pump relay?

harbinger · May 11, 2015

Hey guys it's been a long time.

My 89 bronco 5.8 efi will crank but no start. The PO had been using the "wrong" battery with the polarity backwards from the ergonomics of the truck wiring so a few things had been moved to make it look like it was supposed to be like that. anyway, long story short I hooked it up backwards.

I have been diagnosing the no start using these:

http://troubleshootmyvehicle.com/ford/4.9L-5.0L-5.8L/how-to-troubleshoot-a-no-start-1

http://easyautodiagnostics.com/ford/4.9L-5.0L-5.8L/eec-power-relay-tests-1

http://easyautodiagnostics.com/ford/4.9L-5.0L-5.8L/fuel-pump-relay-tests-1

EEC checked out all good, sprayed starter fluid into the intake and she started so I know I've got spark.

The relay was old and had some corrosion and I've already changed it out with another I know is working. I have probed the wires at the pump and am getting no power to pump.

I replaced a fusible link near the starter solenoid and all wires coming off starter solenoid have around 12volts (I checked after the fusible links, but maybe there are more to check)

I have power to fuel pump relay but when testing continuity to the ground on the relay, the light comes on before turning the ignition on, then turns off when the ignition is turned on. which is opposite of what should happen as far as I have read.

Jumping the #3 and #4 wires on the relay turns something on, but not the fuel pump. I hear a faint "pump-like" noise when they are jumped, but no fuel pressure and no auditory (sound) evidence of the fuel pump coming on.

hopefully you guys can help.I have a few pictures loading from my camera that I will upload in a minute

harbinger · May 11, 2015

I keep getting server error when trying to upload pics. You guys know what it looks like though. Just to make sure everything is correct though, I have a single wire running to the negative post coming from the wire bundle between the battery and the headlight, then the other to the engine block, the positive side connects to the starter solenoid with the connections that go to everything else on the firewall side of the solenoid, then wire on the S terminal runs into the big wire loom with all the rest, and the wire for the starter runs off the other post closest to the battery.

harbinger · May 12, 2015

So thinking through the problem. Since the fuel pump relay is grounded when the ignition is off, but not when on, I think my next step is to look for ignition switch failure. I will update, any other input is appreciated.

harbinger · May 12, 2015

http://broncozone.com/uploads/monthly_04_2008/post-8965-1208754232_thumb.jpg

then there is this, second column, second paragraph

so maybe it is misadjusted, but I'm not sure that would happen from a reverse polarity surge

harbinger · May 12, 2015

I also just noticed my g111 is burned up. I haven't been able to find where it connects too though.

http://broncozone.com/uploads/monthly_04_2008/post-8965-1208754277_thumb.jpg

all the way at the bottom of the image you can see the edge of the previous page. 89 ford bronco f150 g111 ground turned up nothing in google so here it is for those future idiots who burn wires in their truck for fun

Anybody know where g111 goes? I've tried uploading pics again today and no dice.

harbinger · May 12, 2015

Went by the junkyard, none of the f150s or broncos up there had anything or even a bolt hole where g111 is. I didn't have any tools with me, I might just go try and grab a wiring set and just rerun the wiring. Will update.

miesk5 · May 13, 2015

yo H,

Sorry about not being able to reply w/accurate info.

I have tried to locate that G111 Location and circuit(s) it serves; I could not enlarge that wiring diagram you attached.

One wiring diagram source is here; same as Ford EVTM (PARTIAL);

http://www.revbase.com/BBBMotor/Wd/DownloadPdf?id=21138

incudes a few diagrams for your 89 Bronco 5.8 EFI

FP Relay circuit and Fuse Link N (Blue)

Fusible links:

http://www.revbase.com/BBBMotor/Wd/DownloadPdf?id=21135

see more @ http://www.revbase.com/BBBMotor/Wd

Also;

Fuel Pump Circuit Operation

When the ignition is switched to the ON position, it turns the EEC Power Relay on. The EEC Power Relay provides power to the EEC-IV processor and the control side of the fuel pump relay. Power for the fuel pump is supplied through a fuse link or high current fuse attached to the starter solenoid (battery side). From the fuse link or high current fuse, current flow is through the fuel pump relay and Inertia Fuel Shutoff (IFS) switch to the fuel pump. The IFS switch is a safety device used to shut off the fuel pump in the event of a collision. If the IFS switch is "tripped," it must be reset by depressing the white or red button on the top of the switch. The fuel pump relay is controlled by the Powertrain Control Module (PCM).

When the ignition switch is turned to the ON position, the fuel pump will operate. If the ignition switch is not turned to the START position, the PCM will shut the fuel pump off after approximately one second. The PCM will operate the fuel pump when the ignition is in the START position to provide fuel while cranking.

After the engine starts, the PCM will continue to operate the fuel pump unless the engine stops, engine speed drops below 120 rpm, or the IFS switch is "tripped."

System Diagnosis

Note: Grounding the FP lead at the DLC will allow the pump to run continuously with the ignition switch on.

FP Wiring Diagram in an 89 from EVTM

Source: by Ford via SeattleFSB (Seattle FSB) at http://www.supermotors.net/registry/media/851787

Shows FP Ground as G801

G801 is located on the LH inner fender behind the headlamp & both pumps Grounds join @ Splices S155 & S903

Source: by Seabronc (Rosie, Fred W) at Ford Bronco Zone Forums

http://broncozone.com/index.php?app=core&module=attach&section=attach&attach_rel_module=post&attach_id=10092

Seabronc's diagram, should have battery voltage (over 12v DC) at Brown wire from FP Relay to pumps

if none, then check Red wire from EEC Power Relay

if none, check for voltage at W/LB and P/O @ EEC Power Relay

continue checking ckt

harbinger · May 13, 2015

Thanks for the reply, M. On closer inspection, it looks like the g111 ground was cut, not burned, so it must have been a PO thing.

