Engines dies when decellerating

[Devil's Slide Doug]

Idle/alternator? problem was "Engines dies when decellerating"

Yesterday I stopped at a stoplight (transmission in neutral) and instead of idling the rpms just dropped down and the engine died. All the electrics functioned still. I simply restarted the engine and drove away.
Same thing happened today. No warning at all the engine died as I came to a stop (I had already driven on the highway for about a half hour). Again it restarted and then idled normally. No check engine light or funny sounds or anything.
The only thing out of the ordinary leading up to this was a good high speed drenching of the motor (in deeper than expected puddle in a rain storm) several days ago. On that day the motor died and I assumed it was a wet dizzy but did not open it up as the truck started right back up.

 

[NorCalBorn]

Doug, I'll assume it's the truck.. Checked the vacuum lines, egr (pop the plastic cover and check for moisture) timing, idle speed and dashpot yet?

Pacifica, right, lemme know I'm semi-local if you need a hand.

 

[Devil's Slide Doug]

Yes, the mini truck. Vacuum lines appear to be all there. Timing and idle speed were checked and adjusted before my last trip to the smog shop. Dash pot is backed off all the way as to be non functional (as it has been for several years). I did not think to check the egr valve for moisture. Since posting My truck has naturally ran perfectly normal and this issue has not popped up again. My guess is it must be moisture somewhere that is hopefully all dried out.

 

[Bogo]

Check the actual vacuum pressure.

 

[WristPin]

Check the actual vacuum pressure.

thats an oxy-moron.

what our dysfunctional candidate for sanity means to say is measure how many inches of mercury your engine is pulling

if you get 19-20 inches your golden anything less than 15, you got timing issues.

but i would venture to say you may have a fuel filter issue, or a loose AFM connection, or a loose ground,

 

[Devil's Slide Doug]

Update,
I have been busy at work and not troubleshooting the truck since its been running fine. The weather has been nice.
Today I drove the truck in the rain and noticed that when warmed up and idling at 750 if I turn the lights on the rpm's drop a bit. Wipers drop the rpm's a bit more. The sure way to stall the motor is to turn on the blower for the defroster.
The blower seems to be killing the motor. During all this there is no charge light and the voltage on the factory gauge is just below 18 as it has always been since new. the rpms will drop when any electrical accessory is turned on. There seems to be no issue at higher rpm's and the truck always starts easily.
It is cold and rainy and dark so I am holding off on troubleshooting at the moment but I am open to more ideas.
I am starting think I have an alternator, battery or grounding issue.
Any other ideas?

 

[raydouble]

During all this there is no charge light and the voltage on the factory gauge is just below 18 as it has always been since new.

Just below 18 volts? That isn't right....

 

[Devil's Slide Doug]

Were talking factory dash gauge with no real scale. Where it has always been since brand new. I still have not ruled out that it is a vacuum line or egr issue and that the load of an healthy alternator is enough to bog down the idling motor. Does that make sense? Although i would expect it to run poorly or miss if that where the case.

 

[raydouble]

Were talking factory dash gauge with no real scale. Where it has always been since brand new. I still have not ruled out that it is a vacuum line or egr issue and that the load of an healthy alternator is enough to bog down the idling motor. Does that make sense? Although i would expect it to run poorly or miss if that where the case.

You've got to get a real multimeter on the battery and check voltage + charging voltage + voltage with the blower motor on.

 

[Devil's Slide Doug]

I just tinkered with the truck a bit and confirmed that the voltages are all reasonable at the battery (according to my voltmeter 12.68v turned off and 14.5v) at any rpm with or without accessories on but with my head in the engine compartment did confirm a squeal from my alternator whenever electrical accessories are turned on. Might be some bad bearings? I did not think an alternator would bog down an idling motor. Just for kicks I did also confirm that the egr system is working (assuming I actually applied vacuum to the proper hoses and such. Checked the modulater, vsv and when vacuum was applied to the hose that goes to the top of the actual egr valve it kills the motor when idling as it should). It is looking like a bad alternator. It has been dunked in water on more than one occasion.I guess they dont like that. This one only has 180,000 original miles on it.

 

[NorCalBorn]

*I forgot to mention, let me know if you decide to take up my offer, I can bring my Fluke with me. A good voltage won't necessarily show/reflect a dead cell or poor amperage output or excessive draw or a partial dead short happening, a Fluke set to record/map will show it though.

Let me know what the alt bearings ended up feeling like.