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Discussion Starter #1
One month before when i took my car for a long journey (1200 km) one time i noticed the car didn't accelerate and lost its power, i stopped at a gas station and checked nothign found abnormal, when i started the car it got ok and i didn't get this issue again.

after that i sued this car daily 200 km drive, i didn't get this issue.

Again i went on a long journey, Yesterday i was returning back home the issue started. its like when go on slop up or down the car suddenly loses its power, RPM comes down though give fuel, like rpm doesn't shoot up. if on flat road it goes smooth. if i turn ignition off and start the engine on slope up/down it get its power and accelerate normal to full speed when any slope comes again it loses its power. i had to turn off ignition and start engine again every time when it did so.

I had a check car stopped it idles good, but no power if off and start again it becomes good and rpm goes normal. checked fuel rail pressure when the issue was there, pressure was low. i doubted the fuel relay and i swapped with another one, still the issue was same.

my questions
1- what are the steps i have to follow for further checks ( no engine code at present)
2- why it gets ok every time i start it
3- I noticed at beginning it ran good and the issue started when engine got hot, can it be related to any component? (due to less power heat didn't raise or come to middle)
4- the car uses return fuel system as i know, the filter have a return line, any advice to change it?
5- what about fuel pump? can this get ok only at start and goes weak every time?
 

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You may have more than one problem. Have the engine computer scanned for trouble codes & post All code Numbers, as they can offer up good trouble shooting clues.

Good trouble shooting idea to try swapping out the fuel pump power relay, as its a common problem part.

When the fuel pressure was low, did you measure under load operating voltage to the fuel pump??? If fuel pump operating voltage is ok, but fuel pressure is still low, when the problem is present & the engine is running, try removing & reinstalling the gas cap to equalize fuel tank pressure & see if the engine power immediately returns. If so, suspect the gas cap isn't properly venting the fuel tank, so replace the gas cap with a Ford part.

Is the fuel filter due, or past due for scheduled replacement??? If so, do that & see if the fuel pressure returns to normal.

When you've had the problems, were you using a quality fuel, one that your certain that its vapor pressure is properly adjusted for the hot climate your in. I'm thinking of possible vapor lock problems, with the fuel boiling in the lines under hot weather & high speed highway operation.

Some thoughts for consideration, let us know how your trouble shoot goes.
 

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Discussion Starter #4
thnaks for the replies,
As i mentioned no engine codes read on my scanning tool. Fuel pressure regulator can be a suspect as jag1959 told, i will look into that. Is it located over the tank under the vehicle?
I didnt try to open fuel tank cap and have a check, may be worth to see that too.

i will work on it and let you know the updates.
 

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If your fuel pressure regulator is on the engine as shown above, you might try removing its vacuum line to see if its wet inside with fuel, if so, replace the fuel pressure regulator.
 

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Okay, just to be clear do you have the correct 2001 PCM in your car now? Theses issues are with the 2001 PCM?

Also I have to ask the obvious, is the gas tank empty when you have these problems? Fuel gauge reading correctly?

When you checked the fuel pressure and found it low was the engine running or not?

I would change the fuel filter if it's been 50,000 km or more since the last time it was changed.

Make sure you hear the fuel pump run every time you cycle the key to on.
 

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Discussion Starter #8 (Edited)
Okay, just to be clear do you have the correct 2001 PCM in your car now? Theses issues are with the 2001 PCM?

Also I have to ask the obvious, is the gas tank empty when you have these problems? Fuel gauge reading correctly?

When you checked the fuel pressure and found it low was the engine running or not?

I would change the fuel filter if it's been 50,000 km or more since the last time it was changed.

Make sure you hear the fuel pump run every time you cycle the key to on.
1- yes i have the correct PCM now
2- gas tank has no issue , gauge is reading correct
3- i checked when engine running, i opened the cap of the valve on fuel rail, pressed the vale, very less pressure and engine about to die, then get idle when relased
4-fuel filter replacement is due, but i drove this car last night to another city 30km far, i didnt have this issue till i stop at the 3rd trafic signal in that city. i returned back after 3hrs and it worked smooth till i reached. i doubt anything related to heat / engine copartment temperature? what it could be? if fuel filter is the issue, it must have given me truble whole the way.
5- i hear the fuel pump noise every time i turn the key

in my car i see the fuel rail doesnt have a return line. as i remember the filter itself is having a return line. so where can be the regulator located? or am i missing something?

