1995 Ford Windstar Fuel pressure within spec range

Tiny
SEARCHERRR
  • MEMBER
  • 1995 FORD WINDSTAR
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 2,000 MILES
If a fuel pump is not meeting the pressure spec'ed by the OEM manual during operation is that pump ALWAYS considered bad and if not then why not?

This is a new engine and most all other wear parts are new as well. Pump and injectors are original. FORD says that spec fuel psi is 30 - 45 psi at idle and at 2500 rpms for 1 full minute.

Operating PSI at idle or 2500 rpms for 1 minute is 27 - 29 psi and never goes above 29 during operation. Revving cause it to stay/dip around 27 psi consistently.

FUEL PUMP BAD? If so then why do 2 of the shops I brought it to say NO? I'm very puzzled about this.

Recently I had the filter changed (only was 9000 miles old) on a hunch of bad gas (neighbor had some) and I was right. It was clogged. Key flick without eng on was only up to 12psi after depressurized system. Now since the filter was replaced it is 34 - 38 psi at 1st key flick no eng on though operating psi is still what I said above 27 - 28psi.

Lastly, I am getting 9 mpg in town and 17 hwy. Bad.

HELP me understand. Thank you so much.
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Friday, December 19th, 2008 AT 4:38 AM

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Tiny
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One thing to realize with fuel pumps and hydraulic sustems (any fluid) in general is that a pump creates flow. It is the restriction(s) in the plumbing which create pressure. So to answer your first question, if the fuel SYSTEM is not meeting PSI specs called for by the OEM, the pump may not be the problem.

Pumps go bad for two main reasons: Mechanically being worn out, or having "dead" areas where the motor brushes meet the poles. Usually, the latter happens more frequently and can be verified by hooking up the motor to a lab scope and viewing the amperage fluctuation as each brush passes over its corresponding pole. If one of the poles has a short or open circuit, the amperage will jump high or low for that instant the brush is in contact with that pole.

In an automobile, the pump creates fuel flow; it is (for the most part) the pressure regulator which creates and maintains the correct pressure. If you want to test the pump exclusively to see how much pressure it can develop, you would have to insert a fuel pressure gauge directly to the fuel line. Disconnect the fuel filter at the "in" port and hook up a fuel pressure gauge to the hose coming from the fuel tank. Or if you don't have the adapters, hook up your gauge to the "out" side of the fuel filter. Cycle the pump on for a few seconds and see what value you get. If your value is well above 45 PSI, you can figure the pump is in good mechanical condition. If there is an electrical problem with the brushes vs poles as decribed above, a lab scope will verify this.

Therefore, if your fuel pressure is low at the schrader valve with everything connected and the engine off, chances are the fuel pressure regulator is faulty. Hook up a vacuum pump to the regulator. No vacuum applied to the port simulates a high load, therefore should have higher pressure. Apply a vacuum to the regulator vacuum port and the fuel pressure should drop a few PSI.

Your 27 PSI, engine on, is low; likely due to a faulty fuel pressure regulator.

But before you run out and purchase a pressure regulator, just make sure the vacuum line attached to the regulator pulls a lot of air while the engine is running at idle. Pull the vacuum hose off while the engine is running; you should hear a strong hiss sound as air is rushing into the disconnected hose.

Your poor fuel economy may be due to this low pressure. If you have access to a OBD-II scanner which shows LongTermFuelTrim (LTFT) values, and if they are in the +15% range or more, the PCM is trying to compensate for the low pressure by increasing the injector pulse duration to maintain a proper air fuel mixture. However, there is still an imbalance in the fuel system, so haviing low fuel pressure and longer pulse duration is simply an effort on part of the PCM to keep the engine running at the correct air/fuel mixture. Your mileage will suffer as a result.
Furthermore regarding the bad fuel mileage, do you have an rotton-egg smell, or lots of soot at the tailpipe?

