91 Explorer hard start and stall

[Brandonufchoward]

I have a 91 Explorer 4.0 XLT that will not start unless the throttle is floored to the floor. Once the throttle is released the engine dies and I can not keep it running unless I keep my foot on the gas. I have replaced plugs,wires,fuel filter, and fuel pump. Fuel pressure checks ok and does not bleed down on the gauge although there seem to be a small trace of gas on the vac line to the fuel pressure regulator. I have also replaced the idle air control valve and mass air flow sensor with another known good unit. Still no luck. The battery is dead from extended cranking so I have to put a jump box on it to get it cranking. I hook my scan tool up (Solus) to the vehicle it will show live data but wont pull the codes for some reason. I thought maybe because of the dead battery the codes got cleared but if I jump the vehicle and keep my foot on the gas the vehicle will run and the check engine light will come on. Any ideas of where to go from here would be appreciated. Thanks!

 

[BrooklynBay]

The fuel pressure regulator has a leaking diaphragm, and needs to be replaced. I've deleted your other thread since it's a duplicate of this one. Please don't make multiple threads on the same subject.

 

[marragtop]

Have you checked for vacuum leaks at the vacuum tree?

 

[Brandonufchoward]

Thanks for the response. I will check the vac tree for leaks am I safe to assume that it is located on the side of the upper intake by the idle air control valve?

 

[marragtop]

The vac tree is located drivers side top of engine by the firewall.