BlackHawk

iTrader: (2)

It looks like I am having a small fuel pressure problem here...

I fried one of the wires to my fuel pressure gauge a few months back and it took a while for me to get around to fixing it. About 2 weeks ago the car seemed to start stumbling a bit as soon as the boost would start to come on so I figured it was time to get that gauge working again. Rewired the damn gauge and discovered that my fuel pressure was really low, down about 53psi at idle and dropped down closer to 45psi under throttle . Immediately checked the 20A fuse to the Vortech provided secondary fuel pump and discover that it was popped. Put in a new fuse and the idle pressure went right back up to 60psi... Great!! Easy fix right???
Not quite.
The car still seems to stumble a bit with boost, just not as bad. And now when the boost starts to build at about 5psi the fuel pressure still starts to drop. Under full throttle it will drop from 60psi down to about 57-58psi or so... Only a slight drop but, I don't remember seeing any pressure drops at all before. This wouldn't normally bother me but the car does feel like it's running crappy still.

So...
1. The stock in-tank pump that's still in there (80k miles) is giving up? If so what should I replace it with?
2. The fuel pressure regulator is starting to go? Is there something better out there to replace it with?
3. The secondary pump (in line boost a pump) starting to go bad?

Any ideas or insight here?

DeltaT

iTrader: (5)

I'd start by checking all your plugs for any sign that you damaged something while you were running with low fuel pressure. Don't assume anything - it may not be your fuel system. A 2-3psi drop under boost shouldn't give you any running problems.

It also may be worth doing a fuel volume-in-time test, to make sure you are not only getting fuel pressure, but the right volume of fuel through the system.

What blower, etc. are you running?

Jim

BlackHawk

iTrader: (2)

I pulled 2 plugs last week and though a little mucked (badly in need of a catch can) they really didn't look bad. The electrodes looked fine and gap was still .40... Nothing melted down, just a little burned carbon like coating on the outer edge and threads. But I do plan on swapping a new set (TR6's) real soon, along with a catch can.
The car isn't running horrible, just doesn't feel like it's at 100% either. I'm just a bit worried from that fuel pressure needle movement that I never saw before... Heck I just about had a heart attack when I saw that I had been driving without the secondary pump for about a week.
Blower: Typical Vortech V9, 2.75" pulley seeing about 10psi of boost (lowered compression.)

DeltaT

iTrader: (5)

Check all 8. I know it's a pain but you gotta start somewhere, and with FI the plugs come first, unless it's something obvious.

Are you using the A2W intercooler?

Jim

Got Me SOM

iTrader: (2)

definitely change all plugs. look at your wires too for good measure.

dropping down to 57 isn't bad. check your fuel filter.

mine goes from 60 psi at idle to like 53 psi and I have a Racetronix..Now I know there's something wrong there but haven't figured it out...Maybe I need a fpr..

andereck

Check the wiring all the way to the pump for chafing or water corrosion. Check your ground and take it off and reinstall it if necessary. Your inline pump is probably not getting full voltage. That pump should never draw 20 amps and pop the fuse. An Aeromotive A1000 wouldn't draw 20 amps at that pressure and it has a helluva lot stronger motor than that.

BlackHawk

iTrader: (2)

Yup still the stock A2W inter/aftercooler.
Yeah... The plugs are a pain, though I gotten pretty good at it. I was planning on taking next weekend to just swap them all out again and maybe close up the gap a hair to smooth things out a little.

Actually took another look at my fuel pressure gauge and I am actually dropping down to about 52psi under full throttle... (Ooops, forgot that the hash mark on this tiny Autometer gauge is not 55psi but 50psi )

I think while I am at it I am going to take andereck's advice as well and check out the wires to the pump. Popping that fuse does concern me a bit.

I changed the fuel filter, no change.

I guess what really bothers me is that prior to me frying the wires between the fuel pressure sensor and gauge, my fuel pressure gauge acted more like an idiot light. Fired the car up, and it would stick at 60 psi and not move at all for nothing until you turn the car off again. Now I am seeing a bunch of movement there.