Hello ya'll! I hope you can help me. I've got a 1999 Ford F-150 4.2L Flareside with 256,000 miles. I was driving yesterday and the oil light came on, the gauge didn't move. I pulled over as fast as I could and it was low on oil, I put a quart in, the light went off. I drove it to work (about 25 minutes) and the light came on again as I pulled in. Again no drop on the gauge. I changed the oil and filter (Motorcraft). I drove her home and the oil light came on again just as I pulled in the driveway (about 25 minutes). I've never had this issue before. Please help! She's been a great truck (even with all those F150 quirks)!

 

The oil pressure gauge is just a dummy gauge. I believe it drops at 8 PSI. Anything beyond that and it stays pointed in the middle of the gauge.

You need to mix in an actual gauge and get actual pressure readings to at least eliminate a mechanical issue. A bad sender is a lot cheaper to deal with, sure, but no time to get complacent and possibly lose an engine.

 

Where would I install a gauge?

 

When you say a bad sender, do you mean the oil pressure sensor?

 

The oil pressure sensor is an ON/OFF switch that closes through to the dash to power the light and signal the dash electronics to move the gauge to it's normal position.
Remove the connector from the pressure sensor.
Does anything change?
Ground the connector does anything change?
This is checking the integrity of the lead and circuit for operation.
Next do the pressure test with a gauge to see what condition you have for oil pressure.
These are two separate items you need to know about to be sure of your issue.
Good luck.

 

I have already replaced the oil pressure sensor. I will check those items you mentioned. How do I do a pressure test? Where do I put a gauge to test the oil pressure? Thank you for your help!

 

You have to remove the sensor and screw the gauge line into the hole. You can use a "T" fitting to reinstall the sensor.