02' Won't Start When Hot
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02' Won't Start When Hot
I have an 02' with a 5.4 that wont start when the engine is hot and the fuel tank is low. It will start fine once it cools off and will start fine hot when the tank is full. Anybody have any idea what could be happening?
Thanks, Tony
Thanks, Tony
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I hate to ressurect the dead.. But
My Boss's truck, '01 5.4, has the exact same problem.
Trying to figure out if its a sensor issue, a fuel pump issue, or possible injector leaking..
It will eventually start, but runs very rough until it clears out.
Check the fuel pressure, as suggested above, on a HOT engine is not in my window of comfort, and it only has the problem when the engine is hot.
My Boss's truck, '01 5.4, has the exact same problem.
Trying to figure out if its a sensor issue, a fuel pump issue, or possible injector leaking..
It will eventually start, but runs very rough until it clears out.
Check the fuel pressure, as suggested above, on a HOT engine is not in my window of comfort, and it only has the problem when the engine is hot.
Lead Driver
Joined: Sep 2006
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What you need to do is try to find out if the motor is flooded causing the hard start.
If yes, an injector/s may be dumping fuel and causing the issue, the regulator may be leaking fuel into it's vavuum hose causing flooding.
If no, the fuel supply may be to low for injection.
In that event, the pump may be faulty, the regulator may be faulty.
Until these checks are made you don't know what is happening.
Good luck.
If yes, an injector/s may be dumping fuel and causing the issue, the regulator may be leaking fuel into it's vavuum hose causing flooding.
If no, the fuel supply may be to low for injection.
In that event, the pump may be faulty, the regulator may be faulty.
Until these checks are made you don't know what is happening.
Good luck.
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whelp/ we just checked the FPR... no fuel in vac line.. pulled it of with engine running, seemed to load up, hence i would imagine the FPR is working...
one thing though.. PVC vals was making this annoying buzzing sound.. when shut the truck off, rattling slows and then "clunk" as the guts inside the valve dropped.. never head that before
one thing though.. PVC vals was making this annoying buzzing sound.. when shut the truck off, rattling slows and then "clunk" as the guts inside the valve dropped.. never head that before
Lead Driver
Joined: Sep 2006
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Well no, the vacuum line off won't load up the motor 'unless' the regulator is faulty.
If you don't plug the hose with your finger it would have an effect on idle from the extra air.
Normally the vacuum line lowers the fuel pressure at a time the motor does not need the full higher pressure but only about 5 lbs +/- change.
At higher throttle openings the vacuum is less allowing the fuel pressure to rise a small amount and not be influenced much by engine vacuum until the motor decellerates with high vaccuum (throttle closed) where the pressure will drop a little more due to the short time higher vacuum in the 22 inch range.
Good luck.
If you don't plug the hose with your finger it would have an effect on idle from the extra air.
Normally the vacuum line lowers the fuel pressure at a time the motor does not need the full higher pressure but only about 5 lbs +/- change.
At higher throttle openings the vacuum is less allowing the fuel pressure to rise a small amount and not be influenced much by engine vacuum until the motor decellerates with high vaccuum (throttle closed) where the pressure will drop a little more due to the short time higher vacuum in the 22 inch range.
Good luck.
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I did plug the vac line...
Guess i should also state that I've been programming fuel injection computers for about ten years now... just not on Ford Trucks... RX-7's.
the stuff i'm used to dealing with (adjustable aeromotive FPR's, Haltec and Microtec fuel computers) is a bit more advanced that whats on this truck...
I'm used to being able to look at a real time engine data page and see all the parameters laid out in front of me, including all the sensor voltages as well as injector duty, crank signal and wideband o2..
having that makes it MUCH easie to pinpoint a problem...
this "old school" trial and error stuff drives me nuts..
I am going to have to build an adapter for my aeromotive fuel pressure sender and get a good pressure reading on this truck.. unless there is another economical way that someone else has figured out..
one more thing... the boss has a full tank o fuel for the past couple days... and the problem hasn't resurfaced...... i'm bettin when he starts running on empty again it comes back......
Guess i should also state that I've been programming fuel injection computers for about ten years now... just not on Ford Trucks... RX-7's.
the stuff i'm used to dealing with (adjustable aeromotive FPR's, Haltec and Microtec fuel computers) is a bit more advanced that whats on this truck...
I'm used to being able to look at a real time engine data page and see all the parameters laid out in front of me, including all the sensor voltages as well as injector duty, crank signal and wideband o2..
having that makes it MUCH easie to pinpoint a problem...
this "old school" trial and error stuff drives me nuts..
I am going to have to build an adapter for my aeromotive fuel pressure sender and get a good pressure reading on this truck.. unless there is another economical way that someone else has figured out..
one more thing... the boss has a full tank o fuel for the past couple days... and the problem hasn't resurfaced...... i'm bettin when he starts running on empty again it comes back......
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Lead Driver
Joined: Sep 2006
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The pump's only cooling is the fuel is sets in.
Low fuel might be a problem.
Normally low fuel does not cause a problem because there is enough fuel left to cool it when the gage says empty before there must be fuel added to keep going.
If this pump begins to seize at low levels, it need to be changed.
It won't get any better.
Good luck.
Low fuel might be a problem.
Normally low fuel does not cause a problem because there is enough fuel left to cool it when the gage says empty before there must be fuel added to keep going.
If this pump begins to seize at low levels, it need to be changed.
It won't get any better.
Good luck.
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