I have a 1992 Cararo with the 305/TBI. Motor has around 140,000 miles and the oil pressure has been great from the time I got the car. I started it yesterday and noticed that the oil pressure guage was reading really low. At idle it is a hair above the red zone and under hard throttle it makes it way up to about halfway. I started using the Pensoil brand motor oil recently with the cleaning agents in it. Could my pressure problem be due to the filter becoming clogged with junk from the motor??? Or should I troubleshoot the pressure sending unit or oil pump???

 

Change the sending unit first. They are a common failure.

 

First thing you want to do is put a mechanical oil gauge on it. That will tell you what the pressure actually is. If its still low, change the filter but in my experience that doesn't affect anything. You can try going up a grade in oil, for example from 5w30 to 10w30, but that's a temporary fix at best. If the mechanical gauge reads ok, then you can check the voltage signal at the gauge's connection to make sure the sender is working properly. If you get good voltage there, change the gauge. If the reading is off, change the sender.

 

You need to do some basic troubleshooting first. As mentioned above, use a mechanical gauge to confirm the oil pressure.

Here's what I found with an engine that suddenly lost pressure

https://www.thirdgen.org/forums/tech...sure-idle.html

 

I am having an oil pressure problem with my 84 Camaro. My pressure is showing to be good when I start it up. After I drive and the motor heats up, my oil light will come on while I am sitting at a light. It goes off when I start driving again. I changed oil and filter about 500 miles ago. I am going to change oil and filter again tomorrow. This car only has 56K miles. SUGGESTIONS?

 

I fixed the problem!! It was the oil pressure switch/sending unit. Oil was leaking through the unit and the signal it was giving was a screwed up. Simple $40.00 screw in part and it's fixed!!

 

That's good news. I only ever saw that once before and it was on a 2001 Mailbu. Gauge was reading good pressure, he noticed the oil leaking on the floor.

 

would oil sending unit cause fuel pump failure?

 

Electric fuel pump are just electric motors. A power and a ground circuit. If the pump fails, the motor or circuits to it have failed. Lack of oil pressure in the engine would have nothing to do with it.

 

Good lord are those up to $40 now? 4 years ago I could get them for $15. Then last year I got one for $29 or so. Ugh... And yeah, they're very prone to failure. I dont really pay much attention to my oil pressure gauge anymore. All 3 gave different readings when going bad, and all 3 had consistent readings when they were good, and none of them showed the same oil pressures. There's at least a 10psi variance from sending unit to sending unit.

 

None of the factory gauges are considered accurate enough. Using aftermarket gauges and sending units is always a nicer way to go but also costly for many people.

 

It won't cause failure of the pump, but on a TBI system it can cause the pump to not get power IF the regular Fuel Pump Relay or circuit is bad AND the oil sending unit is registering less than 4PSI oil pressure (whether or not the actual oil pressure is above that or not)