F22A1, 5 speed 1992 Accord, 247k miles. No oil burning, clattering, etc.

When the engine is 'cold' and the temps are hot (80+)and humid here in Michigan it won't start. It'll crank fine, and usually after removing the gas cap and putting it back on again, and cranking it for a few seconds, waiting a few more seconds, and cranking it over again, it'll finally start right up, no sputtering. Once in a while the idle seems a little rough though.

On cooler days (70s and less) it fires right up, right away, like it should.

It had a tune up about 2 years/15k miles ago, and currently gets around 28.5-30mpg mostly 55mph driving with some city.

I'm thinking it needs a new gas cap and o2 sensor (as I think the tune up was just ignition parts), and a fuel filter for good measure. Air filter is good and it has a recent oil change.

Any other ideas? Could it be vapor lock (fuel going from liquid to gaseous state in fuel rail)?
Matt

 

Is the interior of the car hot?

Search on the main relay - PGMFI Relay. It is common for these to stop working when it gets hot out. There are a few solder joints that don't work in the heat. If you don't hear the fuel pump prime when you switch it from accessory to run, then change it out.

In some posts, it will let you know which solder joints to re-solder to get the old unit to work. New units are like $30-50 at O'Rielly.

Check to see if the fuel pump will prime and then check back. If it is the relay, then I don't put them back up in the firewall when I install them. I just zip tie them down out of the way for easy change next time.

If the fuel pump primes, then check the distributor. Take the cap and shield off and see if there are any shavings or dusty residue in there. If so, then it could be keeping your sensors from firing right.

 

Oh, 28.5 MPH on your 92 is not that bad. That is about what I get... and I have over 350K on mine.

 

Had it bookmarked:

http://techauto.awardspace.com/mainrelay.html