Carrera stumbles, dies in rain; then fine

[techweenie]

Odd happening last night In the rain. Idle was a bit rough, but it ran great until coming back late. The engine stumbled a bit in the freeway, so I exited. At the first stop, it was idling rough and died when the light turned green, but immediately restarted. I drove 1/2 mile to the nearest gas station (it was showing 1/8 tank) and added 4 gallons of expensive Bel Air gas. Wiggled all the spark plug wires & coil wire, but nothing was loose. Restarted the car and it drove perfectly. Now I'm a bit wary...

Ideas of things to check? Car is 1985 Carrera, 232K miles

[86 911 Targa]

The rotor & distributor cap.

[techweenie]

For arcing? Or...?

[ossiblue]

Just a guess but possibly you had less gas than indicated and with the extreme humidity lately there was enough water condensed in the tank to make it to the fuel intake. Adding fresh gas agitated the water and displaced it enough to allow free flow of gas. Anyway, it's a thought...

[Joe Bob]

Moisture inside the cap. Heavy grease around the edge of the cap helps.

Other suggestion is your DME under the seat is in a puddle. CA had some extreme rain I've heard.....

[kidrock]

+1, inside dizzy cap. Spray with WD-40 and wipe inside of cap. Check rotor and clean if necessary.

[techweenie]

I suspected gas at first, but today on a (dry) drive it felt strong, but at idle, I noticed a vibration in the outside mirror, which it has never had before. So I'll check inside the distributor cap and see if that helps. I may also have a failing plug wire or two... Thanks, guys!

[KTL]

A ffiend has this problem with his '87. Always puts a cover over his grill screen on aftermarket fiberglass whaletail because water gets on the dist cap.

However don't rule out the DME reference sensors too. If the wire sheathing is old & cracked, you casn see a similar intermittant stumble

[dshepp806]

Many things at play.....

Doyle

[jorian]

Agree on moisture inside the cap. This happens when our lot attendant at the office washes the cars and gets a little carried away during the rinse.

[techweenie]

Circumstances suggest moisture is culprit #1, but it shouldn't have been idling rough today when there was no rain. I had the car outside in the sun for over 2 hours before driving, and put 15 or so freeway miles and 8-9 street miles on it before seeing the mirror vibration. OTOH, by then I'd run through a couple of the 4 gallons I added last night... maybe time to drain the tank. Here in So Cal we don't think to avoid leaving the tank 3/4 empty like one would in an area with more frequent high humidity...

[stlrj]

Quite common to have corrosion in your Beru connectors causing a miss when wet that eventually leads to a failed spark plug(s) which will not come back to life.

[hexranr7]

Originally Posted by ossiblue

Just a guess but possibly you had less gas than indicated and with the extreme humidity lately there was enough water condensed in the tank to make it to the fuel intake. Adding fresh gas agitated the water and displaced it enough to allow free flow of gas. Anyway, it's a thought...

yeah~ I have that thought too, more like gas problem.

[stlrj]

If it were a gas problem, everyone would be experiencing the same problem in your area whenever it rains and we would be hearing about it on the 6 o'clock news. Seems like a long shot.

My vote is for a more local problem and would put my energy into wet ignition issues.

[Targa Me]

check out a thread called "Air Cooled Engine with Water Problems", its a few pages down. (sorry i don't know how to link it).
I have an 84 Carrera basically doing the same thing your car is doing.

[dshepp806]

How's about a little service history?

last changeout of dist cap, rotor, plug and coil wires, ICV cleaning, idle mix setting?

Doyle