S13 bad fuel pump? need help...
 

So my '90 s13 has a ka24de swap and yesterday the car was driving fine and all of a sudden it's started to jitter a bit then it would just die unless i keep pumping the gas, now the only way the car starts or stays on is if i keep pumping the gas non stop what could it be? Fuel pump? I haven't don't much work to the car yet. People suggest clogged fuel filter, bad fuel pump, fuel pressure regulator, or AIC.

If you suspect fuel disconnect a fuel line off the top of the filter an see if it sprays fuel...sounds more like cat or head gasket to me...check your oil and water too

Why would it be a cat? >_>"

It is likely a fuel issue. rent a (free) fuel pressure gauge from local autozone to verify if the pump/filter/regulator is at fault.

Otherwise, (next) unplug the maf sensor and diagnose the electronics involved with fueling the engine.

Also:
1. cat is mentioned because they tend to clog, and a clogged cat gives a symptom of an engine dying
2. It wouldnt be the IACV (idle control valve) because the throttle body (throttle valve, "gas pedal") overrides that

without seeing it, most likely it is your fuel pump ( the pump is probably ancient, failrly common failure), followed by a clogged filter(unlikely) or wiring related (maybe the maf ground came loose. Maybe the maf itself came loose and unmetered air is entering the engine). Inspect all tubes that lead from the maf to the engine before taking anything apart.

Yea I got the car to turn on and we disconnected the maf sensor and sure enough it stayed on but my rpms won't go past 2500, so I'm guessing my sensor most likely went bad right?

Check the rubber hose between the fuel pump and the pump hanger assembly, these rupture eventually especially with the age of the car. I thought I had a dead pump and it was just that small fuel hose that popped.

Probably broke an oring on an injector. Mine was the same symptoms.

If you notice the engine will run fine with the maf disconnected, but not when it is connected, then your first priority is to boost leak check the plumbing. Look for any clamps missing and torn unions between the air filter and throttle body. If this system is pressure tight (boost leak checked) then you should try another maf sensor.

Or if you have a tune on the ECU like a ROM tune the board might be loose. That happened to me twice and acts like I dont have any sensors hooked up and runs like dookey holes