Re: Request for Diagnostic help (sorta NC)

[Shannen Durphey <Shannen@grolen.com>]

Choke heater circuit is routed through N.O. oil pressure actuated
switch.
In some cases, checking the pin on the distributor requires removing the
distributor.  You can't always tell by grabbing the rotor and trying to
turn it. 

Ok, basics....  Make sure timing's still in spec, check and
clean/replace all plugs, make sure you have spark on all cylinders. 
Cheap spark tester can be made by opening a spark plug gap to .1".   You
can make the engine run?  Closing the choke by hand can make an engine
which is starving for fuel run better.  Doing the opposite to make the
car run indicates too rich.  Make sure the crankcase isn't full of fuel
due to bad choke.  It happens more often than you'd guess...  Look at
large diameter charcoal canister purge line for signs that the purge
valve is leaking.  Remove the purge line from the carb and look for
fuel.  This is not uncommon...
Look inside carburetor for fuel dripping into engine while the car's
running.  Dripping indicates the need for an overhaul.  

If all else fails, start throwing parts at it.  It probably won't make
the car run better, but you'll relieve some stress and you can tell the
insurance agent the damage was caused by basketball sized hail.

Brent wrote:
> 
> I'm begging for some help.  Please excuse the offtopic post.  If you
> respond, please do so offlist.
> 
> I'm working on a friends '86 Camaro, LG4, auto, CCC carb, stock.
> 
> Around thanksgiving the car severely lost power.  The next day it would not
> start.  Would crank and sounded like it was trying to run.
> 
> A tech was called, he installed a new ign module.  The car still wouldn't
> start.
> 2nd party installed a new timing chain.  The old timing chain was fine.
> Still no start.
> 
> I pulled some plugs.  They were fouled badly.  I checked the coil with DVOM.
> Coil tested bad.
> Installed plugs and coil.  Car lit right up. First try.
> Ran great.  Adjusted timing to factory spec (off 6d).  Continues to run
> good.
> I notice the choke heater not operating properly (owner is planning to fix
> it later).
> 
> One week later, car severly looses power,  the same as before.  Engine
> shaking the car.   Refuses to start next day.
> Owner cranks the car in several attemps to start the car.  No good.
> 
> I pull plug # one.  Slightly black (suspected choke heater failing), not
> wet.   I crank the car and finally after pumping the throttle many times, it
> starts.   It runs horribly and requires 1/4 throttle to maintain 1100rpms.
> We hold the choke open and the engine gains 100 rpms. Still VERY rough.
> Sounds like 3-4 cyls at the most firing.  Engine never cleans up.
> 
> I suspect ignition trouble.  So I follow Helms procedure to check the HEI.
> Coil, module, pickup all test ok.  Parts  store tests module as ok.  Scan
> tool reveals all sensors within spec.  M/C solenoid clicking happily.  With
> the 4 wire est connector disconnected it won't start.  Dissy shaft cannot be
> turned, pin not sheared.
> 
> Hair pulling out begins.
> 
> If anyone can offer a suggestion, I would greatly appreciate it.
> Some other parties want to throw parts at it  (carb, dissy)  and I just
> can't see doing that.
> 
> Regards,
> Brent
>
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