Automobiles rely on all systems being in balance with one another in order to run efficiently. I recommend getting the fuel pressure back to spec, then monitoring your LTFT, and recording your MPG to see if any progress is made.
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Friday, December 19th, 2008 AT 6:28 PM
Tiny
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Schrimpieman - I wanna thank you sincerely for your time and effort. You are the first person I've spoken to that has given such a detailed and new look on this and furthermore the first person to speak to the fuel pressure being low possibly being the issue with my bad MPG. Everyone else seemed to just disregard this information despite the spec PSI range which I verified in multiple places. I may make my first donation thanks to your reply. :)

NEWS: The FPR and Fuel filter are brand new (since the 1st post) and the injectors have been professionally cleaned at least 2x in the van's life in addition to 3 Berryman Chemtool cans in the tank too (over time). I have tested engine intake air vacuum before too and I remember seeing it was on the low end of the acceptable range on the gauge itself.

The fuel filter was only 9000 miles old, but it was DEFINITELY CLOGGED as 1st Key flick Eng Off fuel PSI went to 38 psi, whereas before with the old filter it was at 12psi on 1st key flick. Within those 9000 miles could this have ruined the fuel pump and/or clogged the sock?

Pressure is still 27 - 29psi at idle and at 2500rpms for 1 full minute. Usually though 27-28psi. I NEVER stall though. Never. And I did once have long dragging startups, but I think I resolved that by tightening the starter signal wire cause it stopped after that.

I smelled one day and its not rotten egg smelling and I see no soot either. If the soot would normally build up slowly likely I don't see it cause of the new exhaust. (IE: I replaced the cats and everything with a better flowing system for better MPG while towing; a while back I had thought the cats may be the culprit to this bad MPG.)

The reason I say I've never stalled is because every shop I talk to says I'd be stalling, bucking, or having starter trouble if the pump was bad, but I mean it cannot be simply that cut and dry. I mean I would figure you could have a WEAK pump that isn't quite OUT yet right? I would imagine most of the time tech's at the shops never see people with weak pumps for repairs cause their car still runs, but runs with crappy MPG and they never notice.

Let me ask a WILD question regarding the PCM - If the PCM were trying to overcompensate for the lack of pressure over a very long period of time. Say over 40k miles or something. Could this possibly burn the PCM out? I had to have mine replaced last year.
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Thursday, December 25th, 2008 AT 12:07 AM
Tiny
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Fuel pressure lower after new fuel pump installed

New fuel pump, new fuel sending unit, new fuel pressure regulator, new fuel filter

After new OEM fuel pump installed and tank cleaned of severe filth the operating pressure at idle is 27psi and 26 psi under load of 2000 RPMs or higher. New fuel filter only ran for 1 or 2 tanks under filthy gas tank and pressure on key flick comes up to 38 psi before starting engine. Spec operating range is 30 - 45psi.

Since the operating pressure has gone down since new fuel pump has been installed and given all the new fuel system items what could this mean is wrong? Why am I not seeing the spec range? And. There are no leaks either.
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Saturday, January 31st, 2009 AT 1:22 PM
Tiny
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Apologies for the delay in response.
After all your trouble, I'd suggest hooking up a different fuel pressure gauge to verify the one you have is providing accurate readings.

In a last ditch effort, since you mentioned a long time ago you had the PCM replaced, make sure it is flashed with the most recent Motorcraft/Ford software. Most likely, only your local dealer will be able to perform this service, unless you have a shop in the area which can specialize in this field.

Have you hooked up a good scanner and read the LTFT values (long term fuel trim)?
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Tuesday, February 10th, 2009 AT 7:14 PM
Tiny
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Schrimpieman,

The fuel pressure test gauge is brand new, so I don't doubt its working integrity.

Though curiously enough on the same day you replied to me I went to start the van up and the engine was struggling to stay running and shaking the van. I went outside and smelled fuel leaking out of the engine where the front exhaust manifold meets the front exhaust downpipe to the cat.

1. Doesn't this mean there is an exhaust leak there if I can see fuel literally spitting out of this area?

2. I have confirmed a stuck open injector right?

3. Can 96-98 Windstar 3.8L engine injectors be used in a 95 3.8L Windstar?

No worries, I immediately shut off the engine and now it sits waiting for new injectors.
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Thursday, February 19th, 2009 AT 12:44 AM
Tiny
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If I read your entry correctly, you saw fuel spitting out from the exhaust where the manifold meets the downpipe to the cat. Hmph. I'm not doubting you, but I am trying to envision this.

I'll answer your 3 questions to the best of my ability in the order you presented them.

