Soaking a FI assembly to dissolve crud?

Are you sure you're measuring the fuel pressure correctly? If the spec is a "dead-head" measurement and you're measuring at idle, your measurement will be low because the fuel pressure will drop with increasing engine vacuum.

It sounds like you have a throttle body injector with a built in regulator. Why do you think "crud" is the source of the problem? If it's vacuum operated then perhaps the source of vacuum is leaking. Otherwise perhaps the internal spring is weak or the diaphragm is ruptured. No solvent is going to fix these conditions. I think I'd put the junk yard assembly on and see how it works before I started playing around with the original one. If the junk yard one works OK you can take more aggressive action with the old one, but it sounds like a mechanical malfunction.

If he is measuring at idle, which I think he is, that should sound right. How will vacuum increase at idle? Not sure what is "dead-head." Indi

If the vacuum is leaking wouldn't this increase his fuel pressure? It's a good idea to replace with the salvage yard, but someone should explain why three out of four FPR I got from the salvage yard, sitting there for months dry of fuel, won't work - zero PSI. But the one that worked came from a car has pressurized fuel still on them. I got squirted. Ab

The gauge is built into the dash, but I forgot to give the full-throttle reading in the original post. The reading at full throttle (zero vacuum...I also have a vacuum gauge) is 23 psi...the bare minimum. I've checked the line repeated times for leaks and haven't found any, nor any smell of gas leaking.

The car activates the fuel pump for 5 seconds and pressurizes the fuel line when the key is in the ON position, just before I crank and start. When the pump is working, and the car is OFF, it temporarily reaches 23psi, then comes down and stays at 17. When I pinched the fuel return line with vice grips, it rose to about 30psi. During accelerations and decelerations the pressure ranges between 17 and

Dan

Are you checking this with the engine running, or Key On Engine Off? Most specifications are for KOEO.

You also don't mention any type of problem that you are trying to correct. Are you just curious? Year, Make and Model would help.

Unless it says otherwise, the spec is probably for fuel pump running and engine NOT running (zero vacuum). That will probably be a bit more than at WOT because of the lack of fuel demand bringing the pressure down somewhat despite the regulator. If the spec is 23-30 psi, that sounds alright to me..