What a pain in the Taurus

Michael Mobile Technician Utah Posted   Latest  
Case Study
2007 Ford Taurus SE 3.0L (U) 4-spd (4F50N)
Crank /Brief Start

Back in 1991 a movie came out called "Pure Luck". It was a story about an executives daughter that got lost in Mexico and the private eye assigned to find her is not having any success. Apparently this gal has bad luck. Martin Short plays the main character. He also has bad luck. I loved the movie. It feels like me sometimes. If you have a chance, watch the movie. It is pretty funny. I dedicate my next post to the spirit of the movie. You just can't pick them like this.

I was asked to program a replacement PCM in a 2007 Ford Taurus. I have done many before without issue. This one threw me a curve ball. The vehicle drove in the shop. It was treated with plugs and wires for a misfire and "chugging". The original PCM had a primary circuit failure code. That was the reason for the replacement. I came over Programmed the PCM and did the theft learn. After the replacement, I got a start / stall. I thought it was something to do with PATS so I went through the process again only to have the same result. I went through the PATS function carefully. There was no option for a parameter reset. Only erase and program keys. All three keys would behave the same. Start then stall. I fought it for quite a while. I watched scan data and read codes. No codes in PCM other than the expected P1000 code. Installing the original resulted in the same behavior.

It was getting real frustrating when a tech came out and gave me some good advice. He suggested we check the fuel and spark to see if one was dropping. I had tried to scope the injector but the vehicle did not run long enough to get a good trace. We hooked up old school with a noid light and a secondary spark tester. Neither signal stopped until the engine did. We then played with the fuel pump control module duty cycle. At some of the levels the fuel pump completely shut off. Odd indeed. We then added fuel to the intake. The vehicle ran as long as the fuel was being added. In the end we condemned the fuel pump and the fuel pump control module.

So here is the question. How is it that the fuel pump gave up the ghost when I was programming? (Pure Luck)

Theory... Ford changed strategy for FPCM. When the new program was put into the replacement PCM, it did in the dying pump and FPCM.


Anthony Technical Support Specialist
Anthony Default

Hi Mike: Since "It was treated with plugs and wires for a misfire and "chugging".", it is quite likely the pump was dead but the body hadn't dropped yet. When you got there, it fell down and went boom. Guido

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Eric Owner/Technician
Eric Default

I agree with Guido, the original complaint was due to a failing fuel pump. Were there any DTCs stored before the shop did their initial repair? I would bet there were mixture codes. That would be something I would ask and make a note of before programming. The times I've programmed for other shops I've always requested that information just in case something goes wrong.

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Albin Diagnostician
Albin Default

Everything has a time to die. You were at the right place at the right time. Over the years, I have had batteries, fuel pumps, ignition coils, injectors and many other things quit working when the vehicles were in my shop.

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Caleb Technician
Caleb Default

The pump was the original concern. Almost guarantee it.

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Allan Instructor
Allan Default

As Albin said, everything has a time to die. On my personal vehicle, drove it into the shop and changed the fuel filter. No start, fuel pump died. It was noisy so I wasn’t surprised. But explaining that to a customer who only wanted a fuel filter replaced. Let’s just say I’m glad it was my own truck. Especially since it had no issues other than being noisy.

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Michael Mobile Technician
Michael Default

A follow up to the story.... The tech called me this afternoon. The vehicle started with the old PCM but with a misfire. When I programmed the new one, the tech connected the MAF. Come to find out the MAF that they installed was defective. When they plugged it in, it disabled something. Once unplugged, the vehicle ran. The fuel pump issue is still up in the air. It was replaced before…

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Randy Diagnostician
Randy Default

You no what they say about new parts

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