I realize this question has been addressed seventy bajillion times, however I wanted to post my specific symptoms to see if I can at least narrow down the possibles. This is a '93 940 Regina system wagon (I can't imagine that matters). A few months back, on a morning after a rain and a turn to cooler weather, it began exhibiting an issue. It cranked fine, and idled fine for a bit, was even able to drive it down the driveway before it stalled. It did restart but I didn't try to go out on the road with it that day. In the following weeks, this issue has repeated, and always after a rain, although not driven in the rain, just... after a rain. Most days it will run just fine but after a rain it usually behaves this way. The other day I test drove it and it cranked and I drove several blocks before it began stumbling. I was able to get it home without dying by juicing it a little. This morning (NOT after a rain) it died shortly after cranking, then idled until put in gear, at which point it died, over and over. And after it died, it did not crank up right away. I also noticed that even in park I could get it to die by pushing on the gas pedal too fast, whereas it would run fine as long as I eased my foot down on the pedal. So I have a couple of questions: first, do these symptoms narrow down the possibilities in any way? and, there is another symptom I had noticed with this car before this issue had shown itself. One day while working on it, I thought I felt a mild shock from one of the hose clamps on the air intake. That didn't make any sense, but when I checked it with a voltage meter it definitely shows over 1 volt of current. Is this an indication of a bad ground? And if so, could it be related to this intermittent stalling issue?

 

I'd check my distributor cap/rotor and make sure no water is getting past the cap. That is pretty consistent with your description. Also very easy to check.

It won't hurt checking/cleaning all your grounds. I can't imagine why a loose ground would only cause problems in the rain but again it won't hurt to check.

 

I should have said in my original post the distributor was the first thing I checked (having had issues in the past w/ 240s).

 

Do you a CEL on? You should with the symptoms you describe, see if there are any codes in the OBD box. You may have a dodgy CPS (crankshaft position sensor). I think "after the rain" thing is incidental... Sure, check the "grounds". You may have a fuel delivery issue, may be the fuel pump acting up.

 

No CEL. I also have to say, it doesn't "feel" like any fuel-related problems I've ever had, and I've had a few.
The SRS light is on all the time.

 

Have you noticed where the water is running under the hood? You may try recreating this with a water hose. Maybe some degraded wiring under the hood.

 

Maybe. Except it's now doing it even when it hasn't rained.

 

See why the SRS is on, the OBD system should be able to tell you. Strange you have no CEL with all the running issues you are experiencing, oh well, these OBDs are not the best on these cars.

Re water, you have a rear mounted distributor I presume? Then you may have some water issues if your dist. has the plastic surround shield. Remove it! 1993 are not known for bad wiring, normally.

 

The distributor is not rear mounted on this car.

 

The front mounted dist.( a la 240) is rare on 940, I have one too with a Regina... So, the water in the dist theory is out.
I'd test the fuel pressure when these episodes occur, also make sure all your tune up items are well sorted.

 

So I rechecked the "paranormal voltage" phenomenon. I'm including a photo with arrows showing where I'm getting voltage readings. Mind you, the meter jumps around, but on these hose clamps, attached to the air intake and not touching metal anywhere, I'm getting readings from .25v to in some cases over 4v. I checked other locations under the hood and get nothing. Any ideas? This seems nuts to me, but I'm thinking it could have something to do with my intermittent issue.

 

Where do you place the other end of the probe? One on the clamp, the other? I have the same car but a '94. I will do the same test, just tell me where you place the probe.

 

I've got the meter set to 20v DC setting, putting the red lead on the hose clamp, the black one to ground, somewhere on the block. Here's the weird thing: it doesn't seem to matter if the black probe is touching anything; I still get a reading.

 

One thing that gets over looked a lot is the cps(crank position sensor). I had intermitten starting problems on my '93 940 and looked at the cps from the top looking down and it seemed fine. But when I ran my hand under the wiring to the sensor it was frayed. So I disconnected it and sure enough some of the wiring was not only exposed but it had holes in it(imagine a coax cable that has holes in it). As soon as I replaced it it worked fine and even idled better. Water being splashed against that wiring could be separating it or grounding it. That would be my guess.

 

I am no electrician but it seems to me that you have a faulty meter. A lead not touching anything should not produce a reading... may be I am missing something? I doubt that even if those mysterious readings were correct that would have anything to do with causing stalling. I'd suspect a MAFS causing your issues but you don't have one in this car, it uses the pressure sensor which rarely fails but you may want to test it:Regina Manifold Air Pressure (MAP) Sensor. The Regina fuel injection system uses air pressure and temperature in the intake system to compute the air mass moving into the engine. The MAP pressure sensor is located on the driver's strut tower support. It is connected to the intake manifold through a hose and takes a reading of intake pressure. The sensor is piezo-electric and changes a voltage input to an output signal proportional to manifold pressure. The system calibrates atmospheric pressure when the engine is started and under full load conditions. To test, turn ignition "on" and test the back of the sensor connector or the pins on the back of the ECU connector (do not disconnect with the ignition "on"):

• Connector A or pin 6 is ground
• Connector C is the constant voltage input from pin 7 on the ECU and should read 5 volts to ground
• Connector B is the variable output signal from the pressure sensor to pin 11 on the ECU. Connect a hand vacuum pump to B or 11, apply vacuum, and read the signal. Voltage should drop from 5 volts to a lower number. If it does not drop, replace the sensor.

 

As far as the mysterious readings: it only occurred to me to check because I got a mild shock from a clamp - a clamp nowhere touching metal.
Disregarding the mysterious readings doesn't change that. I checked other clamps on other parts and got no reading at all. Anyway, I wasn't necessarily thinking this had anything directly to do with causing the car to stall, but it is something I'd like to understand and solve if possible, as it means something very strange is going on and WHO KNOWS how it might be affecting things? I will test the pressure sensor as you recommend and report back. The main issue with testing in this case is the intermittent occurrence of the problem.

 

I'd share your curiosity. It's just that a clamp tightened around a rubber hose should not have current, rubber isolating electricity is a pretty major tenet of physics and engineering, etc.

 

Exactly!

 

I finally got around to replacing the crank sensor last night. It cranked right up afterwards, but this morning it won't start at all. Is there something that has to be reset when replacing the crank sensor?

 

Since you replaced the CPS, have you verified you get spark on all cylinders when cranking? Also, presume you are sure you have no water contaminated fuel
in the tank?