If i want to check supply voltage and relay drive voltage from PCM, how to access the terminals? i am thinking to pull the relay and insert think insulated wire to bring it out and put the relay in place so that i can check it when the issue come, is it the correct practice?

Edit: i opened the gas cap last night to see if any different , in both cases the issue remains the same.
Thanks
 

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Check the regulator next.

I think the fuel system on a 2001 Vulcan might be mechanical return (sort of an oddball year).

Check for fuel pump voltage at the IFS switch in the trunk. Don't rig the relay up like that.
 

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1- yes i have the correct PCM now
2- gas tank has no issue , gauge is reading correct
3- i checked when engine running, i opened the cap of the valve on fuel rail, pressed the vale, very less pressure and engine about to die, then get idle when relased
4-fuel filter replacement is due, but i drove this car last night to another city 30km far, i didnt have this issue till i stop at the 3rd trafic signal in that city. i returned back after 3hrs and it worked smooth till i reached. i doubt anything related to heat / engine copartment temperature? what it could be? if fuel filter is the issue, it must have given me truble whole the way.
5- i hear the fuel pump noise every time i turn the key

in my car i see the fuel rail doesnt have a return line. as i remember the filter itself is having a return line. so where can be the regulator located? or am i missing something?


If i want to check supply voltage and relay drive voltage from PCM, how to access the terminals? i am thinking to pull the relay and insert think insulated wire to bring it out and put the relay in place so that i can check it when the issue come, is it the correct practice?

Edit: i opened the gas cap last night to see if any different , in both cases the issue remains the same.
Thanks
OK, good trouble shooting feedback, too bad the gas cap test didn't prove positive, as its an easy fix!!!!. Your answer in #3 above, about the engine idle recovering when you pressed the fuel rail Schrader valve to check fuel pressure, is a good clue.

A few things come to mind that could be causing this.

1) As it seems to happen after a long drive, or in traffic, I suggest again, fuel line vapor lock, from the fuel boiling after a drive in the hot weather your having now in Saudi Arabia. If the problem began right after you filled up with fuel from an off brand, or out of the way fuel station, that was selling sub-standard fuel that didn't have its vapor pressure properly formulated for the temperatures your having this time of year. If you have Chevron/Texaco/Caltex, Shell, or BP gasoline available, maybe try one of them & see if things improve.

2) An aged, weak, failing fuel pump, or pressure regulator assembly, that's likely located in the fuel tank, is having intermittent problems building & holding fuel pressure. Could be a grain of sand that's gotten past the in tank fuel pump "sock" pre-flter and lodged in the pressure regulator, or drain-back valve holding it open so that the pump can't build proper fuel pressure. So perform a proper fuel pressure test, with a gauge connected to the fuel rail Schrader valve test port (where you bled the fuel pressure off in your trouble shoot) & post your fuel pressure Numbers with the engine cold and at idle & at say 2500 rpm, then do it again when the engine is warm & about to stall. EDIT: Also leave the fuel pressure gauge attached to the fuel rail after you turn the engine off, then time & post how long it'll hold fuel pressure & what the fuel pressure number is.

3) A line, or gasket, or seal problem, in the fuel tank, with the fuel pump/pressure regulator assembly, intermittently picking up air & injecting it into the fuel line, or with shifting debris clogging the in tank fuel pump pick up sock pre-filter, so the pump has problems sucking up enough fuel to build pressure.

4) As has been suggested, maybe intermittent low operating voltage to the fuel pump. As has been said, the in trunk fuel pump inertia cutoff switch electrical connector is an easy access test point, to back probe the fuel pump electrical B+ feed, as it'll test most of the electrical wiring to the fuel pump for under load voltage drop.

More thoughts for consideration, keep us posted on your trouble shoot.
 

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Discussion Starter #11
pawpaw Thanks for the suggestion, i will work on it and give the feed back. i dont have a gauge to connect, any how let me think of a way to get it done. few months before i replaced a fuel pump due to wrong diagnosis (car didnt start - it was relay issue), the replacement didnt exactly fit into the sealing, but did some modification, but i dont think it may cause this issue. any how let me do electrical test first and the pressure checks.
 

