fuel pressure issues 2001 SPORT TRAC 4.0

10

Asked by Dec 28, 2014 at 11:15 PM about the 2001 Ford Explorer Sport Trac 4WD Crew Cab

Question type: Maintenance & Repair

ok, here is my problem..my truck had low fuel pressure ie. 25lbs at idle.. i replaced the
fuel pump assembly suspecting pressure regulator was bad. which it was..my preasure
after replacement was 70lbs which i have been told was where it should be..my live
scantool data has fuel trims within normal range after replacement..all good right!! well
i have had to replace the fuel pump assembly twice within the last mo..pressure starts
off fine, then about 2-3 weeks later dropps down to the 20's..LTFT runs up to 25 and
the truck codes lean..i have been purchasing my parts from AUTO ZONE and getting
replacement pumps from them under warranty replacement..IS THERE ANNOTHER
PROBLEM THAT I SHOULD BE LOOKING AT THAT COULD CAUSE FUEL
PRESSURE FAILURE? ANY HELP PLEASE?..THANX

13 Answers

18,485

consider the regulator malfunction to release pressure and send all fuel back to tank, consider a filter almost completely plugged, another thought is some pumps have a filter bag at pickup and have been known to collapse and restrict flow. perform some thought out tests !

1 out of 1 people think this is helpful.
6,960

Is your regulator on the fuel rail at the engine? You describe it like it was just one way valves or a regulator contained in the pump. To me that's unusual for Ford because they have used the bosch design regulator and a return line historically. it locates on the engine's fuel rail and relieves pressure based on throttle opening or closing. it has a manifold vacuum source hose attached to its nipple right? or did they change it to be like a jeep or some shipt. They have a idle pressure, and a WOT pressure, so if you unplug the vac. source, the pressure goes max. If they changed them to the jeep design, and you cant get one to work? (i'm not surprised) there is a fuel part that can be improvised for that after you identfy and test adequately.{ jeeps that have sprung valves can be adapted to another mfr's part} another thing that has happened historically is aftermarket crap doesn't flucking work. Excuse me, Ask your Ford Garage to help figger this with you and check for service bulletins. Carter always made Ford pumps but who knows. see what they say.

2 out of 2 people think this is helpful.
10

7jimmy7, and dannyi, my fuel filter is new one..just replaced it..second the fuel pressure regulator is located on the fuel assembly within the fuel tank, between the pump and the line connection pipe..my engine( ford.4.0 v6 job build 2) has what im told is just a dampening valve on the fuel rail..it has no vacume line going to it. my fuel system has only 1 line, the pressure line, NO return line..again after fuel assembly replacement everything work fine( correct fuel pressures, STFT, LTFT both near 0+- at idle) but within a few weeks fuel pressure drops, LTFT peeks at 25 and engine codes lean..which is why i considered the possibility of BAD parts being the cause.. now i am on my 3'd exchange replacement..could their be an over pressure issue going on that could cause regulator failure such as a sticking fuel pump relay?( i would think in that case the excess pressure would just bypass at the regulator.) ?? any thoughts??

1 out of 1 people think this is helpful.
10

sry the pickup screen/bag is new too!!

6,960

The system has been redesigned since i was very familiar. The new design IS like a jeep was in the mid 90's. The fuel is pushed up the line and a one way valve prevents return and loss of pressure. the valve is contained in the pump and sender assembly. since there is no regulator found on the injector fuel rail, there is no regulator. it is just a prevent valve. your test readings improve with a new part and then the problem recurs. then your test readings show valid cause of lean condition. The part repeatedly fails. Time to ask Ford. there may be a bulletin. an update, or a different part. happens all the time. i do not think your pressure is too high. and I think The Ford service techs should be allowed to verify your readings and find the cause as well as recommend any engineers bulletin or update. a fuel pump relay issue would have other symptoms like you can hear the pump running and it drains the battery. This would not increase the pressure, but simply maintain the available pressure. You need the latest Ford info and the latest part. If the aftermarket part has issues, you need to stop using it and inform them and get your money refunded. Then appeal to them to pay to prove their part keeps failing. This is not the first time, there have been aftermarket pumps failing in strange ways since federal mogul designed the one for the mayflower.

1 out of 1 people think this is helpful.
6,960

Your data about injector time? That is another subject after the pump pressure issue is resolved first. That decides, in the computer, to measure the needed fuel amount to accumulate for the engines needs based on all its sensor data. first you get the pressure and volume tests to pass, then you can pick that fly shipt out of that pepper.

