DaveInDenver

Is it possible for a FPR to fail and not leak? I know there's a diaphragm and a spring inside them, so maybe they can wear out to the point that they no longer operate smoothly or hang up? It seems searching the archives that bad regulators previously either smell like gas or there's a leak into the vacuum port, neither of which I have.

Occasionally my idle falls to a very low RPM (about 500 RPM) and the engine seems to be struggling to run. When I pull the vacuum line off the FPR, it smooths out and comes back up to the idle set point. Sticking a vacuum gauge on the hose from the VSV shows I have OK vacuum, about 14 Hg. This morning I left the vacuum hose off the FPR and plugged for the drive in. The idle always returned to my set point, it seemed to solve the problem completely.

This all makes me think that my FPR isn't working right, but before I go down the path of getting a fuel pressure gauge or a new FPR (or I guess maybe a fuel pump potentially) or something, just wanted to throw it out there and see if anyone else has come across this.

84sr5yoty

The check ball could be hanging up in the FPR or not completely sealing. Also, 14 hg vacuum is too low to be normal for engine vac. It sounds like you have a vacuum leak or an EGR valve that is slightly stuck open.

I think you're using the "band-aid” effect of richening the mixture (removing the vacuum line to the FPR richens the fuel mixture) to solve your low idle issue. It’s always best to get to the root of the problem and fix it.