weird high idle with nearly empty tank Options

[dax1969]

Hi,

I have a 74 2.0 FI and car idles, after warming up, at a normal 850/900 rpm

Yesterday however I had something weird ... In the morning (really cold outside) everything was normal (higher idle on start up, normal idle when warmed up)
but on the way back the idle remained at 1200 rpm. I immediately thought vacuumleak.

I needed gas as I was running very very low on fuel (warning light came on, never saw it before (IMG:style_emoticons/default/biggrin.gif) ) ... fyi, my tank is shiny and clean as I cleaned and coated the tank last year.

After filling up the idle went back to normal... Drove the car again next day, same...all normal.

Can low on fuel cause a higher idle ?

weird

cheers
Dax

[76-914]

AFAIK that is normal. While I've had my '76 down for body, paint and general restoration I've kept ~ 1gal of gas in the tank during this period. Needless to say it's run out several times and I just add another gallon. When it is just about out and at idle it will pick up the rpms. It really fooled me yesterday after I had gone through the fuel system, adjusted FP, air adjustment on TB and idle control on ECU. Got it to idle @1000rpm with no surge or hunting and was quite pleased with myself. one minute later the RPM jumped to 1200 and I started fiddling with everything again to no avail. Fuel pressure had dropped from ~39psi to ~36psi. (IMG:style_emoticons/default/WTF.gif) Then it dawned on me to look into the tank and lo & behold it was running on fumes. Added another gallon and Bob's your uncle. (IMG:style_emoticons/default/beerchug.gif)