SL1 won't start; low fuel pressure

I have a 1991 SL1 and it has had intermittent starting and running problems for a couple of years. To keep it running I had to keep pumping the gas pedal, otherwise it would die.

Now the car will not start at all.

The fuel pressure is 30 psi. I did not notice any damage to fuel lines like crimps.

The compression on each cylinder is around 160 psi.

There is spark to the new plugs.

I replaced the throttle position sensor.

Fuses look good.

A year ago, the fuel pump was replaced with an advanced auto parts fuel pump. (Not sure of the quality)

Can the pump be bad, or not getting enough voltage to crank out enough pressure?

Can anyone give me ideas what else I can test or replace before trying to replace the fuel pump again. I did not enjoy that.

Thanks a lot.

T. Smith

I know nothing about what fuel pressure is supposed to be or how to measure it, but if you know it is low, I suppose that rules out air filter and intake.

have you checked the fuel filter to see if it has unrestricted flow?

clean or replace the injection ports?

remember the fuel pump only runs when the engine is running except for when it runs for 2 seconds when the key is first turned on to prime the system. the proper way of testing fuel pressure is to cycle the key a few times for the fuel pressure to build because just two seconds it not enough time to build full pressure. is this what you are doing?

also, don't forget about the fuel pressure regulator

Yes this is pretty much what I did. I turned the key on/off several times to get the pressure to build to it's highest point, which was 30 psi. tried to start the car too. still 30 psi.

I have not inspected/test the fuel pressure regulator. So, if it is malfunctioning, it can make the psi seem lower?

If I go to the trouble of taking out the injectors and testing them, I might as well remove the fuel lines front to rear and blow air through the lines to clear out debris.

I really don't see any test procedures for the fuel pressure regulator. It looks like it has an internal diaphram. How should I test it?

Thanks.