Fuel pump or injectors or normal

[channer]

I've got a fuel pressure gauge on my car which I have been monitoring.

After I've been driving for a while (30+ mins), and the motor is nicely warmed up, I've notice that I loose about 2-4# of fuel pressure (at idle)... and also the needle seems to shake/shiver between 1-2#.

Is this a normal?? is it a problem with fuel pump or a problem with injectors?? Or voltage (showing 12.8-13.4 volts when stock fan comes on)

I've been trying to figure out my ongoing highway hestitation/stutter & die problems?? (sorry no gauge when car died... but the car always restarts after a cool-down). I was thinking that the fuel pump gets worse the longer I drive!!! I've changed coil/module& MAF already!!!

I have 3 year old walbro 307, hotwired, adjustable FR, stock injectors & a brand new fuel filter.

thanks

 

[UNGN]

Fuel pressure is proportional to engine vacuum/boost.

If vacuum fluctuates, so will fuel pressure.

Sounds like you may have a vacuum leak.

 

[Crazi]

Or you could have what I had. I was trying to figure out the same thing quite a while ago and it turned out to be a billet fuel pump adapter from ATR. The owner who had the car before me put it in and the silicone seal or whatever had ripped and was flapping around inside the adapter. Luckily it didn't get up into line and stop flow altogether. I pulled it out when I put in the 340 and used regular fuel line.

Mine would fluctuate about 3-4 lbs. though so you may have vacuum fluctuations. I know that when your car misses, it will show as vacuum irregularities.

 

[blackbuick87]

When the car dies all you have to do is pull a plug and turn the motor over and see if you have spark. If you do it is the fuel pump.

The pump could be getting hot and shutting down