My wife's '03 EB with 5.4l has recently developed an intermittent hard starting problem. It happens mainly when warm, but sometimes cold, and sometimes not at all. Usually it fires on the second round over, probably less than a second. When the problem occurs, it will crank over for 3 - 5 seconds before firing. There is no SES light, and it is not throwing any codes. When it finally fires, it seems to do so normally - no roughness, misses or high or low RPM's. I have tried releasing the key when it acts like it is going to do it, and then hit it again. Sometimes it will start normally on the second try, sometimes it will still take a few seconds of cranking.

Any ideas would be much appreciated.

 

Have you checked your fuel pressure? How about your air filter? If you put the key in the "run" position but don't crank the engine for about 7-10 seconds, does it start easily then?

 

Also, when was the last time you changed your fuel filter?

 

I have not checked the fuel rail pressure yet, also have not tried letting the fuel pressure build. Good suggestions. The fuel filter in there now has 23k miles on it. I try to change them at 30k, try being the operative word.

 

If it's not fuel-pressure related, it could also be a vacuum leak. Let us know what you find out!

 

Does the "Check Engine" light turn off while the engine is being cranked?

 

What would that indicate, pdqford?

I'm here to learn

 

Not all ECM's are set up the same, but Ford will typically turn off the check engine light and fire up the fuel pump if the ECM detects the crankshaft position sensor signal while the engine is in crank mode.

So if the light goes off while cranking that kinda eliminates the crank sensor signal as the culprit. If it then doesn't see the cam sensor, it doesn't know which fuel injector to fire (i.e., if the crankshaft position sensor reports that cylinder number one is at top dead center. without the cam position sensor the ECM doesn't know if it is at TDC on the compression stroke or the exhaust stroke). Some ECM's will fire fuel injectors randomly in an attempt to get it started but it might have to crank over a number of times before it fires the correct injector in relation to the crank/piston position.

 

It's going into the dealer this morning. I just don't have time to diagnose and fix it this time around. I'll let you know what they come up with.