Scootertrash

97 Chev K1500 w/5.7. Truck drives fine an normal pace, but if I floor it, it seems like it's not getting enough fuel. More of a hesitation/missing than a bogging feeling. When I check fuel pressure I get 60ish when I turn the key on, but it only stays there for a second and starts dropping till it hits about 10 PSI. If the truck is running the fuel pressure stays at 55ish and doesn't move if I rev the engine. I do have codes for the EGR pintle and the 2 downstream O2 sensors, but that wouldn't explain the fuel pressure problem. I'm taking a guess at the fuel pressure regulator, but don't want to rip anything apart if you guys have something else I should check first.
TIA!
Scooter

98white5.0

I was having a similar problem to the one you're having as well as the truck being hard to start when hot. The fuel pressure regulator did fix the hard-start problem but my problem is still there. When I floor it, it will go to about 4000 rpm then just stay there until I let off the gas. Not going faster or slower. Sometimes when it's really hot outside, it won't go about 3500 when flooring it. We might have kind of the same reason for our problems. I think it's a fuel pump issue.

Scootertrash

Ok this may be a kinda dumb question, but I'm askin anyways! If the fuel pressure regulator went bad, Could it bleed the fuel back to the tank causing the pressure drop I'm getting with the key on and engine not running? It shoud hold pressure like that correct?

98white5.0

It would bleed the fuel into the intake plenum. The regulator is located below the plastic black upper intake. There is an injector unit that looks like a spider. The regulator is on the spider. So you would have to take the black upper intake off in order to access the regulator but it would just bleed off into the intake. Usually when you take the black upper intake off, you will see a clean spot right below the regulator. That is where the fuel is leaking.

Scootertrash

I follow that, but what happens to the left over fuel that has to go back to the tank if the regulator is working properly? The motor can't be using all of the fuel that is sent to the injector assembly or it wouldn't need a regulator. I'm thinking this could be what's causing the pressure drop with key on/engine not running. I am going to change the filter today and if that doesn't do it I will look into the Fuel Pressure Regulator. I will update my findings for future issues like this so people can find it with a search.

The Truck has almost 300,000 miles on it. It got a new motor last spring. I've had that plenum off multiple times. I can do it with my eyes closed now!!!

98white5.0

There is a return line, but if the regulator is messed up, it just dumps the fuel right there and never sends any back or sends very little back.

philbo455

The regulator send excess fuel back to the tank when functioning correctly. Only when the unit has ruptured internally will fuel leak into the plenum.

98white5.0

Just as I said in the previous post. Maybe a little better wording in your clarification though.