[pocket-rocket]

I'm not familiar with the 2.8, so someone else is going to have to chime in on this one. I know on my DOHC it is above the oil filter FWIW.

[cutlass supreme FE3]

Originally Posted by pocket-rocket

I'm not familiar with the 2.8, so someone else is going to have to chime in on this one. I know on my DOHC it is above the oil filter FWIW.

I will take some pictures tomorrow and hopefully any member can confirm if this is the switch or not.

cheers

[cutlass supreme FE3]

okay guys,
I checked it and found the oil pressure switch to be right besides the oil filter,
The thing that I found odd was the switch only has one wire. so how does the switch with one terminal supply power to the fuel pump??

[bszopi]

You may be looking at the knock sensor, not the oil pressure sensor. The OPSU should have at least 2 wires and it "controls" the fuel pump via a relay.

[cutlass supreme FE3]

Originally Posted by bszopi

You may be looking at the knock sensor, not the oil pressure sensor. The OPSU should have at least 2 wires and it "controls" the fuel pump via a relay.

could there be like two OPSUs??
auto parts asked if i had a gauge or only light in the dash and gave me the one terminal OPSU since I have a gauge in my digital cluster.
there is supposed to be a two pin and three pin versions of the OPSU as well.

here is the OPSU right side of the green oil filter. You can see there is only one tan wire which I think goes to the instrument cluster gauge.

[bszopi]

Hmm... Well, that is definitely the OPSU. And its definitely the gauge one (longer). Why it only has a single wire coming out of it baffles me. Unless, for some odd reason, you car doesn't have the interface with the fuel pump.

[cutlass supreme FE3]

Originally Posted by bszopi

Hmm... Well, that is definitely the OPSU. And its definitely the gauge one (longer). Why it only has a single wire coming out of it baffles me. Unless, for some odd reason, you car doesn't have the interface with the fuel pump.

Well the vehicle is a 1988 Oldsmobile Cutlass Supreme International with the 2.8L MFI motor. I had this car since new and that is the original OPSU and I never had it replaced. The dash is the blue lit digital type where there is a gauge not a oil light.

So if it does not have the interface with the fuel pump then the relay power output goes directly to the pump?
I get the 54 code but what would cause my idle to go up and down? I have replaced the fuel pump relay with a new one and problem persists.

[cutlass supreme FE3]

okay i went outside today and the temperature is -6 degrees celcius.

I have to crank the starter three times while pressing on the accelerator to get it to start. It will not start without the accelerator depressed.

once started the oil pressure gauge shoot up which is normal at cold starts.




the idles is at 1000 rpms


idles at 900 rpms


now at 1100 rpms




900 rpms

gas is full and alternator charging full


original mileage in kilometers and also you can see the idle dropped two bars



idle back up 2 bars 200 rpms


idles at 800 rpms now





anyone have a clue what could be wrong?

Now the focus is the fuel pump and i need to get a fuel pressure test done tomorrow.

[cutlass supreme FE3]

I was just outside and I did a quick test for the fuel pressure.

There is a shraeder valve on the fuel rail and i just depressed the valve down to see if any fuel comes out.
There is no gas at all. Okay, then I turn on the ignition for 5 seconds and off a few time so the fuel pump is supposed pressure the fuel rail. Wrong, the fuel pump does not operate at all. Okay, I crank it two times but it does not start and I got and depress the fuel rail valve and now there is fuel coming out.
I go and crank a third time and yes now it starts.
Now I got to figure where the fuel pressure is leaking from? most likely one or some of the injectors is leaking.

I'm slowly trying to pinpoint the problem area.

[bszopi]

Take the vacuum line off of the fuel pressure regulator and see if gas comes out of it. If yes, then you have a bad regulator.