Fuel pressure regulator

[73john]

I pulled the vacuum line to my FPR let it just sit in the open air without plugging it and drove for awhile. The Ranger ran exactly the same whether the FPR had the vacuum line on it or not. Is this a bad FPR?

 

[Earl43P]

Can't conclusively say.

You could have no vaccum pressure TO the FPR, which would make it run exactly the same. Can you feel vaccum pulling at the line you disconnected?

It also makes me think the root of your entire problem may be a vaccum leak AFFECTING the FPR. I say this because it made no difference that you CREATED a vaccum leak by leaving the line off the FPR, uncapped. Follow me?

The definitive test is to read the fuel pressure at idle, then watch it change as you go WOT (briefly), fuel pressure should increase with throttle application, decrease at idle.


John, it appears that you have been wrestling with this issue since February?

Are your heater controls working?
If you shut the truck off, wait a minute, then select different heat/vent settings, can you hear the dampers move?

Most times, when the FPR fails, fuel pressure stays too high, poor idle, soot in exhaust from running rich, poor fuel economy, etc results.

 

[73john]

There is a strong vacuum at idle when I disconnect the line. The truck runs real well at idle as well as at highway speeds. I can put a vacuum gauge on the line although it seems to be a strong vacuum. Heater and damper doors work great. I'm a bit at loss. I thought the stumble might be caused by plug wires/coils?