Real Fiero Tech

Couldn't you just plumb the return into the fill line?

Series8217 wrote:Couldn't you just plumb the return into the fill line?

Probably could, but then you would need to come up with a way to do that and then plug the return line. I think I have come up with an easier way to modify the sending unit so air bubbles can no longer travel down the return line to under the pickup sock.

I would like to make a correction about something I stated earlier. The Fiero sending unit's "design flaw" is something I was referring to from a performance standpoint. It was purposely designed that way from the factory for emissions reasons. So in that respect, it was not a design flaw. GM did not want fuel just dumping in from the top of the sending unit onto the fuel below because it could lead to increased evaporative emissions being created.

-ryan

A short update. I have confirmed that I damaged my fuel pump beyond repair. The car is still driveable, but I can't go into boost at all. Fuel pressure won't go above 50psi. I have been in discussion with Ryan about fuel pump choices. I'm not saying that I wasn't happy with the walbro, but I never like keeping things the same.

Ryan had mentioned to me about a supra fuel pump and I did a bit of research and found this thread about a denso 280lph fuel pump for the supra:

http://www.turbobuick.com/forums/genera ... alled.html

After reading through the thread, I decided this is the way I am going to go. When I bought it, they said it was backordered but it's supposed to be shipping out tomorrow. When I get this thing installed I will update with a review on it. AFAIK, I will be the only person running this pump in a Fiero.

I'll be eager for your report on if it really is quieter than the Walbro 255.

Me too, the 255 is noisy noisy. I'm wondering now if I didn't damage mine, guess I'll find out if I ever get it running again.

I'm a bit late to tell my story, but I recently took a 6 hour drive down the central Kalifornia valley in ~110 degree heat (which sucked ass beyond compare). No issues from the fuel pump.

I may, however have a stuck vapor release valve on top of the tank - it get pressurized quite a bit when it's hot out, and may have prevented the problem.

Blue Shift wrote:I'm a bit late to tell my story, but I recently took a 6 hour drive down the central Kalifornia valley in ~110 degree heat (which sucked ass beyond compare). No issues from the fuel pump.

I may, however have a stuck vapor release valve on top of the tank - it get pressurized quite a bit when it's hot out, and may have prevented the problem.

There is no vapor/pressure release valve on top of the fuel tank. The excess pressure & fuel vapors are supposed to be allowed to escape from the tank via the 1/4" vent line to the charcoal canister where they are stored. Then when the engine runs, these stored vapors are purged by the engine. You do not want to allow the canister to become saturated with fuel vapors -- it needs to be purged on a regular basis (as the engine runs).

If you have removed your charcoal canister, then the raw fuel vapors have nowhere to go except to escape from the car via an open vent line unless you have plugged it off -- which you should not do. There is a check valve in the gas cap but it is designed to only let fresh air into the tank; not to allow vapors to escape.

I remember the 3 pipes at the fuel tank hanger sealing disk on the top of the tank. I had a couple crack loose so I ended up torch soldering the pipes back in, which worked great. However, I'm pretty sure that it must have melted or sealed shut whatever allows those tank vapors out, as I found when I did the "suck test" on it after the repair, and by the hiss of escaping pressurized vapors every time I pull the gas cap. I'd have to pull the tank AGAIN to fix it so I've left it alone for now.