rpms race then drop - low gas?

[jdusty4]

today I was driving in brooklyn, very stop and go, but temp reading normal. suddenly the rpms started racing up to 2k, then dropping down, then racing up again. this would happen in idle, but also in gear, i.e. if i was in gear and below 2k rpms (this was disconcerting). I was low on gas - 'range indicator' said 26 miles left - and so I drove to a station and filled up. I started up again, the rpms went to normal idle @ ~600, raced once to 2k, and then went back to 600 and stayed there with no problem. Drove home, about 3 miles, with no problem.

Is it possible that this was due to being low on fuel? I've driven down to ~9 miles remaining on the range indicator and this has never happened. I'm wondering if there's anything else I should be looking out for.

Thanks in advance for help, checked the archives and couldn't find anything along these lines.

[dnguyen1963]

Why are you driving a 20+ yrs old car with practically fume in the tank? Yes, I know there are guys that drive their cars on fume, but they probably treat their car religiously. I would keep the tank at no less than 1/4. If your car continue to rev after that then I would look for a vacuum leak and check the fuel pump performance.

[bddog]

Idle Control Valve

[TurboJake]

Is it possible that this was due to being low on fuel? I've driven down to ~9 miles remaining on the range indicator and this has never happened.

Holy shit!

















































It goes that low?????!?


(Probably just a vacuum leak man. 99% of M20 surging cases are vacuum leak or a dirty ICV.)

[rodpaine]

Idle Control Valve

Check the Idle Control Module, too. I had one with a cracked solder joint that caused the same problem. Reflowed the solder joint and was back to smooth idle.
-Rod