Runs great ...then seems to "fuel starve"!

99 3.8 Winny. Runs great at start-up, then after several miles begins to act as tho starving for fuel. No power. Won't pull hills well. Stopping, then restarting engine seems to reset "whatever" and the van runs great again ... for a while. The restarting has the same effect if van is still moving.

The problem got so severe that the engine would actually die ... only then threw codes P0171&4...nomally does not light off CEL.

What will reset in such a manner?

Since problem began, I have done following...all at the same time:
.Changed plugs.
.Removed and lubricated synchro shaft.
.Replaced DPFEgr sensor.
.Cleaned crank and cam sensors.
.Replaced fuel "regulator" and in-line filter.
.Replaced intake air filter.

This all seemed to make van run much better, but the problem is still there ... perhaps not as severe. Restarting will still cause a "reset"!

I'm thinking failing fuel pump ....(haven't had chance to measure pressure)?? Any better guesses? MAF? Ignition pack?

??

Have you tested fuel pressure?
A bad weak fuel pump can cause that. When it turns off, it rests and works better after.

I don't have other relevant ideas.

No,I haven't tested pressure yet ... sometimes it can take an hour or so for symptoms to occur. Long time to drive around with gauge in place.

I'm considering dumping and dropping tank ... just don't have anywhere to store 20+ gallons of fuel right now.

Lol, you can store them in my tank, I'm empty.

Seriously, it worths to drive many hours with the gauge taped outside windshield, rather than dumping the tank immediately.

The best way to test the pump is to to check also the direct fuel pressure from fuel pump (not just from fuel port).
A quick test is to block off the return line and see if fuel pressure comes up to 55-65 psi.
But do not run the pump more than few seconds for this test.

Well, I'm too desperate to be sensible ... already removed the pump. AutoZone has one they say.

This pump has over 200k on it ... so it doesn't owe me much!

200k miles for a Motorcraft pump! Impressive!

On more careful thinking, maybe it's more like 170k miles. The new one is going in!

Took all day long to finish job ... we'll see if it did any good.

Hi there! I would like to know if changing the fuel pump fixed you problem because my 2000 windstar makes the same. Also I would like to know if you could send me an image with the pinout of the MAF sensor as serge_saati pointed me to check the MAF sensor but he only has a pinout up to '98 windstars.

Here's a link to my thread:
http://www.automotiveforums.com/vbulletin/showthread.php?t=1023465

Thanks for your reply.

It will take me some time to get to your request ... as I am now travelling. Hopefully some else has that information.

It will take me some time to get to your request ... as I am now travelling. Hopefully some else has that information.

I have already found the diagram on the internet thanks anyway. I would really appreciate if you can post the result after changing the fuel pump as soon as you can.

Best regards...

Well, after driving 600 miles today... I am convinced the new fuel pump solved most of my symptoms. The car has plenty of power and accelerates well at all speeds. HOWEVER, after the first 200 miles, I picked up a CEL and the engine is not totally smooth especially around 70mph... I have not had a chance to have the code read. I was pretty beat when I was reinstalling the tank ... probably messed up a vent hose or something. May take a few days before I can have code read.

I see, well I guess I'll give it a try. Thanks for your time.

Good luck!

If I had had more time, I would have done some testing prior to beginning the work .. like already written, a pressure gauge taped to the windshield will give a lot of information.

If I had had more time, I would have done some testing prior to beginning the work .. like already written, a pressure gauge taped to the windshield will give a lot of information.

Yup, that's what I'm going to do tomorrow, I've been traveling and kinda busy too, but tomorrow I'll have free time so I'll start inspecting the fuel pressure and maybe I'll try cleaning the MAF and the intake boot. Thanks again.

Best regards...

HOWEVER, after the first 200 miles, I picked up a CEL and the engine is not totally smooth especially around 70mph... I have not had a chance to have the code read. I was pretty beat when I was reinstalling the tank ... probably messed up a vent hose or something. May take a few days before I can have code read.

An untightened vent hose wouldn't cause the engine to be not smooth. Maybe a clogged injector or something like that.

Of course, I'm guessing ... but if a EVAP issue caused a code, would that not prevent the PCM from fully "learning"?

We'll see when I finally get back home to my tools and familiar surroundings.

no, it should have learned before the code was dropped. Even if it was reseted, it will learn the rest.

Back in Georgia ... after 11980 mile test-drive around the country!

Engine performed well ... but the MIL light has been on all the way. I suspect the cable to the fuel pressure sensor got pinched, but won't be sure 'til the tank is dropped. (Great!! .. something to look forward to!). Anyways ... it's safe to say that fuel pressure was my original engine issue.

Good to hear. I see you do most of the helping around here.. it bothered me to think something had you stumped. :)

Thanks for the kudos ...

But I'm not sure I do most of the helping ... I just seem to have most all the problems!!!

For a little closure...

It turns out the replacement pump/sender assembly had a bad tank pressure sensor ... in fact, the terminals on the sensor were totally "open". A new assembly from AutoZone fixed the MIL.

No more mysterious stopping and power losses.