Engine coughing and losing power after driving in heavy rain

[beetleman217]

Camping in our 1977 Westy (stock 2L fuel injection) was fine until we drove through a thunderstorm with torrential rain. The bus ran fine in the rain, but after an hour's stop for lunch, as soon as we started driving again it started to sputter and lose power. Upon inspection there was absolutely no water in the engine bay. Everything looked normal.

We had it towed to a garage. The next morning it started fine and drove perfectly! So whatever got wet simply dried up overnight.

Now I'm trying to figure out what got wet, so maybe I can shroud it somehow to prevent this from happening again. The fuel pump and filter are the only components that sit outside the engine bay, but they're tucked neatly and the fuel pump connectors are insulated.

Could this have been water getting inside the fuel tank (through the gas cap)? Would that have resolved overnight?

Thoughts and ideas would be greatly appreciated.

_________________
If all else fails, stop using all else

1977 Westfalia
1961 Beetle

[Bnanwel]

Maybe condensation in the distributor cap? Water in the fuel would not have resolved itself.
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‘72 Karmann Ghia Conv.
‘73 Karmann Ghia Coupe
‘74 Karmann Ghia Coupe
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‘72 Deluxe

[beetleman217]

[KTPhil]

Not sealed at all. Good enough to keep too much cooling air from leaking but nothing that will stop moisture in the air from migrating from wet to dry. This is in the bay and under the cap, which is also not sealed.

I would suspect old SP wires or connectors that are arcing. Then I'd swap distributor cap and rotor with the spares you should be carrying anyway.
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Current Fleet:
- '71 Fastback
- '69 Westfalia
Retired:
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- '65 Beetle (x2)
- '65 Bus
- '71 Squareback

[beetleman217]

[Abscate]

Wiping it out with a dry paper towel will usually fix it. A trace of moisture will rob the high voltage, low current discharge and stop your Bus , cold.
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[vwmaniaman]

Spray inside the cap with some WD40 and wipe it out. Water Displacement 40. Be sure to wipe it after spraying because it is flammable.
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65 Beetle
75 Westy "Pumpkin Van"
86 Westy "Brown Betty"
87 Cabrio

[aeromech]

Electronic points solved the problem for me.
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[mikedjames]

I once had water end up over the cap of the distributor and even managed to get into the HT sockets on top.. We were driving for about 20 minutes past a French town that was having a medieval fair .. but it was raining so hard the roads were like streams and rivers. So we decided to give it a miss.
We stopped in a car park, in a "creative" space bumped up on a kerb where we were at least not blocking the roadway.. This meant the left hand side of the bus was higher and so the rain poured in.

It would not start immediately but the sun came out, we went to a nearby supermarket and did some shoppjng. And after that we continued our journey as it started once it dried out by itself.
_________________
Ancient vehicles and vessels

1974 VW T2 : Devon Eurovette camper with 1641 DP T1 engine, Progressive carb, full flow oil cooler, EDIS crank timed ignition.
Engine 1: 40k miles (rocker shaft clip fell off), Engine 2: 30k miles (rebuild, dropped valve). Engine 3: a JK Preservation Parts "new" engine, aluminium case: 26k miles: new top end.
Gearbox rebuild 2021 by Bears.

1979 Westerly GK24 24 foot racer/cruiser yacht Forethought of Gosport.
1973 wooden Pacer sailing dinghy

[SGKent]

ignition wires grounding out is a possibility. Next time you have 10 minutes in the eve, with the bus running at idle, being extra careful of the moving fan belt in the dark - long hair, long sleeves etc., use a mist bottle to mist the ignition wires. If that is it, the engine should start acting up, and you might see a halo or sparks between wires or to ground. Common issue when the wire jacket begins to fail. If so it will eventually get to the point that fog or a day with high humidity will cause it.
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[wagen19]

[my59]

Years back i sailed my dad's Chevy wagon thru a super deep puddle and the car ran like crap after. Turned out the distributor cap cracked.
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my59: Well son, my grandfather died before I got to drive it, so does that answer your question?
our79: sunroof bus w/camper interior and 2.0 FI
Other:'12 Jetta, '77 Benz 300D, and a 74 MG Midget.

[Xevin]

[wagen19]

Eventually, if the engine sheets are not complete, has holes, or the seal around is bad, from the bottom front side to trans, there can water from the street go inside engine compartment and into air box, air filter element (paper).
(rusted battery floor, holes there?)

[lil-jinx]

any air leaking around the seal would be minor compared to the air being drawn in thru the vents,thousands of liters per minute.
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https://www.thesamba.com/vw/forum/viewtopic.php?t=620186
https://www.thesamba.com/vw/forum/viewtopic.php?t=668799
1974 Bay Westfalia. she likes to be called Ethel.
1968 Dune Buggy sold dec 2024

1974 parts bus
A smart man learns from his mistakes,a very smart man learns from other's mistakes.

[lil-jinx]

friend of mine once had a k car ,it was running rough ,he blamed it on damp ignition wires, and decided to use wd40 to dry the wires ,with the engine running,it was a wonderful fire.
_________________
https://www.thesamba.com/vw/forum/viewtopic.php?t=620186
https://www.thesamba.com/vw/forum/viewtopic.php?t=668799
1974 Bay Westfalia. she likes to be called Ethel.
1968 Dune Buggy sold dec 2024

1974 parts bus
A smart man learns from his mistakes,a very smart man learns from other's mistakes.

[mikedjames]

I did have another water related issue where condensation occurred almost immediately after hitting a section of flooded road about 6 inches deep water for 50 feet of road under a railway bridge.. . The steam around the engine got into the home made ECU and for about 30 seconds after the puddle the ECU shut down and the EDIS-4 went into limp mode (it drops to 10 degrees timing advance) . Eventually the ECU rebooted successfully and the engine picked up by itself. Some silicone round the die cast box lid to create a seal and the problem has not reappeared.

There were definite signs of light corrosion inside the ECU box.

Next time the RusEFI ECU is going in a sealed box.
_________________
Ancient vehicles and vessels

1974 VW T2 : Devon Eurovette camper with 1641 DP T1 engine, Progressive carb, full flow oil cooler, EDIS crank timed ignition.
Engine 1: 40k miles (rocker shaft clip fell off), Engine 2: 30k miles (rebuild, dropped valve). Engine 3: a JK Preservation Parts "new" engine, aluminium case: 26k miles: new top end.
Gearbox rebuild 2021 by Bears.

1979 Westerly GK24 24 foot racer/cruiser yacht Forethought of Gosport.
1973 wooden Pacer sailing dinghy

[orwell84]

I think any kind of extreme condition like torrential rains, extreme heat, extended heat soak and vibration has the potential to cull the sick or weak components in the electrical system. Likewise for rubber vacuum hose boots or connectors. Sort of the same way the first cold snap kills a car battery. You realize that battery has been there longer than you thought.

I think the best way to prevent these kinds of breakdowns is to go through all those things thoroughly during tune ups. Electrical connections get loose or oxidize. The cap, wires or coil I thought I replaced a few years ago turns out to be 10 years old. The long periods of time my bus doesn’t get used put me out of the loop.

[beetleman217]

Thank you all for the input. I see the wisdom of the crowd points toward condensation interfering with electrics. It sucks that the otherwise perfectly running-like-a-german-sewing-machine bus can't handle a little rain
_________________
If all else fails, stop using all else

1977 Westfalia
1961 Beetle

[wagen19]