Liquid filled fuel Gauge/AFPR ??

[spadepro22]

The liquid in the gauge has leaked out and the pressure drops instantly when I shut the car off. It holds the correct psi tho. Could the gauge be the problem or AFPR? I took it apart and the diaphragm is fine.

 

[curt-s]

Lots dont hold pressure. It may not be the afpr that can't hold after you shut off the pump. Hell, do all pumps even have a check valve in place? If it still rises 1:1 then there is no sense changing either part.

 

[Black95TSIawd]

Check the o-ring is on your fuel pump assembly or your gas cap.

 

[Lazyboy]

The purpose of the liquid filled fuel pressure gauge is to keep the needle from bouncing around when the engine is running, kind of like a damper for the needle.

 

[Chumpaumpalumpa]

The purpose of the liquid filled fuel pressure gauge is to keep the needle from bouncing around when the engine is running, kind of like a damper for the needle.

Can't you just fill it up with mineral oil or something if it leaks out.

 

[Lazyboy]

Not sure about that, I would just buy another one, they are not too expensive.

http://www.summitracing.com/parts/sum-800199

 

[spadepro22]

Lots dont hold pressure. It may not be the afpr that can't hold after you shut off the pump. Hell, do all pumps even have a check valve in place? If it still rises 1:1 then there is no sense changing either part.

How do I check to see if it's rising 1:1?

 

[curt-s]

thats the rub. you cant unless you can see the gauge while accelerating.
however it suggests (but doesnt limit to) a faulty afpr, pump, or injectors if you have hefty inclines in your mafcomp or ve as boost pressure increases based on wideband readings. that means you have to feed it more fuel than it thinks you should need to at that particular rpm and load. ve naturally increases smoothly to a point so you would instead see sharp inclines.

conversely if the afpr was overshooting pressure, you would have drops but the curves would likely look less dramatic i would think.

 

[cjridert1]

If you base pressure is 43, and you put 40 psi on the vacuum line going into the fpr (bike pump, air line, whatever), then you will see the fpr gauge go to 83psi, providing your pump is on.
Do this with your car off, acc on. You only want the pump on. You could wire it on if you don't have dsmlink.

Probably easier than looking at trends in logged values, and making guesses.

 

[steve]

Keep in mind that liquid filled gauges can display incorrect values as they heat up. The oil can pressurize the inside of the gauge and effect the bourdon tube that drives the needle.

Many AFPR's have been noted to not seal the return oriface well which can cause the residual pressure to drop quickly when the pump shuts off. Assuming a healthy pump (and seal at the pump) the fuel pressure should quickly recover on startup and not be an issue.

Some people have torn the AFPR apart and found burrs on the oriface seat causing the issue.