Ok, I am baffled! I have a 2003 F-250SD. Great truck, love her to death! There is one exception. She likes to shut off for no apparent reason. I travel at highway speeds, she shuts off. I travel in town, she shuts off. Cold or hot, cruse control or not, she likes to shut off. I can not duplicate the conditions that will make it shut off. Does not appear electrical, more like fuel. Filter has been replaced, plenty of pressure. Had it in our very trusted mechanic shop, and the only thing he could find is a slight fluctuation in the fuel pump relay, but he could not get it to duplicate the issue either. He stated the relay is on the back of and part of the fuse pannel.

Any ideas on why it would shut off? Again, not electrical, I do not get all the dash lights, just like there is immediate loss of fuel. I pull over, put her in park and she mostly starts right up.

I am basically loosing confidence in her, but I am very attached and do not want to replace the truck.

 

Welcome to FTE. Tell us a little more about your truck. We might have a better idea if we knew what motor you had. Also need to know if there have been any after market modifications done like a chip or tuner.

 

What engine are we dealing with here? 5.4, 6.8, 7.3, or 6.0? I have a 7.3 and the CPS is a known culprit for issues like what you describe. There is a Service Recall out for that so you can get a new one for free.

 

She has a 5.4. No modifications what so ever. I have had her for 4 years without any issues whatsoever.

 

Here is a link to the forum for 5.4 engines:

Modular V8 (4.6L, 5.4L) - Ford Truck Enthusiasts Forums

You might get the most help posting there, and also searching in that forum. Make sure to check your ground wires, fuses, etc and make sure everything is clean & tight.

 

It could be the fuel pump control module. Had a 3.0 24v Taurus that had symtems the same as yours. I was getting a P0191 code. On the Taurus the control module is part of the fuel pump. I replaced the fuel pump with a new Bosch unit and it's been good ever since. I think on our trucks that the module may be separate. I know it is on the 04 and newer f150's and it has been known to give problems due to corrosion. Check for codes. If it has P0191 or fuel pump related codes it's the fuel pump or fuel pump module most likely.

 

It sounds exactly like what my 3.8L Oldsmobile was doing a few years back (well, quite a few years back). No codes, no nothing...would just shut off, sometimes in the middle of traffic (very dangerous). At first, the shop could not identify the cause (no codes in the 'puter). He could not duplicate. I made him keep it until it finally did it for him, and he replaced the CPS (Camshift Position Sensor, as noted by papadelogan). Ran great for another 10 years!