So Im still at it. Here is an update:
replaced the following itesm

1) Solenoid
2) Neutral Safety Switch - The truck will now start to crank but not start
3) Battery - Only had 350 cold crank amps
4) check PSI - 35-40 psi range
5) check codes:
KOER Code = 44 Thermactor Air Injection system inoperative (Right side).
KOEO Code = Got a 10. Not sure if they one is correct or even a real code
6) Changed the fuel filter

Odd thing is now the bronco will run just fine when the code reader is plugged in. As soon as I unplug it or turn the code reader off the truck dies and will not start back up. I plug the reader back in or turn the power on if starts right up.

Not really sure whats going on?
Thanks for the help

 

You should probably re-run the test....None of the codes should have a 'zero' in them.

 

Yeah I am sure I need to rerun the KOEO tests, but I am still wondering why the truck will run/start fine when the code reader is plugged in and the dies when i unplug it or power it off.

Could the reader be completing some function that is faulty for the truck. I just don't get that is part.

 

I hope you all don't mind me giving this a little bump. I am still stumped as to why the truck would only start when my code reader is plugged in and powered on.

I read in another thread the maybe a bad ground to the start created the same symptoms that I am seeing. Do you the reader by provide a better ground or something. I am just guess I really have no idea.

Thanks for the help.

 

Maybe I missed something in a previous post but will it crank without the reader in place? The reader should be bypassing the fuel pump relay circuit when its plugged in. other than that, there is no connection to anything but the ECM with the reader connected/on.

 

It will crank but not turn over unless the reader is in place and running. So it sounds like the next step may be to replace the fuel pump relay circuit next?

 

If I missed it sorry, but did you push that little button at the fuel pump shutoff by your left foot while sitting in the truck? Shoulda threw a code though if it flipped. It's a breaker put in place for when you get in an accident, it's easy to accidently trip while troubleshooting stuff.

My thought process would be this.. the MLPS was the problem, in the process of troubleshooting and trying to fix it in other areas, you have forgotten to plug something back in, somethign isn't tight, etc. I'd really look at that fuel pump shutoff, dunno how many times I've accidently flipped that breaker while doing other work.

 

Thanks for more info. I guess my only question is doesn't the fuel pump safety switch kill the power to to the pump to keep it from running? Would the code reader bypass the safety witch? I would think that if the switch is flipped even with the reader plugged in no power would be getting to that switch.

I guess my next steps are switch out the fuel pump relay and then if that does not work i will move on to the safety switch.

Thanks you all again for the ideas.

 

I'd say try the switch first, as its free and readily available.

 

So this is what I did today:

1)Replaced the fuel pump relay part number E3TB-9345-A2A
2)Tried to start the truck without the reader plugged in and it still would not work
3)Took out the fuel pump relay with the reader plugged in and the truck would not start. I wonder if the reader is really taking over the function of the relay
4) just for fun I took out the other relay in the same area part number e7ae9341aa and the truck would not start with or without the reader plugged in.
5) Check the Inertia Fuel Shutoff switch and the button was down and the marble was in the correct spot. Just to see the if the reader was taking over the Inertia Fuel Shutoff function I tried to start the truck without it plugged in and and the truck would not start. This leads me to think that its working correctly.

So what I have found out (or at least I think I found out) is that the fuel pump relay switch is working correct and the Inertia Fuel Shutoff switch is working correctly.

Any ideas what I should try next?

 

one of the connections in the test plug grounds a circuit so that the fuel pump keeps running, as a test/troubleshooting procedure. It sounds like this might be going on, will the truck start and run with a shot of ether in the air box and the code reader not plugged in?

 

I have not used either yet...but I can give it a try. So I was also thinking that my be my ground from the fuel pump is bad? Could that be an issue, and if so does anybody have an image of where the ground wire might be. I'm not sure what it would look like.

 

I think your fuel pump ground is fine. The fact that it will run with the tester IN, and gk50's comment on tester ground is a clue.

I looked in my 1994 EVTM, although it is 6 years newer than yours, it shows that a wire runs from one side of the Fuel Pump Relay's coil, to the test connector, and to Pin 22 of the PCM. The PCM grounds this pin internally to energize the Fuel Pump Relay.

So if the tester grounds this line, like gk50 says, that will energize the Fuel Pump Relay. So that checks out the relay, the fuel pump, inertia switch etc.
That leaves the line from Pin 22 of the PCM to the relay socket, or to the test connector, however they ran the wire. I'm thinking open wire, dirty/open PCM connector contact for Pin 22, or a PCM with an internal problem that it can't ground pin 22 anymore.

Since that circuit has continuity from the test connector to the relay, you could check for continuity from whatever pin of the test connector to Pin 22 of the PCM socket with PCM unplugged and ignition OFF.

The book I have does NOT show a connector pinout of the test connector, however, maybe you could find that on ford fuel injection .com to find which test connector pin is for the fuel pump ON.

My book shows that circuit as having a Light Blue wire with an Orange stripe. May or may not be the same as your years. And wire colors can darken with age.

 

Thanks Torky2. So how do I test this without unwrapping all the wires from the fuel pump relay or the test connector to the PCM. Is there an easy way to determine if this is the issues? When looking under the hood it looks like a lot of wires and I don't want to get it turned into a rats nest if I can help it.

thanks

 

I don't advocate unwrapping a harness to test this.

Here: Ford Fuel Injection » How To Run a Self-Test
is a link to the pinout of the Self Test Connector. Scroll down it and you will find which pin on it is the Fuel Pump pin.

Then look at this: Ford Fuel Injection » Wiring Harnesses
scroll down to the bottom-most wiring diagram, which is titled: Fuel Injection Harness Power circuit. Though it is for a Mustang, you can see the idea. Note the wiring from the Self Test Connector to pin 22 of the PCM (EEC), it also goes to one side of the Fuel Pump Relay's energizing coil terminal.
Just for reference, in a Bronco the OTHER SIDE of the relay's coil get's battery via ignition switch to fuse then through the PCM Power relay to the Fuel Pump Relay's coil.

Since you know the circuit is good from the Self Test Connector's FP pin to the Fuel Pump Relay's coil, you need to verify whether you have continuity from that FP pin on the Self Test Connector on through the PCM's pin 22.

So you will have to unplug the PCM. Look closely at both the PCM's pin 22, and the corresponding pin 22 in the harness connector for corrosion, burnout, whatever. Then ohm out the connection (with ignition OFF, of course) from that FP pin on the Self Test Connector to the PCM Harness pin 22 to check that wire.

Here is a page that shows the pinout of truck computers:
Ford Fuel Injection
Look for Bronco and your year and engine. It shows that PCM pin 22 is the pin that the PCM grounds to turn on the Fuel Pump. It says "FPR" for fuel pump relay, because that is what it controls.