Jumped on the highway today and got up to speed (70mph). After a minute or two of cruising I noticed my fuel pressure is down to 3-4psi! Once I exited and came to a stop it only went back up to 5-6. When I first start the truck it's always around 9-10psi, but once it gets pulled down to 6psi it seems to pretty much stay there. This is with the Smarty on #5, but that shouldn't matter too much because I was only cruising at the time. The fuel filter was just changed less than 500 miles ago.

Is this normal? Seems way too low considering I wasn't anywhere close to WOT.

 

Have seen it down to 1.8psi now under heavy throttle. I wonder if the 7 micron filter is causing the restriction?

Is there an aftermarket pusher pump that can be installed without dropping the tank? Is it possible to just tie into the stock lines to avoid dropping the tank with the GDP 392 setup?

 

What is the location of your pressure tap?? Even with a new filter you can take a slug of dirty fuel and plug it up. I would change the filter again to see what the pressure is doing. Save the old filter as it may still be usable.

 

Thx for the advice. I'll go ahead and change the filter again and see if that helps.

The pressure sensor is located at the banjo bolt in the bottom of the filter canister. AFAIK it should be a post-filter reading in that location.

 

I've modified my banjo bolts to be high flow (drilled the side holes to 13/64). That helped on full throttle runs to keep the pressure up. You just have to be make sure that you file, clean, debur everything so that it doesn't get into the IP or injectors. Or you can also buy them.

 

On my truck I normally run 9psi at idle and between 6-8 psi cruising at 65 mph, that depends how I have it programmed.