Ford auto mechanic?
 

OK CD I need some help.

2001 Ford Crown Vic 4.6L V8

symptoms:

turn ignition key to "ON": I can hear fuel pump run for roughly 2 seconds

turn key to "START": engine starts immediately, runs fine for about 1 or 2 seconds, but then starts misfiring and stumbling and dies after about 3 to 5 seconds.

The above is repeatable. Happens every time.

There's a half a tank of fresh gas in the tank.

Since it was so easy to do, I installed a new fuel filter, but that didn't help.

Any help you can offer would be greatly appreciated.


Some questions:

1) I understand there's an inertia switch to shut off the fuel pump in case of rear-impact collision, and sometimes these switches go bad. But since I can hear the fuel pump when I turn the key to "ON", and since the engine starts fine, I assume this switch is not the problem?

2) How does the engine computer regulate fuel pressure in this vehicle? Does it read a fuel pressure sensor and pulse-width-modulate the fuel pump voltage accordingly? If that sensor fails, does it typically fail to a "high pressure reading" state that would cause the engine computer to leave the fuel pump off? Where is that sensor located on this vehicle and how difficult is it to replace?

3) If I can get my hands on a scan tool that can access live data, is there a PID for the above-mentioned fuel pressure sensor?

Re: Ford auto mechanic?
 

That engine is Coil-on-plug and aluminum heads right? I'd check to make sure none of the coils have burned up and also that you haven't blown a spark plug out of the head. I've seen both happen on a 2002 F-150 with the 4.6.

How many miles on it?

Crankshaft or camshaft position sensor could be a possibility as well. Do you get a check engine light while cranking?

I'd check/clean the Idle Air Control as well.

Re: Ford auto mechanic?
 

128000 miles. It's still a pup. Last year it ran like a champ. Then sat unused over the winter (but I put StaBil in the tank, and started and ran it for half an hour every week, and charged the battery once a month).

The engine starts every time, and idles smoothly, quietly, and at the correct speed every time. So I'm pretty sure it's not an ignition problem. And for sure no plugs blown out.

My working hypothesis is that the fuel pump runs only during the brief period for a couple of seconds after the key is turned from OFF to ON. Just enough to pressurize the system so the engine starts and idles for a couple of seconds. Then the pump doesn't run any more, and that's why it starts misfiring and stalls out.

Anybody have any insight into questions 1 2 3 ?

Re: Ford auto mechanic?
 

Once it starts idling have you tried maintaining a higher engine speed to see if it still dies? If that suddenly makes it maintain speed then you might just have a massive air intake leak.

Edit: I looked around a little and it appears that this is a fairly common issue on this car, they recommend checking the idle air control valve. then the fuel pump.

Re: Ford auto mechanic?
 

Hi Mike,

Cannot achieve/maintain higher speed with a higher throttle setting.

If it had a massive air intake leak, would it idle smoothly, quietly, and at the correct speed (as it does) ?

The idle air control valve controls the engine idle speed.

The engine idles smoothly, quietly, and at the correct speed. Symptoms do not appear consistent with a faulty idle air control valve.

Re: Ford auto mechanic?
 

if it is only idling smoothly for a second or two then yes it can still do that, but if you get more than four or five seconds before it starts dropping then it probably won't be the issue.

Re: Ford auto mechanic?
 

Cannot achieve/maintain higher speed with a higher throttle setting.

If the IAC were causing the problem, shouldn't I be able to press the throttle and hold engine speed at a higher value?

Re: Ford auto mechanic?
 

Anybody know how fuel pressure is regulated in this engine ?

Re: Ford auto mechanic?
 

Usually pressure is not modulated at all. The fuel pump is full on while a regulator regulates to the pressure (which is usually unchanging). This leads me to believe that it's not the fuel pump. The thing that would be change fuel to the engine is fuel injectors that are controlled by the ECU (engine Control Unit). If you're looking for data output from that, an OBD2 sensor is something that mechanics use to diagnose the car. Hope this helps

Re: Ford auto mechanic?
 

