I have a 2001 F150 5.4L. The truck has 180,000 original miles but 35,000 miles on the refreshed motor. Its my daily driver to and from work everyday. Over the last week the oil pressure gauge would move up and down on initial start up and the oil light would come on. If I gave the truck just a little gas in park or accelerated in drive the oil pressure light would go off and the gauge would read correctly. Once the truck ran 2-5 minutes or so the gauge worked fine and the light stayed off. That problem only existed on initial start up. The last few days the gauge has worked correctly but the truck dragged on cold initial start up like the battery was weak. I drove the truck about 20 miles yesterday and everything was good. This morning it would turnover but wouldn't start. The gauges were acting weird and flipping back and forth. I changed battery this evening and it cranked and ran fine for about 10 mintues. I thought great fixed. I shut it off and tried to crank again; this time it just turned over and over but no start. All the gauges read correctly and radio plays fine but the Battery Light is staying illuminated with the ignition in the on position. I disconnected the battery and reset the computer but it did the same thing. Battery Light on, turns over great but no start. Its crazy becasue it started and ran fine 5 minutes ago. Can the alternator have a dead short and cause the vehicle to turnover but not start or the alternator have caused the draggy cold start and oil pressure gauge to act weird? Its got me baffled.....any help you guys can give is appreciated. I found this forum a few weeks back and wished I had it all along. Thanks

 

Do your gauges "sweep" when you try to start it? How about the anti theft light whats it doing? I think its possible to have the problem you are as a result of a bad connection at the alternator or it could be the anti theft system or the compputer could be bad. I'd start with the alternator connections.

 

The gauges do sweep after I reconnect the battery and try cranking. As far as sweeping after I have tried cranking it the inital time no. They do their normal things as if you were cranking the truck normally. They all go to zero or move to their ignition on positions. I've never had a problem with the anti-theft and the light doesn't appear to be on. Thanks for the ideas; maybe someone else has had these issues.

 

Was the battery light on when it was running with the new battery ? If so, check your inline fuse 2.5' from the alternator in the alternator harness.

Here's a normal 2001 5.4L start -

http://picasaweb.google.com/jbrew393...84705673453298

Other than that, check your connections @ the starter. Can be problematic as they corrode.

____________

Your description of your oil pressure gage would bother me a bit, but these vehicles do funny things when they have battery and charging issues.

____________

Do you hear your fuel pump charge the lines with the key turned to the run position? If not, the pump isn't working.

 

I didnt notice if the battery light was on while it was running. It sounded like the fuel pump was engage when I turned the key to the on position. I guess my main question; if everything is good fuel pump, battery, starter, wires and etc, will a dead alternator keep it from firing off and running. It cranks or turns over great just won't fire 8 out of 10 times. If it hadn't fired off I would be concerned about many other things but its firing off every few times which leads me to believe the alternator is shorted? I had some funny issues the days leading up to this which make me believe its an alternator.

 

If your over pressurize the fuel rail, she's not going to start. You might want to check the fuel system. Your CEL hasn't been on in the recent past has it?

= CheckEngineLight.

Try cleaning your MAF sensor as well.

Reboot after, - Wait a full 20 minutes before reconnecting the battery.

Your regulator on the rail could be going out as well or the crank sensor itself. Could be loosing connection. If the engine is real dirty underneath, that can cause intermittent issues, which would explain your sending unit (oil pressure) acting up.

That also could lead to battery problems from the starter connections. All the above is down below. Where the oil filter is located on that model, it's very easy to contaminate the sending unit wire.

 

If your starter turns like a normal car or truck, then your battery is fine. But if it's slowly chugging, then that could be an issue. Your alternator isn't used in terms of starting. It's simply a maintainer, keeps your truck running after it has started running. The only thing with this is that if your alternator is messed up or has a problem, then it won't charge your battery, and won't start your truck if there's not enough power. If you can get your truck running again, you can take it to an Autozone and htey have equipment to check the capacity of your alternator and battery. A suggestion would be to check all your wires and fittings for corrosion.