mooner

I have a 94 Formula and the car starts fine idles a little low and when i get on it it flies but when i let off it floods and dies. The only way to start it after that is to put the gas peddle to the floor and once it starts i have to keep it over 2000 rpm or it dies. After about 3 or 4 hours it starts back up normally. Ive had a new o2 sensor put in and please help me figure out the problem. Im guessing fuel pressure regulator. PLEASE WRITE BACK.

Injuneer

Could be many things, including the fuel pressure regulator. That's an easy one to check, simply by attaching a fuel pressure gauge. Could also be related to the O2 sensors.... you have two, but apparently only changed one?

Could be a problem with leaking injectors, faulty idle air control (IAC) valve, maybe even a faulty coolant temp sensor, MAP sensor or throttle position (TPS) sensor.

I'd check the fuel pressure first. At warmed up idle, with the vacuum line removed from the fuel pressure regulator (FPR), you should see 43.5psi..... factory specs allow anything from 41-47psi. While the vacuum line is off, check it for wet fuel or strong fuel odor - indicative of a failed FPR diaphragm. Reconnect the vacuum line and the pressure should drop in proportion to intake manifold vacuum, or a drop of 6-8psi with a stockish cam.

Then take it out on the road (tape the gauge to the windshield) and watch the fuel pressure as you drive. At WOT it should be very close to the pressure you measured with no vacuum line connected.