It just died

[Joplin]

As requested by miesk5.

My 94 Bronco just stopped running, thank god it was in my driveway. Fuel pump not making a sound. Check all relays and fuses and they are good. I can jump out the contacts and the pump starts working. Have power to one side of the coil of the relay but it want work. Please help. Oh I have check the fuel shut off switch, not tripped.

I did pull and test all relays. They were good, but I will flip the horn relay with the fuel pump relay when I get home tonight anyway. Thanks again miesk5 for the info and I will let you know what happens. /emoticons/[email protected] 2x" width="20" height="20" />

1/3/11- I swaped the relays with no luck. All relays are good and I have hot "+" on one side of the coil, in the power box. No "-" I traced back threw all the tape to the EEC test plug. Good to there, then it goes to a block that connects threw firewall. WOW!!! Does anybody know where the - goes???

 

[BroncoJoe19]

The fuel pump relay has two sources of power. There is one that is always hot from a fuesable link (that is on the switched side, and supplies power to the pump when the switch is closed). That is the side of the relay socket that you are jumpering.

The other source of power is from the EEC relay. That goes to the coil side of the relay. You say that you have power there. IF the relay is good, and the other side of the coil is grounded, that will energize the coil, which will close the switch, which will send power to the pump.

Therefore the ground side of the relay coil is not being grounded. Possibilites... bad ground, crappy connection, broken wire, bad ground to the PCM, bad PCM.

IF you ground the fuel pump test pin in the self test connector to a known good ground, and the relay doesn't close, then the problem is between the self test connector and the relay, otherwise it is between the self test connector, the PCM and or it's ground.

 

[miesk5]

yo Joplin,

Good that you began a new thread instead of having further discussions on your issue in the other post @ http://broncozone.com/topic/22507-problems-starting/page__p__117503#entry117503

Here is my reply tWELCOME!

For the heck of it; eziest check first;

in Power Distribution Box

swap your Horn relay (assuming Horn Honks)

w/PCM Power Relay (bottom relay)

Ck for Corrosion in Socket(s)

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."

Wiring Diagram in a 94 from EVTM, partial (at FP relay)



Source: by Mikey350 at SuperMotors.net

Ck DG/Y

 

[Joplin]

Okay day 3 of pulling my hair out...I ran a jumper from the EEC TEST to the frame. When I turn the ignition on the pumps runs, does not stop after a few seconds. Tried to crank up engine, no luck. Would the pump going bad cause this situation???

I do not understand how the pump works and no crank... I have fuel in my tank.

 

[Joplin]

Would the filter being clouded cause this, like some safety thing. I just don't know why the damn thing was running fine and I put it in reverse and it stopped dead. Errrrrrrrr... Anyone need a bronco?.!,?!,?!

 

[Joplin]

I just check the spark plug wires, had a hunch. No spark, the rotor, no spark. It's pointing to the coil. Would this cause my fuel pump not to work???

 

[Krafty]

the fuel and ignition systems are not connected in any way, one going bad would not affect the other.

for the ignition problem run through the basic tests, the haynes manual covering 94 bronco and f series has an in depth ignition diagnostic procedure.

test for spark on wire one, then test for spark on wire from coil, if they're both dead check for your 12v power at the coil. if you have power at the one wire on the coil, with a test light check for bright flashes from the "TACH" or (-) wire when turning engine over at start.

if you have bright flashes then look at the haynes book about testing the coil.

it also never hurts to do new plugs, wires, cap and rotor, as well as fuel filter and air filter when running into these problems.

 

[BroncoJoe19]

Joplin,

You may have an intermittantly bad EEC relay.

When it fails to connect, the PCM/EEC will not get power. WIthout power... you'll get no spark, and the fuel pump relay will not get a grounding signal for it to energise (therefore no fuel pump action).

How to check a relay

http://www.fordforumsonline.com/forum/electrical-lighting/144-howto-check-relay.html

 

[miesk5]

yo,

Back to Ignition & Fuel again;

MIESK5 NOTE; from Ford EVTM; The Control Module (PCM) runs the pump{s} for one second when it receives an ignition-on signal. It also runs the pumps as long as it receives a PIP signal from the Hall-effect devices, it continues pump operation even after the key is released from START. If the PIP signals fall below 120RPM, the control module cuts off the signal to the fuel pump relay. The pump will also run when the terminals of the fuel pump test connector are jumped. the Control module signals the pump when it receives a CRANK signal, and when the Control module gets PIP signals that the engine is running. the pump does not run if the PIP indicates the engine is not running even with ignition ON {except for that first one second}.

No Start Troubleshooting but Starter Cranks Engine in 4.9, 5.0, or 5.8L; "....TIP 1: Since a lot of folks confuse a No Crank Condition with a No Start Condition... I'll clear it up right now: In a No Start Condition means your vehicle's Starter Motor is cranking the Engine but the Engine is not starting. In a No Crank Condition, the Engine is not cranking when you turn the key to crank the Engine. This article only deals with a No Start Condition..." read more

Source: by easyautodiagnostics.com @ http://troubleshootmyvehicle.com/ford_no_start_4.9L_5.0L_5.8L/diagnose_no_start_1.php

an excerpt;

"Test the Ignition Coil.

Check for Spark directly on the Ignition Coil tower.

The Distributor Cap and Rotor can go BAD and not deliver the Spark that the Ignition Coil is delivering to them... so testing for Spark directly on the Ignition Coil is the best way to check this.