1 out of 1 people think this is helpful.
6,960

fuel system pressure is measured with a mechanical high pressure gauge. It is attached to a service port in the injector fuel rail. when the key is in run, the pump powers up and pressurizes the rail and the gauge. when the key is off the system sits and holds rest pressure. There are specifications published to refer to. If the system had a regulator? disconnecting it with the engine running would show you the pumps ability to provide a higher pressure because the regulator cannot modulate. If yours has no regulator, that means the manufacturer is trying to run a higher pressure deliberately to reduce emissions and improve fuel economy and increase the effecyiveness of every drop of fuel. CAFE regulations have demanded ever increasing results from the manufacturer. This is their latest attempt to comply. Give them a chance to test it and let you have the newest engineer corrections implemented, or the inferior part be identified if it is at fault, please.

1 out of 1 people think this is helpful.
6,960

effectiveness, (not effecyiveness) but yea, those scan tool numbers are clues about the control of injector use, it cannot sample and report fuel pressure. Conversely, if fuel pressure readings and volume tests are found within current corrected spec ? (after bulletin or recall research ?) Then those numbers are meaningful and they're the result of the computer responding to sensor data. If the sensors are out of range they can affect the plan mapped out by the computer to run the engine. Those kinds of tests and verifications are supposed to be setting codes, that lead to pinpoint tests, that give readings, that are compared to Latest spec from engineering. Back to square one again. What is the first step in the pinpoint test for the lean condition ? what does the latest TSB say ? That is where you are currently in the diagnosis. In my humble opinion.

1 out of 1 people think this is helpful.
6,960

I read some threads about that KIND of "Truck" today and saw what your (single tube port, fuel pump and sender assy) is supposed to resemble, I see they have a damper for a return. That just means that when the pressure exceeds calibrated spring tension, the fuel stops getting forced up the line and out that single tube port. It never leaves the tank under pressure in that circumstance. If you have readings below spec, you have to pull that 9H307 pump and sender assembly out, and find out why that modulator or damper is sticking open, or obstructed. The other things in the pinpoint test would include the volts supplied is not dropping off due to loose fitting connections or poor ground. Every connector that has been placed between the pump and the other end of the harness must be tested, so you start at the component, the pump. you could be failing to give it the power to run, or having resistance building heat in a connection thereby, exponentially raising the resistance proportionate to the resulting heat. This is likely, if you probed the connectors from their faces rather than back probing. Then they fit like socks on a rooster. all the pumps you can get will do the same. The rest of the stuff I read was not about that specific system, and can be misleading if you dont notice the system components are different. The model years are newer, and the system again has a return tube port in the newer ones. Just like jeep, they went cheap and dirty, then designed a speed controlling jobbie and a pressure sensitive newer sensor dealie. Yours is the cheap and dirty, so keep it simple, if your damper or modulator is not stuck or obstructed? It has to be lack of current flow successfully getting through to run it? or a ground that has too many ohms to ground. This is all regarding a weak fuel pressure reading having been verified during the first test. I hope I was clear, your system is not full of those other parts because it was an interim system.

Best Answer
10

DannyI: your last post was right on the mark.. my truckdoes have the different system..and yes u described exactly how my fuel system was designed to work..which is why i was not getting wht the replacement parts keep failing..i did however ponder the power/ ground wire theory as well..i have swapped out the fuel pump relay with NO increase in pressure..I will get into the ground circuit ASAP ..I will hook up my fuel pressure tester at the fuel filter inlet hose and go from their..that should give me a more direct reading from the pump..possibly hotwire the fuel pump from an alternative power/ ground source and confirm readings against the harness wireing..i also considered the possibility of having some kind of foreign blockage within the fuel line or the fuel rail ( extremely unlikely)..thanx for all of your insight..u have been a great help, and i will keep u posted as to what i find out..

6,960

Last winter, i had a car that had intermittant operation of the fuel pump after replacing the entire fuel pump module. The stories on the internet were all blaming the design and the manufacturer. I found on that car by checking the supplied voltage (during the event) that temperture was the cause of the intermittant and it was measurably affecting the current flow. Having made sure every way we could that the wires were in good contact, I started going after the supply harness and went to a connector that further up the harness. Just back probing it with a thick paperclip while the vehicle was being operated by a helper, and I was below the fuel tank, just pressing the clip in alongside the wire, I heard the fuel pump start, They had been adding a battery to the system to run their old pump and had physically disturbed the wire connector. Just the pulling at it had widened the split tube on one side of the connection. so that fit like a stretched tube sock. That car maker uses all aluminum wiring and connectors to save weight. Then they spend millions on making everything not fit, or protecting the fragile connectors. nuts. But taking it apart and carefully restoring the shape finally had the car dependable. the fuel pressure was consistent after that.

The computer port on my 2003 ford sport tract is not working, can not get any reading from the port. Have checked the wiring and fuses

6,960

There could be a service bulletin about comm. error. They can blow a fuse if there was some issue.

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