89 Renix 4.0 Vac issue, an odd one.

[Kenosha Warrior]

I unplugged the vac line running from the Intake Manif and going to the Fuel Pressure Regulator on the fuel rail, right at the front of the motor. If I plug the manifold nipple with my thumb, it idles like crap and bogs down with any load on the motor. If I leave it open, the jeep runs like a raped ape.

 

What gives?

[carnuck]

With the line off, fuel pressure shoots up. The vacuum leak makes up for the excess fuel being thrown in. Same thing happens with the 2.5L and a crack in the map sensor hose!

 

Fuel economy becomes 3/4 of normal.

[Kenosha Warrior]

So my pressure regulator is fawked?

[carnuck]

No. The regulator needs to be hooked to vacuum to work right!

[Kenosha Warrior]

But though, if I connect the reg. to the vac port. The jeep runs sluggish, won't accel at ALL, sputters and stumbles through all gears and I can't give it any throttle if there is load on the engine.