1995 Oldsmobile 88 running rough and stalling
 

I have a 95 Oldsmobile 88 with 95k miles on it. We acquired this in 2017 with 40k miles on it. No issues until late last year. Car started guzzling fuel and would have random stuttering and misfiring. Changes plugs, wires, coil, fuel filter and a new idle air control (the old one failed when I removed throttle body to clean). Kept having issues repaired some vacuum leaks going to fuel pressure regulator and evap system, pcv valve, injector seals new o2 sensor and cat removal. During all of this the check engine would sporadically come on, never flashed, but I haven't been able to get a scanner that can read it yet. So now after everything car idles much better, took some time adjusting iac, drives okay but feels like it's losing some power and when making some turns it will stall or almost stall then fires back up. I have noticed though if the tank is lower on fuel the stalling seems to be worse. This thing has been driving me bonkers bc it will get so close to running right then goes haywire.


Growing up we have had countless GM vehicles with the 3.8, still currently have this and an 08 Pontiac grand prix that I will be posting about in the future. So I've had some experience working on these and this one has just thrown me off especially since I can't read the codes.


Any ideas? I've been looking into directly accessing the pcm using serial communication, i have 2 98 Dell laptops with hardwired serial ports that should work but I'm uncertain on what I'll need hardware wise to build a cable. I didn't know if the older computers would be better to use or just use a USB to serial adapter.

Thanks if you made it these far through my ramblings

tech 2 clone. if youre willing to put that money down. You NEED to have a diagnostic tool here. dont let the meaning of need get lost

you are wasting your time if you refuse to get an interface with your PCM.

Yeah. The OBD 1.5 requires special software. Need to see what the system is doing. The tool will save you time and money.

What is the fuel pressure?

Little late on my reply.... I've replaced the fuel pressure regulator and new vacuum lines around the throttle body.

For fuel pressure, at idle I'm getting 35psi, with throttle it will dip down to 30,31 psi. Minimum it should be 40.

Fuel filter has been changed. So weak fuel pump/clogged filter in tank? Or leaky injector?

Looks like a bad fuel pump to me.

What is the fuel pressure with the vacuum line disconnected from the fuel pressure regulator?

It jumps up to around 40 psi. I'm going to pull the tank and swap fuel pump.