I rechecked everything I already checked to see if I missed anything and found nothing new. All

The only thing that is funny is the FP relay ground. Connectivity light is on with the ignition off, and off with the ignition on.

I plugged my code reader up the other day too but it didn't ever look like there was a connection. I am thinking this has to be related.

harbinger · May 13, 2015

All wires coming off the starter solenoid have 12v

all wires after visible fusible links have 12v

G111 location, cut wire not burnt

G? behind right headlight, grounds show connectivity with ignition off

G801 (radiator support above left headlight) grounds showed connectivity with ignition off.

FP relay. have a new one I've been swapping in to troubleshoot.

harbinger · May 13, 2015

I have heard the large connector in this pic can corrode, goo way to check it? it goes to the negative cable.

harbinger · May 13, 2015

looking for PCM info now.

harbinger · May 13, 2015

Didn't find any good PCM info yet, but I did go check a few more things related to EEC. The EEC wires all check out and according to the writeup on testing the EEC it is all in working order.

http://www.thorssell.net/hbook/images/4hup96.gif

Using above link, I tried the EEC test again and test light came on when connected to #4, but no codes. Tested the ground at the STI (self test input) trigger and at the wire before it using a piercing probe and I have no ground there.

Now looking for info STI ground

miesk5 · May 13, 2015

yo,

run a ground wire from Scan Tool or from the DLC "Self Test Input" to Battery Negative Post

This is in case that "Signal Return Ground" circuit is damaged or a bad ground - see this depiction (click to Enlarge in a new window or tab):

by Jer

In you post #10 (large connector)

Stop at Lowe's or HD & look at the electrical section's Ground Clips

http://www.homedepot.com/p/Halex-14-12-Ground-Clips-10-Pack-26309/100154487

btw, any smoked capacitor odors around PCM?

harbinger · May 13, 2015

lol, not sure where the pcm is, it's been a few months sinc ethis first happened though so I don't think it would still smell. I should be able to see burn/char marks on the pcm if I open it? ok searched and found it. Should I pull it out and open it up? I did that on my honda a few years ago to verify a blown ecm

harbinger · May 13, 2015

as far as the STI goes, there isn't any connectivity there so jumping the wire just puts a neg charge on the STI but it is still broken somewhere so the code reader doesn't recognize that it is plugged in.

harbinger · May 13, 2015

headed to junk yard for side view mirror, will see about pulling wires from donor

harbinger · May 13, 2015

fact finding mission at the junk yard. Tracing the ground didn't really get me anywhere new. I guess I'll pull the pcm and see if I can get any info from that.

miesk5 · May 14, 2015

harbinger said:
lol, not sure where the pcm is, it's been a few months sinc ethis first happened though so I don't think it would still smell. I should be able to see burn/char marks on the pcm if I open it? ok searched and found it. Should I pull it out and open it up? I did that on my honda a few years ago to verify a blown ecm

[/quote

Yo,

PCM (aka EEC) is located behind driver side kick panel

EEC IV Location & Removal in an 87 by Bronco John Galt

My truck is an '87, and has an MAF adapter, but the principle is the same. In the first pic, the vacuum canister is attached (silver drum looking thing on the right hand side, lower right corner of the pic). There are just two bolts there, also 10mm IIRC, but if they aren't, just use the proper size socket.

http://i19.photobucket.com/albums/b191/joebeez/IMAG0854.jpg

Once that is out of your way, access to the front of the EEC is painless

http://i19.photobucket.com/albums/b191/joebeez/IMAG0857.jpg

http://i19.photobucket.com/albums/b191/joebeez/IMAG0870.jpg

Then you remove the driver side kick panel from in (side) the cab, and pull the EEC out. Later years come out in engine bay

http://i19.photobucket.com/albums/b191/joebeez/IMAG0878.jpg

NOTE!; I hope John Galt wrote this correctly; I never pulled a PCM from year; always saw it done in just 92-96 years and they came out thru engine bay

==

EEC Removal how to check capacitor leaks 92-96 by jowens

http://www.supermotors.net/registry/23246/82881

You can see some rust on the case.

Inside the case it was carnage.

The Inside of the EEC compartment was really corroded.

http://www.supermotors.net/getfile/1014310/fullsize/backup-eec2.jpg

=

Capacitor Repair in a 90 5.8

Source: by seedpress (dolittle) at Ford Bronco Zone Forums

http://broncozone.com/topic/20788-fuel-delivery-problem/

Capacitor Repair, Failures Due to Age; "...(A9x and same years ECM's) The patient in question is a remanufactured A9L unit. This ECM is the one from a little notch project I'm working on. It started giving some problems starting up, engine flooding, random hesitation, missing and stalls. I opened up the ECM (the car is running with a A9S unit) after the owner brought it for a checkup.What you see is the typical electrolytic capacitors leak, causing intermittent shorts/opens to the neighboring circuits/components and symptoms as the ones explained. Worst case scenarios with this type of failure, is a permanent no start and permanent damage to the PWB preventing it could be repaired. As soon as I replace the capacitors I'll update with the pictures showing the repairs. The following capacitor does not show any leakage problems however, it will also be replaced as a preventative measure..." Source: by Joel5.0 at

harbinger · May 14, 2015

Too hot in FL today to be working on an old greasy truck, I'm going to the beach. I'll update the thread on the PCM on Monday.

Thanks again, M

Reverse Continuity at fuel pump relay?

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