1.) If you have an exhaust leak of the magnitude to have raw fuel spitting out, you'd definitely hear the exhaust rumble from that area. Otherwise, if the exhaust is quiet, the exhaust gasket is intact, and fuel could not be coming out.

2.) A stuck open injector: (And I am presuming the bank of cylinders you are talking about are nearest the radiator which makes the job easier). Try the following to confirm a stuck open injector. Remove the three spark plugs (cyl #'s 4-5-6). DISABLE THE IGNITION COIL PACK, and have an assistant crank the engine while you monitor the amount of fuel vapor emitted from the spark plug holes. If you have a stuck open injector, it will be constantly spraying fuel into the combustion chamber, and the piston will force the vapor out during its travel to TDC on the compression stroke. One of the spark plug holes will be emitting fuel vapor at a notable greater amount than the other two cylinders.

3.) You can go to any online car parts site such as partsamerica. Com or rockauto. Com or autozone. Com to compare part numbers per vehicle application. According to partsamerica, the part number for '95 Windstar fuel injector (Mfg. = BWD) is 49207. Compare that to the '98 Windstar fuel injector (Mfg. = BWD) is 57816. So I would say the answer is no. I suppose they have different physical or electrical characteristics.

Therefore, I present my commentary based on the conditions at hand:

Your poor fuel economy may be contributed to a bad fuel injector which was intermittently acting up during the past few months. It's just now that the fuel inj. Has called it quits and is failing completely. Good news for you because "ghosts" are difficult to track down and you can replace the part which has failed.
I doubt the single failed fuel inj was the main culprit to your low fuel pressure gauge readings. The low fuel pressure is still an open-ended question, but I feel the failed injector needs attention before trying to figure out the fuel pressure issue again. Fix first what you know for sure is wrong. Then the other stuff will iron itself out.
If you definitely do have a failed fuel injector, be sure to check your engine oil and/or change it. Fuel likely drained past the piston wall into the crank case and mixed in with the oil. Bad Bad. Change the oil immediately.

Check your catalytic converter(s) to make sure they are not burned out due to possible excessive fuel being dumped into the exhaust stream. Easiest way to do this is to hook up a scanner and monitor the O2 sensors voltage output.

When you get all your repairs done, I strongly suggest you have the vehicle hooked up to a scanner and monitor vitals such as Long Term Fuel Trim and the O2 sensors. Getting this data is very valuable to confirming the integrity of your repairs.

Finally, I can imagine all this is quite frustrating. Don't feel bad. We've all had engine symptoms which need lots of tinkering before we get it all right. I've surely had my share of experiences.
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Thursday, February 19th, 2009 AT 7:12 PM
Tiny
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Schrimpieman,

Thanks for the reply, especially about changing the oil. I would've never known or thought about that.

1. On my Windstar the exhaust manifold meets the exhaust downpipe-to-cat with the exhaust manifold having a tapered edge to fit against a metal seal when the flange is tightened. To my knowledge there's no gasket, but there my be gasket sealant used. Maybe its leaking. This work was done by the shop last time.

2. I'm not sure I need to run this test cause I don't know any other reason fuel would be shooting out of the front (yes, near radiator) exhaust pipe connection point. Though I will run the test anyway cause you took the time to write it out for me. :)

3. Thanks. Thats what I thought too.

4. Definite ghosts here. Been tracking this problem for 15 months. I believe this is the last thing that I'll need to fix to resolve the problem of awful fuel econ that I've been having.

5. The cats are new as of about 2000 miles ago. My original engine caused the rear cat to glow red (just enough to see "some red". Not bright red) so I thought wise to replace the cats. I hope I haven't ruined the new cats in 2000 miles.

6. Yes, frustrating. I've been pursuing this problem for about 16 months since a new engine installation along with many other replaced parts.

The Windstar (unlike many other cars and Fords) unfortunately does not have any fuel outputs to the PCM, so anything fuel related is calculated by the PCM via other sensor/input data. In other words the fuel stuff viewed from a scanner or datalogger tool is the PCM's best guess. O2's are reported for sure though. I have a OBDII to usb computer connector coming in the mail and I plan to datalog the van after I get things replaced.

Injectors are in the mail on the way. I'll post back once its done.
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Friday, February 20th, 2009 AT 4:18 AM

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