94 Taurus periodically won't start and/or stops

This is a periodic problem.

At times, the car won’t start at home first thing.
When being driven, it periodically dies and won’t restart. When it dies, it losses power & sputters like it is running out of fuel.

I even installed an electric fuel pressure gauge. On initial key turn & before start, pressure goes to 80# and then back to 45#. When running, it stays at 38-40#.

The wife says, when it dies while driving, the fuel pressure goes to zero with key still on.

I bought a real Taurus/Ford Shop Manual (not knock off). It was absolutely no help. There isn’t any fuel diagnostics in it.

I am so desperate, I’m just replacing things. Since it is only periodic, not much you can test in the middle of an intersection.

I have replaced the fuel pump & the fuel pressure control valve. It is still doing it!

I am trying to replace the fuel pump relay. I just went to the auto parts store and gave him all info. (94 Taurus with standard 3.0 – not SHO or Flexible Fuel). He gave me a standard relay module. I reading the manual that the fuel pump relay was in the Constant Control Module above the radiator. When I removed it, it is riveted. Do I drill out rivets to replace relay or is this just a wrong part and I have to replace the entire Constant Control Module.

I have a buddy that is a Lexus mechanic and he says it sounds like a bad crank sensor.
No RPM sensed, so fuel pump is turned off.
However, in reading the manual, crank & cam sensors are only on SHO’s and Flexible Fuel vehicles and not standard 3.0’s. Plus if it has one it is really hidden, because I can’t see it.

The wife is about to kill me. Plus it is dangerous, with car stopping in intersections or on freeway.

ANY HELP IS APPRECIATED.

One thing you could test when it dies and won't restart is for voltage to and from the fuel pump inertia switch in the trunk. If you don't have voltage to the inertia switch, then check for drive to the CCRM. You are correct, the fuel pump relay is integrated in the CCRM. The relay is not a user serviceable part, you would need to replace the entire CCRM.

Your factory service manual should give you a pinout for the CCRM, showing which wire is for the fuel pump relay coil.

Also, you don't mention if you replaced the fuel filter. If not, do so. That is a regular maintenance item and if by chance you got a big piece of something in the filter, it could be blocking the fuel flow as the fuel pressure changes. It's a long shot, but if the filter has been on there awhile, it's due to be changed anyway and is by far the least expensive potential fix at this point.

Also, what does your electric fuel pressure guage use for a signal? Have you tried a mechanical gauge on the fuel rail to see if it also shows zero PSI?

-Rod

Thanks for the reply.

As for the fuel filter, that was the first thing I replaced.

I also replaced it again, when I did the fuel pump about a month ago.
Plus the tank was clean when I repalced the pump.
The 1st guage I used was manual gauge. Pressures were about the same. I just put the electronic on to be able to monitor waht was going on while driving. I would have used a meachanical, but I don't like a fuel line in the inside of the car.

Is the any other device beside the enertia switch that can shut the pump off?
Is there any device that if RPM gets too low it shuts off the fuel pump?
Any high pressure switche?

I'm not aware of any switch that will shut off the pump if the pressure gets too high, nor am I aware of a low RPM switch.

If it were my car, I'd keep a multimeter with me and check the voltage out of the inertia switch when the car won't start as well as the fuel pump voltage out of the CCRM and the fuel pump relay drive into the CCRM and see where your likely issue lies.

-Rod