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SportTrac Discussion
Engine & Drivetrain
Sport Trac a little trouble starting?
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<blockquote data-quote="scott degroot" data-source="post: 855840" data-attributes="member: 66039"><p>Richard</p><p></p><p></p><p></p><p>Not sure what you are getting at. My only point is this. Without a fuel rail pressure sensor the pcm has absolutely no way to determine if there is fuel pressure present or not so it would be impossible for the pcm to not fire the ignition due to lack of fuel pressure and also even on vehicles that the pcm is able to monitor fuel pressure output the pcm still will never not fire the ignition due to lack of fuel pressure. If you are experiencing a prolonged crank due to fule pressure bleeding off you will find if you crank long enough it will fire. The reason it starts sooner if you cycle the key is that basically you have activated the pump 2 times without firing the injectors, this builds pressure alot faster in the system then trying to actually start the engine. By just trying to start it you have to take into account that the injectors are now firing without adequate fuel pressure and volume, also you have to consider the voltage drop at the fuel pump due to the starter being engaged, most will drop to somewhere around 10-11 volts at the pump while the engine is cranking. While this may not seem like alot it is enough to decrease fuel pump speed which will also decrese the pumps ability to supply the proper amount of fuel.</p></blockquote><p></p>
[QUOTE="scott degroot, post: 855840, member: 66039"] Richard Not sure what you are getting at. My only point is this. Without a fuel rail pressure sensor the pcm has absolutely no way to determine if there is fuel pressure present or not so it would be impossible for the pcm to not fire the ignition due to lack of fuel pressure and also even on vehicles that the pcm is able to monitor fuel pressure output the pcm still will never not fire the ignition due to lack of fuel pressure. If you are experiencing a prolonged crank due to fule pressure bleeding off you will find if you crank long enough it will fire. The reason it starts sooner if you cycle the key is that basically you have activated the pump 2 times without firing the injectors, this builds pressure alot faster in the system then trying to actually start the engine. By just trying to start it you have to take into account that the injectors are now firing without adequate fuel pressure and volume, also you have to consider the voltage drop at the fuel pump due to the starter being engaged, most will drop to somewhere around 10-11 volts at the pump while the engine is cranking. While this may not seem like alot it is enough to decrease fuel pump speed which will also decrese the pumps ability to supply the proper amount of fuel. [/QUOTE]
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SportTrac Discussion
Engine & Drivetrain
Sport Trac a little trouble starting?
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