Fuel Pressure

[dave92tsi]

Alright here's the deal, I had some fuel pressure problems they would fluxuate alot, one thing i did notice is when the car was turned off the pressure would drop to 0 psi immediately, as for other cars i saw that held pressure on the fuel rail. could this be a bad pump or o-ring? it's a walbro 255lph, oh yea it's not a electronic gauge it's mounted to the fpr.

 

[dave92tsi]

i guess what im asking is does your car hold pressure when turned off? what fuel pump are you using?

 

[jpolizo]

Is the car hard to start after it sits for a while? You would expect that if it were bleeding off pressure.

Another cause of fuel pressure bleed can be a leaky injector (i.e. it's not closing).

 

[dave92tsi]

yes it's a pain to start, dosen't really matter if it sits for a long time or for a few minutes

 

[Awdboost]

Somethings wrong with you Injectors or Fuel pressure regulator. Your pump is doing it's job fine.

 

[whitegst97]

I have a similar problem, hope someone could give me some info on this. I dont' know if i should disconnect the fuel pressure solenoid and connect the FPRdirectly to the manifold, i've heard is better, i really don't know. The problem than experiencing is that when the car is still warm or i try to restarted after a recent shut off, (not like the next day) It starts but like a rotary engine, it doesn' start normally and idles at 800 rpm or so immidiately, it starts and the Rpms start really low like at 100 or so and then build up. It starts low as if it were going to turn off and then rises to normal idle. If i turn it off and start it the next day it starts normal, like accelerates to 1300 rpm and settles to the normal idle. What could this be. thanks a lot for any help.

 

[workin_on_it]

if your injector is leaky, after you start up the one cylinder will have lots of gas stuck in it, causing a big puff of black out the exhuast pipe. this just my theory.....someone back me up here.

 

[dave92tsi]

so is it safe to asume that the car is supose to hold fuel pressure

 

[jpolizo]

Originally posted by dave92tsi
so is it safe to asume that the car is supose to hold fuel pressure

Yep, that's why the service manuals always tell you to bleed it off before you do anything with the fuel system. If it's bleeding down, then it won't start for beans.

 

[halvorja]

Some people have problems with the Aeromotive fpr (like me too). A guy on the DSMTalk forum actually called Aeromotive to see why the fpr won't hold pressure after the car is shut off. They told him that the ball inside the fpr is so large (since it flows so much) that it doesn't completely seal.

Now, you may think this is a bad thing, but just realize that every time you crank away on the car, you are doing the engine a favor by priming it with oil before it starts up. That's how I look at it.

Jake

 

[jpolizo]

Originally posted by halvorja
Some people have problems with the Aeromotive fpr (like me too). A guy on the DSMTalk forum actually called Aeromotive to see why the fpr won't hold pressure after the car is shut off. They told him that the ball inside the fpr is so large (since it flows so much) that it doesn't completely seal.

Now, you may think this is a bad thing, but just realize that every time you crank away on the car, you are doing the engine a favor by priming it with oil before it starts up. That's how I look at it.

Jake

:laugh: Must be a division of Microsoft! It's not a bug, it's a feature!

 

[whitegst97]

Can someone give me their experienced opinion here, i wanna know if disconnecting the Fuel pressure solenoid will be benefitial in any way , i heard that connecting to the manifold will allow the car to run on a 1:1 ratio of air an fuel, meaning that if the psi is increased then the fuel pressure will be too. Correct me if im wrong. Should i connect it directly or leave it as is.