Hey Bruce, Good Sunday morning to you. Nothing like a neat Alfa problem to start your day, NASA where are you now? I know they have my resume somewhere!
Anyway, contemplating on this intriguing problem and reading Chris Keen's comment regarding the supposed plastic relief valve attached to the charcoal canister, you know I never knew what that was, I always refered to it as an emissions thingy. But I can't imagine a little thing like that would cause so much back pressure to create the problem you have. You would think it would just blow off, its just held on there by a friction fit into the plastic tube. And as you said, its only supposed to allow air in, not gas vapor out! And if you checked the vapor recovery line back to the engine and all is clear, make sure to also check the steel line where it attaches to in engine compartment, this steel tube runs along the coolant rail above the SPICA filter and gets occluded with rust and junk from the condensed vapor, to the point that nothing passes through it and you might have to do away with it completely. But I can't imagine even that would cause this kind of problem. So if your convinced that the fuel pump is not the culprit, realizing that this single port outlet pump is a perpetual pressure pump, the pump itself has no pressure relief mechanism and the SPICA pump only requires 15lbs./sq.in pressure to operate, the light goes out I believe around 13lbs. Thinking that is it possible for this pump to build up that much perpetual pressure? I don't know. But another thought I had would have to do with the heat created in the tank as you mentioned. I can't imagine a GTV gas tank getting that hot. You guys must run the piss out of those things at Summit for that to occur! What comes to mind is Charles and Boyles law, ironically, Charlestown as it is: http://en.m.wikipedia.org/wiki/Charles's_law But it simply states that as the temperature of gas increases, so does its pressure and volume. So I thought it just might be that the tank is getting so hot, thats its increasing internal pressure to the point thats its causing this problem, and increasing back pressure in the gas line that the fuel pressure light takes longer to come on! This would be one for Spok to figure out. So an idea I had to allieviate this, you either would have to vent air to the tank as you would brakes, from outside air. Or retrofit in an external pressure vent, from the tank, to the outside of the car! Not into the trunk area as that plastic relief thingy would indicate. Or maybe put a battery operated electric fan on top of the gas tank in some way? I think an external vent from the top of tank to the outside of the car maybe the best solution. Or, run it continually with a full tank, not to allow gas vapor in there, never a half tank full as you do. In this economy however, I don't know if that would be practical. Good luck! John T-Mobile, America's First Nationwide 4G Network Sent by Samsung Mobile Bruce Giller <[email protected]> wrote: >Folks, > >On Saturday I did a thorough investigation of the tank's plumbing. The >fuel pressure light would wink out in about 1-2 seconds and the pump >sounded normal (not straining). I made sure that the fuel return plumbing >in the tank was clean by blowing air thru it and hearing bubbly noises from >inside tank (the tank was 1/2 full and the end of the return line was below >surface of the fuel). The two vapor recovery connections on the tank were >clear (blew thru them), and the vapor container's three connections were >clear. I double checked the vapor line inlet valve in that it didn't >release pressure but only allowed air in. The vapor recovery line was >clear all the way to the engine - little volume goes thru this line that's >for sure. And I checked the exhaust system for leaks and there are none >nearby the tank that would cause the tank to heat up. > >I've still no idea just what is going here with this tank. > >As to the different styles of FI pumps that Alfa put on SPICA cars, Wes I. >has a great write up here: >http://www.wesingram.com/SPICA_Fuel_Supply_Diagnostic_Guide_Nov_2004.pdf . > My '73 GTV has the correct 2-port (one inlet, one outlet) FI pump. The >newer models had the 3 ports. > >Bruce > >On Sat, Jul 28, 2012 at 11:53 AM, John Palumbo <[email protected]> wrote: > >> I just thought of something else. If your pump only has one port exiting >> the top of the pump, its quite possible you have an entirely wrong pump for >> that particular car! I mean the newer Bosch pumps for the electronic >> injection cars have only one port exiting the top of the pump. So maybe >> someone swapped-out one these for the old styled original pump that was on >> the car, thinking that it would be more reliable. >> >> T-Mobile, America's First Nationwide 4G Network >> Sent by Samsung Mobile >> >> Bruce Giller <[email protected]> wrote: >> >> >John, >> > >> >My FI fuel pump is the new style with only two ports so there's no way the >> >gas can back into the tank from it. >> > >> >Bruce >> > >> >On Sat, Jul 28, 2012 at 7:18 AM, John Palumbo <[email protected]> >> wrote: >> > >> >> Just a quick thought, I would tend to think it would have something to >> do >> >> with the fuel delivery from the fuel pump. The fuel it would seem is >> >> getting pumped back into the tank, instead of to the pump where it >> belongs, >> >> hense you noticed it took longer for the pressure light to go out. >> >> >> >> If I can recall, the older pumps had three ports on them, one to the >> SPICA >> >> pump, one as a return to the tank, and I think the third was for some >> >> emmissions thing, I'm not sure. I know the the newer pumps had only two >> >> ports. >> >> >> >> So maybe if you had a spare pump, you could try installing it and see if >> >> it does the same thing. Perhaps there is a sort of check valve system, >> >> similiar to that of a diode thats gone bad, it being that alows the >> fuel to >> >> flow in only one direction, to the SPICA pump. The other thought would >> be >> >> to run it with the fuel cap off. But there should be no logical reason >> why >> >> the tank should be over pressurizing. >> >> >> >> John >> >> >> >> T-Mobile, America's First Nationwide 4G Network >> >> Sent by Samsung Mobile >> >> >> >> Bruce Giller <[email protected]> wrote: >> >> >> >> >Yesterday we (David Tallerico and I) attended a Seat Time session at >> >> Summit >> >> >Point track after a too-long hiatus. The weather temp wasn't hot but >> >> >pretty warm - mid to upper 80's or so. It is 1.5 hour drive from my >> house >> >> >there and we stopped in Charles Town for gas. at around 7:50 am. At >> the >> >> >station the car would not restart and we discovered that it was getting >> >> any >> >> >gas for the plugs were dry. The fuel pressure light went out but it >> took >> >> >longer than usual for it to go out; usually after running for a bit, it >> >> >only takes 1 second for it to wink out. I removed the return hose from >> >> the >> >> >SPICA pump and gas was pumped out with the fuel pump on. We 'fixed' >> the >> >> >non-starting problem with starter fluid sprayed down the throats. Off >> to >> >> >the track! >> >> > ..................... -- to be removed from alfa, see http://www.digest.net/bin/digest-subs.cgi or email "unsubscribe alfa" to [email protected]
