Hey All, 1991 348 Was driving on hot day for about an hour. Fuel gauge was flipping between 1/4 and empty so I went to gas station. For about 30 seconds high pressure was coming out of filler cap. Then I held the nozzle in the filler pipe for about a minute until no more pressure release. I can’t locate the fuel tank relief valve, in the car or on diagrams. Any advice? I assume it just needs cleaned. Is it #21, anti evap valve? https://www.scuderiacarparts.com/part-finder/ferrari/348/oe/4/7/276 Sent from my iPhone using FerrariChat
ROV # 5 on the diagram. #21 is the opposite it causes the fuel tank to crush in on itself. I replaced mine for good measure. https://www.ferrarichat.com/forum/threads/348-anti-rollover-valve-anti-tilt-valve-replacement.453019/
Dude! Thanks! I’ve been cleaning mine. Hooked them up. Seemed to be working. Couldn’t figure it out!! (#21) For other people, here are compatible parts for #21 versus $500 on scuderiaparts Image Unavailable, Please Login Sent from my iPhone using FerrariChat
Got a part number for 80’ Sentra? Assuming you mean the anti tilt valve (#5) Wouldn’t evap valves (#21) still prevent gas from getting to charcoal canister then getting to the anti tilt valve (#5)? Anti tilt valve seems to be working fine…. Ball rattles and I can blow through the black bottom and air comes out the white top. I can blow from top to bottom too, with less resistance. Not sure what that means! There was white powder corrosion in the lower hose of the anti tilt valve that goes to the fuel rail thing under the rear window. I cleaned that line out. Sent from my iPhone using FerrariChat
So it’s still building up pressure after I cleaned the anti-tilting valve and anti evaporation valve. The anti-tilting valve allowed me to blow air through it both directions. The ball shook well in it. White part is up and black part is bottom. The evaporation valves only allowed air through one way. They let air in one way when no power was to them. When I put power to them, I heard them actuate. I cleaned it all with MAF cleaner and then WD40 and blew it out best I can. Further thoughts? Start throwing parts at it? I replaced the fuel vapor line to the anti-tilting valve and the hose from anti tilting valve to ash canister to ensure no blockages. Sent from my iPhone using FerrariChat
So I went through the exact thing you're going through....cleaned, troubleshooted blew through valves, etc, etc and I still could not keep the pressure from building up. Then I read about the opposite phenomena which is a vacuum occurring which actually implodes the fuel tank and essentially ruins the fuel tank causing cracks and leaks which usually requires replacement! So I took the ninja approach and I actually leave the gas cap ever so slightly loose.... no more problems with pressure and certainly no possibility of vacuum!
Just thought I would chime in on this thread. I have been chasing a hot start problem for years. Hot start problem meaning it sounds like a metal coffee can full of marbles when trying to start hot so naturally I did the clutch repack thought that would fix it it did not then I did the fuel pressure regulators that did not help then I decided to replace the crank position sensors but before I even got them installed I had this fuel pressure problem and started leaving the cap loose. Now it doesn't have a problem hot starting anymore. ....at all. My theory is maybe the pressure was so extreme that it was flooding the engine from back pressure and pressure drop in the fuel injectors I have not installed the crank position sensors at this time and don't really plan to because the problem seems to have resolved itself. Ps Previous owner had the auxiliary starter relay mod but that never really was an issue with this car.
