I think I may have figured this out but for your entertainment and puzzlement try and identify the sound in this video. The video was taken near the fuel pressure regulator and pre filter plumbing. After the ignition is turned on you can hear the fuel pump getting up to pressure, a relay click and then ... what the hell is that sound? Fuel pressure is regulated to 60 psi for the Sniper Quadrajet and you have to wait a few seconds for pressure to build up and the ECU to initialize. Like I said - I think I got it figured out but won't know for sure until the next start up. The recording plays twice but the sound only happens once on start up and if I'm correct I should not hear it again Bob
Fuel system being filled is the steady 'whirr' sound then a couple of seconds as it is achieving operating pressure 'the slight change of 'whirr', then the 'r2d2' sound is the fuel pressure regulator relief initial lift off the seat and then fuel pump cutting off, as it has not received the 'ok to run' command from the ECU (either based on oil pressure from cranking, or by sustained RPM from engine continuous rotation). If the fuel pump were to continue to run with no fuel usage, the regulator would continue to 'cry'.
Steve - I think you nailed it for what it making the noise. However it never did it in the few months since adding the Sniper and did not do it yesterday after sitting a while and my having fixed a slight leak. After hearing the sound I checked under the hood and discovered a very slight fuel leak. No more than a damping under the pre filter. Narrowed this down to the NPT to AN adapter at the outflow of the filter. After removing this re-applying Earls thread seal and refitting no more leak no more sound. I'm not sure of the mechanics of the sound but it would appear that the pressure drop caused by the leak after the pump shuts off was the cause. Cheers Bob
