no fuel pressure vacuum

[daveyfx]

So I noticed this problem after installing my boost gauge...

On cold starts, I have noticed that there is vacuum going through the hose from the manifold to the fuel pressure regulator solenoid. On hot starts, however, I will have no vacuum at all for several minutes and then I will get a normal vacuum readout.

What could be causing this? On a side note, the car runs like crap (very flat, linear feeling powerband).

Thanks in advance!

 

[robs90tsi]

Sounds like you may have a boost leak as a result of installing your boost gauge. Did you make sure that you didnt kink the nylon line at all?? Did you install it correctly?? I think that since this started happening after that gauge install, that is your problem. Do a boost leak test, or, re-do your boost gauge and make sure you do it right, not kinking any lines or anything like that.

 

[daveyfx]

What I mean is that the actual hose running from the manifold to the solenoid is not creating any vacuum. I know there's no kinks in that line as I can literally remove the vac line from the T fitting (to the boost gauge) and wait a few minutes before I feel vacuum.

I thought it was a leak or a kink at first too until I ran a very short vac line from the T to the gauge by routing it straight from the engine bay, through the window, and connected straight to my gauge. There were zero kinks in this line and I got the exact same problem.

Any other ideas?

 

[steve]

That's what the Fuel Pressure Solenoid is designed to do. Are you sure your doing whatever to the correct side of the solenoid. The FPR gos the the side of the solenoid that is switching and the other side goes to manifold and boost gauge.

Steve

 

[daveyfx]

I have it T'd on the hose from the solenoid to the manifold. There are two hoses if I remember correctly. One is solid black (manifold to solenoid) and a black with blue stripes (solenoid to FPR). My T is inline with the solid black hose.

 

[steve]

I find it very hard to believe thet you don't have any manifold vacuum on hot starts.
I can believe that you hooked up the hoses wrong or a PO did and now you have a vacuum leak

Try taking the FPR solenoid out of the circuit. connect the manifold to the tee for the boost gauge and then to the fuel pressure regulator.

Steve

 

[daveyfx]

It was definitely hooked up to the correct vacuum line. At any rate I bypassed the solenoid and it works much better now.

 

[steve]

If you bypassed the solenoid and it solved the problem then it sounds like somehow the hoses got connected to the wrong nipples on the solenoid causing it to vent the intake manifold to the atmosphere rather than venting the FPR pressure reference.

I wasn't talking about the boost gauge or it's tee.

Steve