Request for Diagnostic help (sorta NC)

[Programmer]

Do all of us work this late <g>...I just took a break from building a
4L60 with a stage 2...
Lyndon.
----- Original Message -----
From: Shannen Durphey <Shannen at grolen.com>
To: <gmecm at diy-efi.org>
Sent: Saturday, December 16, 2000 12:04 AM
Subject: Re: Request for Diagnostic help (sorta NC)


> 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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