Yes...cycling the key from the Off to Run position triggers the computer (PCM) to turn on the fuel pump for one second. The PCM relay is pulled in, then the Fuel Pump Relay for one second.

When you crank the engine over the PIP signal, from the distributor, is sent to the TFI module (triggers coil spark) and the computer. The computer sees the first PIP pulse, then turns on the Fuel Pump Relay for one second. As more PIP pulses come in the computer timer is reset so the Fuel Pump relay stays energized as long as the engine is cranking or running.

If the inertia switch is tripped, further down stream in the circuit from the Fuel Pump Relay, the pump will never energize.

 

Well the good news is that my Bronco can handle the front wheel being jacked up to install a locking hub without setting off the inertia switch.

The bad news is that I still have a no start condition.

But I think you are right, it may be fuel pump related.

Any suggestions for diagnosing a no fuel condition in a stepwise fashion?

 

rla2005: Thanks!!! https://www.ford-trucks.com/forums/1...l#post15079234

 

Sorry I have not been around much lately to reply. Glad you found the problem.

 

rla2005: Your advice reset my mind to the basics: 1. spark, 2. fuel, 3. air. That was all that was needed to get my brain oriented on the proper path to diagnosing the problem. Then I was able to use the search function on this forum to drill down to testing each one of those basics. Thanks buddy!

 

Ok guys, after replacing the fuel pump (in Feb. 2015 I think?) the 1995 Bronco 5.8L has been running fine. Now I am stuck with a no start and the previously described flash code (my NGS Code scanner is not with me). This time I can definitely hear the fuel pump pumping up (humming for a second or two when key is turned to on). But although the engine turns over briskly and tries to catch, it won't really start.

This problem has been going on for about a week and a half. I have dealt with it by cycling the key quickly from off to on maybe three or four times then from off to start. Sometimes I don't even need to do that, it starts first try. Other times, I need to do it four or five times. After it starts, the vehicle runs flawlessly.

Now as I sit in the vehicle stuck in the Taco Bell parking lot, I have cycled the key in this manner maybe 15 times and it won't start.

It is not the inertia switch. It is not the fuel pump. Is it a bad relay? I know where the EEC-IV (i.e., PCM) is and I cleaned the pin contacts in Feb. 2015. Where is the TFI module? When I had this problem earlier in this year I thought maybe it was the three capacitors in the EEC-IV which I took out, opened, they weren't bulging so I didn't replace them because I don't trust my soldering skills with my soldering gun. Pictures here:

https://www.ford-trucks.com/forums/1...uestion-4.html

Someone mentioned a ground behind a headlight?

Any suggestions?

 

If the fuel pump cycles for 1-2 seconds it's not a fuel pump relay.

Since the vehicle will not start do you have spark?

Do the plugs look like they are gas fouled?

The TFI aka ICM is located on the driver side inner fender near the hood hinge, they rarely go bad on this vintage....

 

rla2005: Thanks! Looks like I will be riding with AAA and will check for spark when I get home.

In addition to your suggestions, my buddy told me to look for a small wire to the distributor. I think we have connectors. Should I look for that small wire and disconnect any connector in it and spray it clean with CRC contact cleaner?

 

Not sure what small wire your buddy is referring to.

A diagram of the ignition system on your truck:



Connector C178 connects the distributor to the PCM (computer). The Ignition Control Module (ICM) is remote mounted on the driver side inner fender near the hood hinge.

Removing the SPOUT plug effectively removes the computer from controlling the spark. The ICM will trigger on the raw PIP signal (sensor inside the distributor) instead of the buffered signal from the computer. So if there is no spark try removing the SPOUT then look for spark again.

 

To deepen the knowledge pool further, this version includes the Thomas Brother Maps-type grid reference to the Component Location View and, finally, here is a picture of the SPOUT, and then the SPOUT with the jumper removed.

 

rla2005: Starts right up with the SPOUT removed. So what does that mean? I have my suspicions, but I am looking for your (and others) input.

 

rla2005: I did not check for spark before I disconnected the SPOUT jumper. Because I am tired of having to remove a plug wire and then the spark plug and then reinsert the plug into the plug wire and then find a pair of insulated pliers to hold the electrode near a ground. So, what do you think of this device? Or do you have a suggestion for a better device?





http://www.ebay.com/itm/Cal-Van-Tools-64-High-Energy-Ignition-Tester-HEI-SPARK-PLUG-OUTPUT-USA-MADE-/201427365098?hash=item2ee601acea&item=201427365098&vxp=mtr

 

That spark tester will work fine. You can pick a similar one up at the local parts store too.

 

rla2005: So further up the thread, I mentioned that the engine repeatedly starts right up with the SPOUT removed.

So what does that mean?

Does it mean what I think it means?

 

Sorry, I missed that. If the engine starts with the SPOUT removed you either have a bad computer (most likely) or the SPOUT signal is grounded between the computer and the SPOUT connector. You would have a code for that.....

My money is on a bad computer. Try running the KOEO tests and CM display just to see what happens.