Ether,
With a car of your age, it is possible that the filter bag around the fuel pump is clogged or that the fuel pump is just weak. Most of the injected vehicles pump a rather high pressure to assist with the injection. A mechanic will likely do a fuel pressure delivery test to see if the pressure is reaching spec. According to one site your pressure should be in the 35 psi range. Many vehicles regulate the pressure by sensing pressure and turning the pump on or off. Some simply bypass the fuel back to the tank. It is common to only hear the pump during the first few seconds until everything is pressurized. At that point the pump is still running, it is just not making a lot of noise as it is running against pressure. The inertia switch seems to be a one time only device which would work or not. The fuel pressure is the first place to look but be very careful. Pressurized fuel rails is the most often cause of engine compartment fire. Follow the instructions carefully. You do not mention that your dash lights are indicating a problem so if that is the case, then a code might not be displayed on a monitor device. There is always the possibility that the wiring has gone bad with all of the salt and corrosion under the car in northern climes.
My pump makes more noise in the winter than summer.

Re: Ford auto mechanic?
 

See attachment. Is there a Ford mechanic or engineer out there in CD-land who can confirm the statement in the attachment?


My working hypothesis is that the fuel pump itself is good (because I can hear it turn on for a couple of seconds before I crank the engine... and the car always starts), but it is not being turned on once the car starts (and thus the engine gets starved for fuel, starts misfiring, and stalls).

I am looking for possible ways that a DIY-er like me can test that hypothesis.

My central problem is that I am unfamiliar with the design of this engine so it makes it difficult to draw conclusions from the data I already have. For example, consider question #1 in my original post. Can I rule out the inertia switch as a possible culprit because I can hear the fuel pump running before I crank the engine? In other words, is the circuit of the inertia switch such that if the switch were indeed tripped or faulty I would not hear the fuel pump come on under those conditions?

Re: Ford auto mechanic?
 

Hi Al,

Thanks for jumping in here.

This car spent its entire life in North Carolina and Florida until a couple of years ago when my mother stopped driving and gave the car to us. My daughters flew down to Florida and drove it back up here. I asked them to keep all their gas receipts, which they did. I was quite surprised (and pleased) to see that it got over 26 mpg on that road trip.

So being from the south, there's no rust and very little underbody or engine compartment corrosion.

If the pump is strong enough to supply the necessary flow and pressure to start the car and idle it smoothly for a few seconds, it's not clear to me why it wouldn't be able to keep the car idling.

So my working hypothesis is that the fuel pump itself is fine, but it's not being controlled properly once the engine is started.

In my previous post I attached a screenshot from the Chilton manual for this engine, indicating that fuel rail pressure is regulated by the engine control computer adjusting fuel pump speed (I assume by pulse-width-modulating the supply voltage).

That's why I asked question #3 in the original post. Does the engine computer for this engine have a parameter ID (PID) for the fuel rail pressure sensor? If so, I can borrow a scan tool and see what the fuel rail pressure sensor is doing.

Re: Ford auto mechanic?
 

My guy says the fuel pressure test is the telling diagnostic at this point. He asks if you depress the accelerator after it starts, will it continue to run? If you can keep it at 1500 to 2000 RPM then it points to something in the idle circuit. There is a pipe/hose that runs from the intake to the throttle body that feeds the MAS air flow sensor. That could be clogged or cracked or the sensor is defective. There is also a flap in the throttle body that supplies idle air that may have become dirty or stuck. It is able to be cleaned but it may take someone holding the throttle open while you use some carb cleaner on a brush to clean the plate and pivot. Don't spray into the throttle body. You may also have a IAC valve that is not working.
There is a wire that runs from the fuel pump relay on the front driver's side of the engine compartment across the front of the radiator and back into the passenger side of the car to the computer. This wire sometimes breaks,frays, goes intermittent.
Of course, if the pressure doesn't stay up during start and run, then it points to the fuel pump.

Re: Ford auto mechanic?
 

Here's the test sequence and results:


My working hypothesis is that the fuel pump itself is fine, but it's not being controlled properly once the engine is started. A fuel pressure test would only confirm what I am already pretty certain is true. It wouldn't help me find the cause. If I had an appropriate fuel pressure gauge and all the proper fittings I'd probably test it just to be sure... but in the meanwhile I'm exploring if there are other simpler things I can check -- things which might be interfering with the proper operation of the fuel pump once the engine has started.

