Oil Pressure Sensor Issues
 

Hi all,


1989 Ford F-150 RWD 302 5.0 5 Speed Trans

I am somewhat stumped and really can't figure out the issue with my Oil Pressure Sensor.

I was driving last week, and all of a sudden my Engine light came on, oil pressure was completely lost, and I noticed the smell of burning oil. I quickly came right back home and realized I just pissed out a lot of my oil. I located the leak and found the oil pressure sensor to be the culprit. I ended up doing and oil change with new filter, and replaced the oil pressure sensor. I then go and start my truck again and there is no oil pressure to the gauge, and my engine light is still on. Now I have searched and found that the oil gauge is a dummy gauge and really just tells you if you have oil or not.

I tested with a test light to make sure the oil pressure sensor wire has power, and it does. I then tested to see if oil was getting to the sensor, by cranking with out the sensor on. It pissed right out. I also tested the codes by running an eec-iv tester, and didn't get anything related remotely to oil pressure. I even tried replacing the oil pressure sensor to another new one with no results. I still have no oil pressure on the gauge and the engine light is still on. Is there anything else I can do or test for?

Thanks in advance for the support!

Yes, you really need to test your actual oil pressure with a mechanical gauge.The OEM dummy gauge will deflect your dash gauge with around 7psi. Apparently you may not have that much now and could have damaged your bearings with the lack of oil. The OEM sender is nothing but a switch calibrated to around 7psi.
You should have shut down the engine right away and not driven back home because the engine was likely severely damaged by then.

Thanks for the advice. From what I remember, when I was testing where the leak was (with the engine full of oil again), the old oil pressure sensor was sending a signal to the gauge and it read that I had pressure. I will put the old leaking one back and test today, to see if it might work. I replaced the original oil pressure sensor with a Duralast one from Autozone I think. Do you think that I need to get one directly from Ford? I will also test with a mechanical pressure gauge as well.

Thanks!

You'd probably hear the lifters clattering if you truly had no oil pressure. Put a little dent on the end of the oil filter and look for it to pop out when the truck is started. Might pre oil the filter to be safe, in fact if the filter has oil in it the truck must have some oil pressure. Try a different pressure sender unit.

That's your problem. Stay OUT of the zone. You don't have to buy Ford/MC every time, but don't buy that garbage EVER.

Did you put back a switch the same size & shape as the original? Or did you put in a sender (much larger body than original)? Click this & read the caption:

https://www.supermotors.net/getfile/...chsenderv8.jpg
(phone app link)

The links in the caption explain what else needs to be done to convert from the idiot switch to the older sender.

The dent in the oil filter technique, that's hilarious. Gauges are available, very inexpensive.

I used the same size sensor and everything. I know autozone sucks, it is the closest shop to my house. I will be getting a manual gauge soon and trying that out.

I am also getting another switch from Napa tomorrow, hopefully better quality.

Thanks for the guidance everyone. I will let you know what reading I get from the manual gauge.

I don't know if an 89 is much different from an 87. I converted my 87 to an actual pressure gauge. I replaced the original switch with an actual sender and made no other changes or modifications to the dash or circuitry as others might dispute. It has been working great and quick responding for 20 years now.

A proper test gauge is a good idea to see what the actual pressure is. Grounding the wire should make the dash gauge move.

Putting a small dimple in the filter is a quick way to verify some oil pressure. It's not a long term solution, just a way to get a vehicle back into use when the oil gauge is malfunctioning. Let's the truck be driven while sorting the electrical problem.