[DeTomaso] Why is it hard to start cars that have been sitting for months?

[Charles McCall]

Hi all,

 

Please note that this is not a problem, it is curiosity more than anything
else. 

 

Last weekend it was unseasonably warm. It had rained the entire previous
week, washing the salt away. My wife commented that we were out of sherry (I
don't drink the stuff but she likes it) so I decided to take the Pantera out
to buy her some sherry. The Spanish equivalent of two states away. It took
nearly 4 hours for me to get to the supermarket and back, mostly on deserted
backroads. Am I self-sacrificing husband or what? I don't know if she'll let
me go out by myself in the Pantera to go shopping anymore though.

 

Anyway that's not the point. The car hadn't been started for probably 4
months, literally. During that time, all the fuel evaporated from the carb
and fuel line, so it took a while for the engine to fire. The battery was
fully charged (thanks Thomas!!) so turning the engine over was no problem.
All that I see as perfectly normal and understandable. 

 

When the engine fired, I think it was running on about 2.5 cylinders for the
first minute. Then another cylinder joined the party. Probably literally two
minutes after starting the engine, another cylinder began firing. The car
rocked and shook due to the imbalance, and I was filling the garage with
unburned fuel. I pulled out of the garage and the car was probably running
on 7 cylinders. It was possibly a good 4-5 minutes before it was running on
all 8. 

 

And then all was fine. With the engine warm and all the cobwebs out the
engine ran and felt perfect. 

 

I'm just curious as to what is happening mechanically in a cold engine that
hasn't been started for many months that prevents certain cylinders from
firing until good and warm. It's an intellectual exercise more than anything
else, although I do wonder if there is something that my engine is telling
me. 

 

Is this caused by a weak spark? Plugs that don't fire when cold? There are
only three possiblities, right? Lack of air, lack of fuel, or lack of spark.
Obviously if oxygen reaches one cylinder with a common carb and manifold, it
ought to reach all of them. Same with fuel I think. That only leaves sparks.


 

Does some kind of crud form over the spark plugs if they sit for months?
Does it all burn off if so? Is my engine telling me that I need to change my
plugs? Is this temperature related or time-related - by that I mean does the
engine smooth out because the plugs have warmed up to operating temp or
because they need x minutes of firing to burn off the crud? 

 

I've got an MSD 6AL in case anyone is curious. 

 

Again, this isn't a problem, I'm just wondering what's happening inside my
engine (or any engine for that matter) when it sits for months at a time. 

 

Thanks!

 

Charles McCall

1985 DeTomaso Pantera GT5-S #9375

"Raising Pantera Awareness Across Europe"

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