I visited three auto parts stores and two auto shops this morning. There appears to be much confusion concerning fuel pump operation and fuel pressure regulation on this engine for this model year.

On the one hand:

Chilton's says there is no pressure regulator: The PCM (Powertrain Control Module aka engine computer) controls the speed of the fuel pump to regulate to the desired fuel pressure. To do that, I would assume the PCM would need a fuel rail pressure sensor, and sure enough Autozone's website shows a drawing of the top of the engine with a Fuel Rail Pressure Sensor (FRPS).

On the other hand:

None of the auto parts stores (including the afore-mentioned Autozone!) could find a FRPS listed for this engine. They all said the engine uses a FPR (Fuel Pressure Regulator). The auto shops I visited thought the engine has a pressure regulator. One even gave me a quote to replace it.

There is a large hard plastic cowling covering the top of the engine, hiding from view the area I would otherwise simply look at to resolve this question, and it is securely fastened with a weird fastener whose removal process I have yet to figure out.

Later today I will take a photo and post it here, maybe someone has seen something like it.

Re: Ford auto mechanic?
 

Ether,
My guy also said there is a fuel rail regulator rather than direct control of the fuel pump. Again the fuel pressure test would show if that was at fault as well. I have been told that more often than not, the pump gives up all at once. Since the engine bogs down and quits with either the pedal depressed or simply idling, we can rule out idle circuit troubles I think. Still points to fuel pressure/delivery. My guy is not a big fan of Stabil for cars BTW.
The MAS airflow still could be an issue and in some cars, you can disconnect it to get the engine running and some you can't. Be warned that there are two numbers for the same engine in that line. When you order parts you need to know that number or the VIN number to get the right parts.

Re: Ford auto mechanic?
 

It has a fuel pressure regulator. AND it has a fuel pressure sensor.
Rockauto.com lists both parts: Fuel Injection Pressure Regulator and Fuel Pressure sensor.

If the crash inertia switch were triggered the pump would not turn on at all.
See: http://troubleshootmyvehicle.com/for...rt-condition-2

Seeing as you seem fairly convinced it's a fueling issue I would recommend getting a voltmeter on the fuel pump or the fuel pump harness while the engine is started and then running. This will be most instructive and could indicate a bad fuel pump relay, relay fuse, fuel pump fuss, bad wiring, etc. Note: eye-balling fuses won't indicate if they're failed due to hairline cracking, which does happen. I believe this wiring may be accessed fairly easily in the trunk. I personally dislike using fuel pressure gauges in general because of the risk of leaking fuel.

There are a few other things to check on a car of that age that should take a total of 20 minutes:
-Check all vacuum lines (dry rotting, cracks, leaks)
-Clean the MAF (mass air flow) sensor (a dirty MAF is a sad MAF)
-Clean IAC (these like to get plugged with build-up from the PCV system)
-Check the air filter

FWIW my first car was a 2000 Crown Vic (police interceptor) and these days I maintain four cars and work on a couple race cars. While I'm no Ford engineer I have turned a wrench or two :)

Re: Ford auto mechanic?
 

AIUI, the 8th digit of the VIN is either a "9" or a "W".

On my Vic it's a W. Anybody know what the differences are?

Re: Ford auto mechanic?
 

I've had excellent results using StaBil in small engines (chainsaw, go-kart, ATV, yard tractors, walk-behind brush mower, etc) but never used it before in a car.

What does he not like about StaBil in a car, and what does he recommend instead?

Re: Ford auto mechanic?
 

^This is an excellent idea.

Does anybody know where I can find a detailed electrical schematic?


ditto that. gasoline is scary stuff.

Re: Ford auto mechanic?
 

FSM (factory service manual) is your best bet. I like to get digital copies and have a laptop/tablet in the garage.

You could register with Autozone to get access to repair/service manuals, here.

There are, of course, numerous other sources.

IMO Haynes and similar are about useless except for listing torque specifications, so I do not think you should bother with one of those.

A google image search yields some interesting results, but nothing of great resolution...

Re: Ford auto mechanic?
 

