Fuel Pump Secondary Circuit fault

[chiefssc]

I have a 92 explorer that not keep running. It starts for about 2 seconds and then dies. I have run the codes and they tell me there is a fuel pump secondary circuit fault. Does anyone know, what is the secondary circuit? How do Ifix it? My book does not refer to a secondary circuit.

 

[chiefssc]

Sorry the Explorer is a 94 and the fuel pump seems to be working correctly

 

[MrShorty]

Which code was it, and was it a KOEO hard fault code or a CM code or both?

My code list doesn't list a primary and secondary circuit code, though I know there are code lists that do. You might look at a different code list to see a different code definition.

 

[chiefssc]

My code book is by INNOVA electronics Corp. It came with the code reader. It is a Ford OBD I reader. the code is 543. My Chiltons has the same code with the same description

 

[Spdrcer34]

There is a fuel pump shut off switch on the firewall, in the passenger side footwell area. As you are sitting in the passenger seat, slide the seat all the way back, and reach forward to the firewall with your LEFT hand...it's right there.

Ryan

 

[MrShorty]

The description I get from my list and BrooklynBay's list is "fuel pump monitor circuit shows no power". I'm not exactly sure where the fuel pump monitor tees off of the main circuit, but there's a wire between the fuel pump circuit and the PCM (pin 8???) that is how the computer monitors the fuel pump. If there's a break in that wire, the PCM won't see the voltage on the fuel pump circuit, but the pump will run just fine.

Another possibility is that you have a loose connection somewhere that the PCM can see the erratic voltage, but you can't.

Is this a KOEO 543 or a CM 543? A KOEO 543 would point more to the former scenario. A CM 543 (KOEO 111) could suggest the latter scenario.

 

[chiefssc]

The code is KOEO 543.

As I said before, I have a Chilton's manual. Is there a better publication or service manual that can be downloaded that more clearly describes the code causes and possible corrective actions.

Thank you all for your responses.

 

[BrooklynBay]

Welcome to this forum! # 17 in my list of useful threads has the list of codes Mr. Shorty described: http://www.explorerforum.com/forums/showthread.php?t=160035

 

[MrShorty]

The code is KOEO 543.

As I said before, I have a Chilton's manual. Is there a better publication or service manual that can be downloaded that more clearly describes the code causes and possible corrective actions.

Thank you all for your responses.

When it comes to code diagnosis, the best repair manuals are not "downloadable" The best ones are the professional manuals that will list the codes by year and engine, have complete wiring diagrams, and will include "circuit pinpoint tests" for each code. I have found that these are often available in the reference section of your local public library.

I have seen a downloadable version for a '95 Explorer (search for gtest.pdf) that comes from a russian site that can be a useful resource, and it will be pretty similar to your '94, but it won't be exact.

For this particular code, though, the wiring diagram in your Chilton's should be adequate.

 

[Spdrcer34]

the best repair manuals are not "downloadable"

....well they USED to be....

fordcds.com is being sued by Ford at this moment. It had the BIG factory manuals online, ready to download.....

Ryan

 

[chiefssc]

Well, I have replaced the fuel filter and I have checked the fuel pressure,
40 psi all the time. No bleeddown. There is fire at the plugs and compression is fine. The engine tries to start but will not keep running. I checked the air filter and it is clean and there is plenty of vacumn.
This is a real poser. Help please

 

[BrooklynBay]

Does it continue to run if you hold the accelerator pedal? If so, then the IAC might be at fault.

 

[chiefssc]

No it doesn't matter if I press on the throttle or leave it at idle.

 

[BrooklynBay]

Unplug the MAF, and see if you still have the same problem. The CEL should remain on while it's running.

 

[Shane91Explorer]

My 91 did the same thing...

I didn't have a check engine light, but it's not and OBD vehicle. However, your symptoms are identical. I replaced the fuel pump for no reason. I checked the inertia switch and it was good (the switch under the dash on the passenger side). It wound up being a short somewhere in the power to the fuel pump relay located under the hood near the air cleaner. I just ran a new wire and it's been great for about 7 years now.

Hope this helps.....

 

[chiefssc]

thank you all, I will try these ideas and let you know in a new thread. This one is getting a little long.
Chiefssc (Scott) Aztec New Mexico.

 

[BrooklynBay]

Include a link to this thread in your first post of the new thread so new people will know what has been done so far. You might get similar information in the second thread if people don't read the first thread.