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Old 03-11-2013, 08:16 PM   #11
iminhell
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Quote:
Originally Posted by 6SPD_soul View Post
Explain it, there have been a lot of people this winter with this problem. Cold start, cranks but no start. Spark and fuel and timing are present. Why are you convinced the fuel pressure sensor is throwing things off?

I agree it's a air/fuel problem. My car died for a few cold (05-10) days and exhibited soaked pig rich spark plugs, another SVT wouldn't start witout a fuel soaked rag over the intake tube to enrich the mixture.

How does the FRPS influence the AFR and why would it send strange readings in cold weather and then work fine in warmer weather?

I agree about the air/fuel ratio being the main problem, but if you have any ideas about why the FRPS signal would change depending on ambient temp that would be really helpful.


The key here is the time it sits not running, not how warm it is. I made the same mistake and it took me awhile to figure it out.
It's a typical FPR failure. The diaphragm leaks fuel into the intake manifold, that fuel puddles at the bottom, the high velocity of startup air sucks that fuel into the cylinder, the plug gets soaked/mixture is too rich to ignite, O2 is off at this point and the injectors are still spraying fuel. So you end up with way too much fuel, each time you add more to the problem.
As the car sits the fuel evaporates, you turn the key, the correct amount of fuel is injected and it starts like nothing's wrong.
Same goes for restarting after it's been running for some time, the puddled fuel has all been sucked through and burned up.

Odds are if he pulls the vacuum line on the FRPS it will leak fuel, dead giveaway.


Now granted this may not be the problem for others, but IMHO / by everything he's described, it is his problem/fix.


... and no, it will not throw a check engine light.
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Old 03-11-2013, 10:06 PM   #12
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I will give it a check this week. Like others have said, there are many posts on here about this problem and there is never a solution posted. If I find a solution, I will post it.
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Old 03-13-2013, 11:16 AM   #13
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Well, I towed it to the dealer (my father works at one). They replaced the coil pigtail and inspected the frps for leaks. No leak. They had it started and running a few times yesterday. It is cold out today and now it won't start and they claim no spark. They said that their Ford hotline has not diagrams for this model for troubleshooting!!! WTF I'm going up there today to see what's up!!!
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Old 03-27-2013, 11:32 AM   #14
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Just an update for archival purpose:

It's been at the dealer for a few weeks. Like I said, they replaced coil pigtail and it did not fix it. I switched the PCM relay with the headlight. it started everyday for a week for them. Then it would not start again. They diagnosed the coil pack today while it would not start. We will see if this is the real problem. I feel that the crank sensor has a weak signal. I'm picking it up tommorow and resume DD with it.

I did check the resistivity of the coil pack when it was not starting (a month ago) and it all checked out to be in specification.
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