Giovanni

Usually it does it when driving steady in 5th gear at about 60 rpm. After 10 miles or so the jerking becomes more noticable and it goes into a lean/no power stage. It may be 5th gear or any gear/speed. If I park the car and let it sit for 10-20 minutes it will idle and run fine. Other times I can put 30 miles on it with just the occasional jerking/hesitation in 5th gear but with no powerloss.

I strongly think that all the problems are related to my low fuel pressure. How do I go by checking the fuel system, dampener and regulator?

AO

Sounds like you're creating vacuum in yout gas tank. Try driving without your gas cap on and see if it still does it.

Giovanni

I will do this tonight.

How about checking the regulator and/or dampener?

AO

I can't see how the regulator/dampener would cause a gradual decrease in power. Maybe someone else can comment?

Giovanni

Can they cause a loss of fuel pressure? Check valve?

AO

Not sure. I thought it worked the other way around, where you end up with too much fuel pressure.

I guess the other suspect in my mind would be the fuel filter. Have you checked that?

Giovanni

I installed a new fuel filter 2 weeks ago as well as new in-tank fuel pump. I'll check into swapping the external pumps and see if it makes any change.

Thank you..

bd0nalds0n

The check valve keeps pressurized fuel from backing into the tank after you shut off the car. It probably also reduces pulsing.

I had a fuel pressure regulator fail in the shut position, and caused my fuel pressure to go >99 psi, which was the limit on my digital gauge.

If the fuel dampners fail, you'll dump gas into the vacuum lines and I would think this would be quickly noticed, since you'd pull gas into the throttle body which I assume would be deleterious to performance.

I will repeat that if you're getting 30 psi while you're cruising, you should have ample pressure, and if the pressure STAYS at 30psi, then you should have ample flow. Does the fuel pressure drop and continue to drop as it exhibits the symptoms you describe?

Bill Ball

Ok, I can see how the bucking might be fuel-related but it doesn't sound like a pressure issue. You have enough pressure that it should idle and cruise.

What about the hard cranking? Is it a labored cranking where the starter can only turn the engine over slowly? If so, that has nothing to do with fuel.

AO

Good point, Bill.

Giovanni

Brian, there is no difference in the fuel pressure when the car is acting up.

BrianG

Good call! Since this is an "altered" car, there might be a number of things, and I haven't seen much talk about dealing properly with the fuel tank vent system in S/C threads, here. Certainly the time interval to failure could be pointing in this direction, but if I read this thread properly, things were OK prior to the pulley change.

First thing I'd do is revert to the old pulley and see if the issue disappears. If an issue arises after I've changed anything, I "unchange" it just to be certain that THAT is the issue and not something concurrent.

If it is related to the pulley swap, we can go from there with the brain storming. Personally, I don't see it, but it's the logical first step.

Next step, from what I can see here, is the in-tank fuel pump & filter change...... which actually sounds a lot more likely. Like a fuel filter installed in the wrong direction........
Don't ask why I think this is very likely!

Giovanni

"Like a fuel filter installed in the wrong direction........ "

I'll check that tonight but I will not post to this forum anymore if I installed in incorrectly. Hehhehe

AO

Yeah, I know what that can feel like.

BrianG

It would be too sweet if it's that simple!

And if that's it...... DO NOT turn it around!!!

REPLACE it!