Recently posted on a recently acquired Falcon (got the fuel leak sorted out). Now there's a new potential issue. A few weeks ago I hadn't driven it in a few days. When it started, the oil pressure light stayed on for probably a minute. I checked the sending unit. It was old, and leaking a bit, so I replaced it. However, a few days ago, again after not driving for over 24 hours, it did it again.
Once the light goes off, it stays off...at idle, under throttle, etc. Additionally, if you park and then start the car shortly after, it goes off quickly. Even after sitting hours, it might stay on a max of a couple of seconds. I thought it might be some sort of electrical issue, but today I went and bought an oil pressure tester from Harbor Freight. The Falcon hadn't been driven for over a day, so I tested it. Upon start-up the mechanical gauge registered zero oil pressure for close to a minute. It then promptly shot up to 42 PSI at idle (bouncing slightly, but the idle is also a bit uneven, pulling the choke evens the idle and reading out). Revving the engine brought the reading up to 51 PSI (not sure of the exact RPMs, but less than highway speed). With my foot on the accelerator, the reading doesn't bounce around.
Oil was changed by me several weeks ago. Filter is a Motorcraft unit. Oil weight is 10w-40 with a minor amount of Lucas zinc additive. Oil level is fine.
Any thoughts on what to check next?
Once the light goes off, it stays off...at idle, under throttle, etc. Additionally, if you park and then start the car shortly after, it goes off quickly. Even after sitting hours, it might stay on a max of a couple of seconds. I thought it might be some sort of electrical issue, but today I went and bought an oil pressure tester from Harbor Freight. The Falcon hadn't been driven for over a day, so I tested it. Upon start-up the mechanical gauge registered zero oil pressure for close to a minute. It then promptly shot up to 42 PSI at idle (bouncing slightly, but the idle is also a bit uneven, pulling the choke evens the idle and reading out). Revving the engine brought the reading up to 51 PSI (not sure of the exact RPMs, but less than highway speed). With my foot on the accelerator, the reading doesn't bounce around.
Oil was changed by me several weeks ago. Filter is a Motorcraft unit. Oil weight is 10w-40 with a minor amount of Lucas zinc additive. Oil level is fine.
Any thoughts on what to check next?