nowcom

Hopefully one of you Jeep experts has experienced and repaired a stalling routine after 15 seconds from engine starting.

Recently I purchased a 93 ZJ - 5.2L that was stalling after just 2 seconds. That problem turned out to be the factory alarm system being

triggered by a faulty rear tailgate latch. The alarm system has been repaired and works perfectly.

The fuel filter has been replaced and while under the car, it appeared that the fuel pump was also recently replaced.
The air filter has been replaced as well as the battery, the fuel pump relay, air filter and the ECM.

The Jeep now starts but only runs for about 15 seconds, then slowly slows down and stalls, even if I apply for gas.
It seems to run longer as it warms up to normal operating temperature.

If it helps, the fuel pump is ALWAYS on!!!, even when the key is not in the ignition. And the only way to turn it off is to remove the fuel pump

relay or fuse.

There is also a small hissing sound coming from the back right side of the engine, about the location where the gas line meets the fuel rail.
However, there is no gas smell at all.

My next step is to get ahold of a fuel pressure gauge and see if the standing pressure is at least 15 psi or so.
I also want to make sure that the full fuel pressure is at least 47 psi.

That's as far as I have been able to get with this project.

Any and all thoughts would be greatly appreciated.

Thanks again,

Steve

dave1123

Welcome to CF!

First, figure out what's going on with your fuel pump. It should only run for about 2 seconds to charge the fuel rail, then shut off until you crank it. Someone may have hot-wired it for whatever reason. You should look at the BOTTOM of the PDC (fuse/relay box under the hood) for added wiring (like a jumper) or shorts and corrosion.

It sounds to me like the engine is starving for fuel after 15 seconds. Why is the question, especially with the pump running all the time. If I remember correctly, there is a pressure regulator on the throttle body that may be malfunctioning. The hissing may be it returning the fuel to the tank instead of to the injectors.

The only other thing that comes to mind is the intake plenum gasket. On the bottom of the intake manifold there is a thin metal plate that seals it. If that leaks, it can cause the engine to go lean or suck up oil.

Bustedback

Silly question, is there fuel in the tank?

dave1123

Wow! Why didn't I think to ask that? Good one, Busted!

nowcom

Thanks guys for the fast replies.
Yes, there is gas in the tank. Sorry I should have mentioned that first.
I'm off to Lordco to pick up a fuel pressure gauge and go from there.
Here's hoping...
Steve