9 indicates a 'natural gas' burning CV, W indicates SFI (burns gasoline, 99%+ of CVs)

Re: Ford auto mechanic?
 

I couldn't find any electrical schematics for the fuel pump circuitry there. Maybe I'm looking in the wrong place.

Re: Ford auto mechanic?
 

Is this the official service manual published by Ford?

Re: Ford auto mechanic?
 

I checked last night when I had a chance and couldn't find anything either. Plenty of schematics, but not of the fuel pump wiring.

I can't vouch for this particular manual, but I've had good luck with similar purchases.

You can always get the hard-copy version, which is clearly marked 'Ford Motor Company': http://www.ebay.com/itm/like/310968012052?lpid=82

Re: Ford auto mechanic?
 

I went ahead and ordered it last night. We'll see.

Meanwhile, while I'm waiting for delivery, does anyone know where I might find schematic of fuel pump wiring? I've tried the Chilton manual (database available through our library) but no cigar.

Re: Ford auto mechanic?
 

Ether,

From your description, we know several things are good.

But we don't know if the fuel pump relay is good, or if the system controlling the relay is good, or if the pump is delivering sufficient volume.

The Prime function (2-second run you hear before crank) bypasses the fuel pump relay.

The relay NO contact ("87") is actuated by the PCM (powertrain control module) during start and run; verify pump gets power while cranking. You can also jumper across relay - Terminals "30" (+12V in) and "87" (not "87A"). Temporarily, of course, but OK for many minutes.

PCM uses several inputs to decide if pump runs: If engine speed <~400 RPM it shuts off, for example. PCM grounds terminal "85" to close relay, you should have +12V at terminal "86" all the time (or at least with ignition on).


The genuine Ford manual will have both diagnostic trees you can follow and a basic explanation of how it works. At least my 98 Windstar manual did. Note that the Electrical Troubleshooting Manual (wiring diagrams) was a separate book for my Windstar.

So dd that check and we'll see what to do next based on the result.

Re: Ford auto mechanic?
 

Thanks for the post Don. I'll follow up on it in more detail a bit later today. In the meantime, I've got a few questions:

Is there a physically separate relay component for turning on the pump for the prime function? Or are there 2 relays in one package: one for prime and one for when the engine is running?

Is this specifically for the 2001 Crown Vic 4.6L V8 -W? May I ask where you got this info from and if it's available somewhere online?

Will do!

If the previous test indicates I'm not getting voltage out of the relay I may try this. But here's my concern: It's still not clear how the fuel pressure is regulated on this engine. Some sources say there's a separate regulator, but some other sources say that the PCM regulates pressure by varying the fuel pump speed. If there's a separate regulator I can see where it would be OK to jumper the relay. But if the PCM is regulating pressure by turning the fuel pump on and off it's not clear to me it would be OK to override this function.

Again, this is exactly the kind of info I am looking for. Where are you getting this from? Is it from your Windstar manual?

Re: Ford auto mechanic?
 

Just because a picture is worth some number of words;

http://www.supermotors.net/registry/media/175395_1

and a connector diagram;

http://www.supermotors.net/registry/media/175387_1

These both appear to be for a 2000, but from what I can tell it should still be applicable.

Also, I came across this diagram of a CV fuel pump wiring. It's not clear what year it is for but I expect the mid 90's to 2003 were all pretty similar. It does include the 'prime connector', which is just an easier way of bypassing the relay. If it's present on yours it might be a good place to watch the relays behavior, and an easier way to bypass it temporarily.

Incidentally, the electrical wiring diagrams would be found in a specific Ford manual. In this case, FCS-12118-01 (where the last two digits appear to be a year code, so 01 for 2001). They're out there in printed form, though I have no idea if the electronic manual you ordered will have the same information or not.

Good Luck!

Re: Ford auto mechanic?
 

Don, did the above info come from your 98 Windstar manual?

Re: Ford auto mechanic?
 

Are you sure of this?

I just ran a test:

key OFF: Pin87 reads zero volts

key ON: Pin87 reads 12 volts for 2 seconds while I hear fuel pump running, then goes back to zero when pump stops.

turn key to START: engine starts, Pin87 reads 14 volts, stays there. I turn key off when engine starts misfiring.

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.