If you do get Spark from the Ignition Coil's tower, then now you know that the Distributor Cap and Rotor are fried and need to be replaced...

◦The PIP Signal is also used by the PCM to start injecting Fuel into the Cylinders

here are a few other symptoms you'll see along with No Spark:

None of the Spark Plugs will fire Spark.

The Fuel Pump will still work.

The PCM will still activate the Fuel Injectors.

 

[Joplin]

I checked the coil, no spark. Replaced with new, still no spark. I think it is the Powertrain Control Module. Does this sound right??? I called around for priceing. Everyone told me it is a factory item. Does this mean big bucks....

 

[BroncoJoe19]

Joplin,

NEW PCM... yes relatively big bucks, but not a killer. While a bad PCM is a possibility, there are a couple of virtually FREE possibilities.

The Free-ist possibility is a bad ground to the PCM. G104 in the diagram linked to above by our friend miesk5. It is near the firewall, driver's side hood hinge. Clean it.

The next to free possibility is a faulty EEC Relay. Check it, or swap it around.

Other free possibilities include crappy connections in a number of places. Most likely at the relays, or possibily at the PCM itself. That big connector that you mentioned earlier that goes to the firewall is the PCM connector. You can pull that, check for corrosion, or water intrusion, and replace it. That's a 10mm bolt that holds the connector in place.

There is another possibility, and that is the ground wire G104 is broken within its insulation, and makes intermittant contact. That however would be low on my list of suspicions. You could check for continuity to pin 20 inside the connector if you pull the connector.

 

[miesk5]

yo;

for the EEC PIN 20 that buddy Broncojoe mentioned;

Here is the EEC Connector diagram by Ryan M

http://oldfuelinjection.com/images/eec04.gif

and his PIC Chart that sows PIN 20 is Ground

http://web.archive.org/web/20110414070047/http://fordfuelinjection.com/truckpinouts.html

slow to Load since I retrieved it from www heaven

For the relays, I think I mentioned that there may be corrosion in socket... and some have a broken wire @ socket.. may be due to prev owner or shop MAN HAND (a Seinfeld/Martha Stewart joke) bunging when replacing plugs, exh manifold, etc.

 

[Joplin]

Thanks for all the help from everyone by the way...

Cleaned and tested ground from PCM connector to frame ground near hood hinge, good.

Opened the PCM connector, wow what a long bolt. Some corrosion not bad, cleaned and replaced.

While connector off checked from relay pump coil ground to connector also good, but from ground on coil relay not good to frame ground near good hinge. "if that makes sense"

Oh even checked ground to PCM module also good.

Still no pump or spark action.!?!.?!!!???

 

[Joplin]

Went to local "pull a part" got a PCM module just for the heck of it and swaped it. Still no spark, no start. WOW do not under stand.

 

[Joplin]

How can I pulls codes with out a OBD???

 

[miesk5]

yo,

Pull codes with a a Self Test for Diagnostic Trouble Codes (DTC)s by my pal, BroncoJoe19

The engine temperature must be greater than 50° F for the Key On Engine Off (KOEO) Self-Test

Make sure A/C is off and transmission is in Park (automatic) or in Neutral for a Manual & release clutch.

Do Key On Engine Off (KOEO) portion

Look Codes up in my broncolinks.com site using the new Search function.

And Post em here

Back to the wiring diagram I posed previously by Mikey



With Key On;

Tell us what wires have 12 v DC or more

Since you prev. wrote; "Have power to one side of the coil of the relay but it want work" I assume you meant that red wire has 12v and LB/O wire is ground from PCM

On main contact side of relay (power to pump); should have 12v always from Y wire

DG/Y wire should have 12 v too.

At interia switch ck for 12v at DG/Y side and other side too.

etc.

 

[BroncoJoe19]

miesk5,

I was hoping that you were watching and would post that pin-out for the PCM.

Thanks! /emoticons/[email protected] 2x" width="20" height="20" />

How to scan FORD on board Diagnostic Trouble Codes (DTCs) in your driveway

http://broncozone.com/forums/index.php?s=&showtopic=14269&view=findpost&p=74587

 

[BroncoJoe19]

Thanks for all the help from everyone by the way...

Cleaned and tested ground from PCM connector to frame ground near hood hinge, good.

Opened the PCM connector, wow what a long bolt. Some corrosion not bad, cleaned and replaced.

While connector off checked from relay pump coil ground to connector also good, but from ground on coil relay not good to frame ground near good hinge. "if that makes sense"

Oh even checked ground to PCM module also good.

Still no pump or spark action.!?!.?!!!???

Yes that does make sense. The PCM makes the connection internally. But only when initially powered on, and while it recieves a PIP signal.

I'm scratching my head a little bit here. So I am going to go to basics. I'm thinking that when you have no spark and no fuel pumping, that your EEC relay may have dropped out.

Are your battery cables clean and tight at both ends?

Ground 100 for the EEC relay is at either the left or right upper radiator support, check and clean them both. (I think it is the one on the passenger side).

What is your battery voltage? If it is too low, and then drops while cranking the EEC relay may drop out, and then you'll have no spark or start.

Did you ever check your fuel pressure? That would be a good idea.

You stated initially that if you jumper the relay it'll start. Is that still the case? And which relay are you referring to?

 

[Joplin]

Attached is photo with notes