Re: Ford auto mechanic?
 

No, not from my Windstar manual - that was sold many years ago on eBay after the Windstar met an early death.

I was looking at a wiring diagram for a 98-02 Crown Vic online somewhere (see below for a different example, but showing the same as what i remember). It is possible everything I wrote is incorrect, but unlikely. I think more likely I mis-interpreted the "Fuel Pump Prime Connector" purpose: It is not a bypass, but a way for the service technician to bypass the relay and prime the pump.

The Circuit numbers (87, 86, 85, 30) are standard nomenclature for the industry: 85 & 86 are coil, 30 is 'common', 87 is NO and 87A NC contacts.

I speculate that the fuel pressure is regulated in the fuel rail, mechanically. Often hard to get at or see, but look for the fuel rail, and a cylindrical hat-like object at/near one end. (I come to this conclusion based on their use of a mechanical relay: Hard on the relay contacts to try to do PWM pressure regulation that way).

I'm in the car industry, this matches how my company does fuel pumps, so it seems somewhat 'typical'.

==============
OK, we get power OUT of the relay, and this makes the pump run audibly. (Can't hear for sure with the engine running, but let's assume it does since 'prime' works OK).

This points to inadequate fuel volume delivery. This can be a bad (worn) pump, clogged pump input, clogged line from pump to fuel rail. Can't think of anything else it could be, based on what works so far.

Still have the old fuel filter? Cut it open and see if it's filthy or not. A positive answer helps condemn the pump, a negative answer doesn't help much at all. Some spoo in there is normal.

The service manual should have a pump delivery test. There usually is a service connector on the fuel rail, where you connect a hose and then run the pump for x seconds, measuring the volume of fuel it pumped. All the usual precautions apply; the hose helps make this safer but not entirely.

You use the "Fuel Pump Prime Connector" to run the pump (likely easier to get at than the relay). This is how I emptied the Windstar's fuel tank before I sold it for scrap (but I bridged the relay). Got out nearly 10 gallons, a significant fraction of the vehicle's value at the time.

Re: Ford auto mechanic?
 

Don,
I agree that the prime connector is to run the pump without running the vehicle. This is likely a test procedure to check the pump pressure.
Ether, The wire #37 is the wire I said runs across the engine compartment from the fuse block on the passenger side. You should be able to feel the relay engage when commanded or at least hear it. Since the supply line is "hot" all the time, the PCM supplies ground to turn on the relay. The interesting part is having the transmission switch on this part of the diagram. It makes you wonder if the transmission switch has something to do with the fuel pump relay circuit.

Re: Ford auto mechanic?
 

Thanks for all the help guys.

A small rodent had built a nest in the air intake box (upstream of the air filter fortunately: she hadn't chewed through the filter). This restricted the air flow which affected both the mass airflow sensor reading and the vacuum-controlled fuel rail pressure regulator.

Runs like a charm now.

.

Re: Ford auto mechanic?
 

You gotta be kidding.

In Europe, Stone Martens (a small rodent like a chipmunk or ferret) are a real problem; manufacturers offer an optional Marten Protection System that gently zaps any rodents trying to enter the engine compartment.

Ether, buy a new filter soon too. That one's too dirty now.

Re: Ford auto mechanic?
 

It's always something!

Re: Ford auto mechanic?
 

And if it's not one thing it's two.

EDIT:
Was following this thread, and I want to point out that it's a good example of how to ask a question on a public forum.

Re: Ford auto mechanic?
 

Always have to cover the basics. ;)

Glad you have it fixed and running! :)

Metal wire mesh is a great way to keep furry critters from making nests in parts of your car. It may be worth checking the exhaust system as well, especially if the car starts making really strange smells.

Re: Ford auto mechanic?
 

Just for the record I did check the air filter and air intake box when the problem first manifested. But the nest had apparently not yet been sucked up into the air filter box where it could easily be seen. I didn't pursue it any further since it didn't seem to fit the symptoms I was observing (engine always starting and idling smoothly, quietly, at correct speed for first few seconds), and therefore I directed my efforts toward other tests/inspections.

In hindsight, I can concoct reasons why the rodent nest could cause the problem, but nobody I spoke with prior to that suggested such a mechanism.

The following is probably a question that only a Ford engineer could answer, but I'll toss it out here just in case someone knows:

On the engine in question, does the PCM completely ignore the mass airflow sensor and fuel pressure for the first ~3 seconds after starting, and use some sensorless fuel and air metering strategy? Is that what would cause the engine to always start immediately and idle smoothly, quietly, and at the correct speed for the first ~3 seconds before beginning to misfire?

Re: Ford auto mechanic?
 

All this rodent-talk just reminded me of something that happened to my wife's car (Nissan Altima) about 6 years ago. The cabin fan started making a loud noise, like it was out of balance. I thought the bearings had worn out and it needed to be replaced.

When it worked its way to the top of my to-do list I started asking around and a mechanic friend said "Mouse. It happens all the time around here."

I pulled out the cabin air filter and there was a hole chewed through it. With a flashlight and a mirror with a long narrow handle I was able to look inside the squirrel cage, and there he was. He had been spun dry. I don't even want to think about where all the body juices went.

Long story short, I was able to retrieve him with a 18" long 3/8" flexible tube duct-taped to my shop vac.

I guess from now on "rodent" needs to be at the top of my checklist for car problems.

Re: Ford auto mechanic?
 

That is interesting that the nest got sucked up to the air filter. That's a new one on me too. In my (limited) rodent experience they go right for the airbox in the first place.

I have a theory that would explain your car's symptoms (and to off a speculative answer to your question):

In my stand-alone ECU I program a parameter called 'cranking pulse width' which varies based only upon engine coolant temperature, not MAF, MAP, or any other normal fuel-related sensor. Your engine starts just fine with this, and then, after a few moments of running, enough of the nest got sucked up against the air filter to 'suffocate' the engine and force it to stall.

The reduced flow should not have affected the functioning of the MAF sensor (it still would have measured the correct amount of air flow, pressure/temperature measurements are not required) nor the FPR (it still would have adjusted the fuel rail pressure to the proper level). But it would stop an adequate amount of air from reaching the engine.

Re: Ford auto mechanic?
 

I'm surprised that it was packed full enough for it to prevent the engine from idling. In my 2001 Grand Marquis I found quite a rat's nest in the air filter box during normal inspection during an oil change. My wife, who was the primary driver of it at the time had not noticed any reduction in performance (or at least not told me about it, which is very unlikely) and my rough guess is the about 75% of the filter was blocked by the insulation that was stuffed in there. Which reminds me I was in a bit of a hurry when I did the last oil change and I should go out and look at the filter. I really also need to inspect the air inlet in her current car since it has a "lifetime" filter that is a sealed box and I'm sure is rather expensive, since I doubt the aftermarket bothers with it.

Some vehicles (and the MegaSqirt which is what it sounds like James may be using) do have a strict cranking strategy that ignores many of the sensors. Some then have a transition strategy before they switch over to normal running strategy assuming the engine temp is high enough to not go into warm up enrichment mode. However from what I can tell the Ford EEC-IV and EEC-V use the MAF during cranking, as a dirty sensor is known to cause long crank times, particularly the colder it gets.

I'd say what was happening was similar to the classic dirty fuel filter problem. When the flow starts the loose stuff gets sucked (or pushed) up to the filter element causing the restriction and once the engine is shut off gravity pulls the debris back down and then it will flow enough to work until the process repeats itself.