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Yeah, it looks like your temps there get up to like 45ºC (113ºF), so vapor lock is definitely a possibility there if your pump is not sealing and generating enough pressure. I think we all agree here you need to get a fuel pressure gauge on the car and monitor the fuel pressure.
 

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Discussion Starter #14
I checked with few workshops and no one had a gauge to check the fuel pressure, any how i changed the fuel filter and the performance of the engine is good now. i had a drive yesterday 100km to my work place, at mornign ambient was low and no issue, while i was returning back say after 80km drive, i had to give patrol suddenly to overtake another vehicle and the power suddenly dropped. it gets ok as before after retart, but this time its better than previous cases.

Any how i am thinking to explore again to find a workshop to check the pressure, mean time i am thinking to connect my scan tool and check live data while driving.

I hope a lean fuel condition will indicate STFT to be +ve and it can be an indication that fuel pressure is low thus supply is less... ???
 

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OK, more good trouble shooting feedback & to hear you have some positive results by replacing the due for replacement fuel filter.

The engine running ok at cooler ambient morning temperatures, but acting out on the return trip with hotter ambient temps is a good clue. I agree it would be a good idea to connect your scantool to be able to monitor fuel trim & other live sensor feeds while driving, like fuel trim & the fuel tank pressure sensor PID to the computer.

Also a good idea to pursue measuring fuel pressure when the problem is present. I would think a vehicle Dealer service department could measure fuel pressure, or you could order a fuel pressure gauge on line from, Harbor Freight, for as little as $20 US, + shipping, or maybe if funds aren't tight, opt for the more expensive one that has the fuel pressure bleed valve fitting, so that you can easily perform a fuel volume delivery over time test, to check the fuel pump ability to deliver enough fuel volume in high demand times, like when passing another vehicle!!!!! Keep us posted on your trouble shoot.
 

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I find it hard to believe you couldn't find a shop with a fuel pressure gauge. It is one of the most basic mechanic tools, so a shop that doesn't have one isn't running a very good operation (you wouldn't want to bring your car there). They aren't that expensive, and any decent auto parts store should have one.

Having fuel trim and fuel rail pressure data while the engine is experiencing the issue would be helpful.
 

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Discussion Starter #17
I checked the live data when the issue came, the STFT always remained +ve. nearly 10.
i am waiting for week end to check the pressure or buy a gauge.

mean time i drive this car every other day to work, 100km. today i thought to drive it at high speed, to see if any sign of lack of fuel appers. i could easily keep the car moving at 160km/h (100 mph) for 20km. i couldnt notice any problem. The ambient was low but stil hot.


my question is...
1) can we stil doubt any isssue with fuel pump? i know when i get back to the city i live the issue will appear since it will get hot after noon.
2) what must be the normal fuel pressure?
 

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When you're going 160 km/h the engine is getting plenty of cooling and the fuel is flowing through the lines at a very good rate (not enough time to heat up before going into the engine). When you stop or drive slowly the fuel in the rail has more time to heat up and vaporize if the rail is not under enough pressure (vapor lock). So no, we can't rule out the fuel pump yet.

Normal fuel pressure spec is 35-55 PSI or 240-380 kPa. Check with the engine running when it's doing it.
 

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^+1 Will be interesting to find out what your fuel pressure reading is when the problem is present.

STFT of 10, says the computer is having to add fuel to correct for a lean condition its detected, so it might also be helpful if you would post the scantool MAF sensor PID & upstream before cat converter O2 sensor max & min voltage switching range & frequency readings for both cylinder banks.
 

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Discussion Starter #20
Finally i decided to buy a gauge not to look for a one from a workshop, it seems most of the mechanics are not aware of checking fuel pressure..

Yesterday i got the issue after a long drive and i fixed the gauge to know the readings.

engine stopped, fuel pump in service by bypassing the relay - 55 psi
Fuel pump stopped - pressure drops with slow rate
at idle - 55 psi
when given gas - 15 psi and engine rpm doesnt go up.

i think i have to check the same when in normal condition too, will update.

just few questions...

1) if the pump is capable to give 55 psi and maintain good flow at high speed, how can vapor lock occur??

2) at this point can i conclude that the issue is with the pump?

3) any more checks required? i am thinking to keep the gauge connected and have a drive today to see how it behaves, i found a way to bring it to the windscreen and read while driving, may be a good idea?
 
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