[Shop-talk] Tricky problem with a GMC 3500

[eric at megageek.com]

1998 GMC 3500 mason dump.  LOW miles ( 87K)  Gas engine

When it runs, it is flawless.  Great idle, lots of power, no issues.  Kept 
in heated garage.  Always on a battery tender.

About 6 months ago (maybe longer as this truck is rarely used.)  when I 
would first start it, it would idle way too low and stall.  I few minutes 
of warm-up, and it was fine.

Then, this past month, I had to move it to one of my out buildings for 
about 3 weeks.  The building has lots of moisture (it will NOT stop 
raining and now snowing here.)

I went to start it up and it wouldn't start.  Engine turned over fine, 
sounded normal, but it wouldn't start.  After I tried a  few times, the 
engine would 'diesel' when I stopped cranking. 

I tried some starter fluid and it didn't change anything (so I thought no 
spark.)  Battery was on a 'boost starter' plugged in the wall.  Gas smell 
coming out of tailpipe.

Checked spark, all good.  Under the hood seemed dry (there was no 
condensation or anything) but the building had a wet floor.

After some wrangling with a tractor, fork-lift, and a few new vocabulary 
words,  I got it onto the main garage where I let it sit over night with 
the hood up.

So I tried it today and it started right up.  So this is clearly an issue 
with the moisture.  My question is, where do I start to troubleshoot?  I 
can't predict it being moist in the other garage (and when it's there, 
it's away from all my tools etc.)

ODBC tool has no codes.

Any ideas on how to fix this?  I'd hate to be stuck on the side of the 
road because of rain or something. 

Thanks!


Sent from my Commodore 64 on a 2400 Baud Modem.
Tech Viper
"Be as beneficent as the sun or the sea, but if your rights as a rational 
being are trenched on, die on the first inch of your territory." Ralph 
Waldo Emerson 
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