mike_c

iTrader: (13)

I've been having an idling issue and I think it may be a result of a fueling problem. The idle used to surge intermittently but now it does it nearly all the time. I did some fuel pressure tests tonight and here's what's going on.

• With the fuel pressure gauge hooked up, I primed the rail and pressure goes to 45 psi and then bleeds off to 0 pretty quickly.
  
• While building pressure in the rail, I pinched the supply line and it held pressure longer this way, but still bled off pretty quickly. This would lead me to believe there is a leak in the tank or a bad check valve in the supply line?
  
• Again, while building pressure in the rail, I pinched the return line and it held pressure. This would mean that fuel is leaking past the regulator, correct?
  
• I also pinched the return and supply lines while the rail was pressurized and it held pressure in this state. This would seem to eliminate the injector(s) as a leak.

All these tests were done while jumping terminal G on the ALDL with 12v. I also haven't checked to see what the fuel pressure is doing with the car running yet because it was too late in the evening to fire it up and I didn't want to tick off the neighbors.

mike_c

iTrader: (13)

I should also add that I replaced the fuel pump last year with a Walboro 255 and I reused the old pulsation dampener because I didn't know any better. After doing some more reading on the boards, I'm beginning to realize how big of a mistake that may have been. I have a feeling I'll be dropping the tank again to delete the dampener

mike_c

iTrader: (13)

At idle it's at 40 psi. Cruising it's at about 38 psi. Deceleration in gear it drops to 35 and WOT is 42-45. Any ideas what's going on here?

TTOP350

iTrader: (8)

The vaccum or lack of is changing PSI like it should.
Really, it should hold PSI but as long as the PSI comes up when you hit the key, you are fine.

mike_c

iTrader: (13)

So you think the surging idle I'm having is unrelated? It's gone from doing it once in a while to all the time in a matter of a couple weeks. How long should the rail hold pressure? It bleeds down to 0 in a matter of seconds.