Intermittently high idle speed, 1992 4.0 V6.

[Fast Doc]

William shared 1 photo with you

www.amazon.com

This is the end of the hose that I am pretty sure was supposed to be on the mystery part.

 

[Fast Doc]

William shared 1 photo with you

www.amazon.com

Does anybody know what this thing is that I am pointing to?

 

[RonD]

It is the FPR(fuel pressure regulator)
Thats a direct vacuum line to intake so would be a vacuum leak if disconnected

The Return fuel line is attached to FPR as well

The spring inside the FPR is set for 42psi fuel pressure

The vacuum line causes pressure to drop to 32-35psi with engine running, as vacuum pulls on springs diaphragm
When you step on the gas, the vacuum drops and demand for fuel goes up
So this helps to keep fuel pressure at 30-35psi so computer doesn't have to adjust injector open time as much.

 

[Fast Doc]

Thank you for your time and expertise.

I'll change the sensor if this has not fixed it; you were a big help have a great day.

Bill

 

[Fast Doc]

A little feedback if it helps anyone else.

The issue was intermittent and returned worse than before and was very frustrating. I threw in the towel and brought it to a mechanic. He replaced the throttle position sensor and that fixed the problem. I didn't even see a TPS in the shop manual. Oh well...

 

[RonD]

Good work

Thanks for the update and the FIX