4kq hard starting-stumbling

[Chris Hall]

I notice you said you checked the -voltage- to the cold start valve
when starting... did you pull the CSV out and make sure that it's
actually spraying when it gets that voltage?

Maybe even though with the "alternate" fuel pump relay (careful, you
can burn wires up by sticking other
non-fuel-pump-but-it-fits-the-socket relays in there) and the act of
manually letting the fuel pump run and waiting 30 seconds for it to
prime... maybe your fuel system isn't holding pressure after you shut
the car off and even that 30 seconds isn't enough to get it back where
it should be?


My 83 CGT had a weird problem once where it randomly wouldn't start
cold, and that turned out to be the fact that it needed a new cap,
rotor and wires.  Don't know what the "cold" part had to do with
anything but it always seemed to happen that way.






On 6/22/05, William Perron <w_perron at yahoo.com> wrote:
> I've been having a problem w/ my '85 4kq lately that I
> can't seem to figure out.
> 
> Problem:  Hard starting when "cold"-- cold varying
> from 50F to 95F.  Car will sometimes catch when key is
> first turned, but then stalls.  After a few attempts
> the car will eventually start, but will have trouble
> idling for about 30 seconds- usually need to keep the
> revs above 1500RPM during this time - then the idle
> evens out and I can drive away.  Once car is warm, I
> can turn off and restart easily.  AFter it sits for a
> few hours, the hard starting begins again.
> 
> Diagnostics/Changes so far:
> -Checked Idle switch- it is working properly
> -Swapped ECU temp sensor with known good--no change
> -Cleaned all grounds, connections including intake
> manifold grounds for ECU
> -Swapped in known good plugs/wires distributor cap -
> no change
> -Swapped large intake manifold boot - no change
> -Attached hose clamps to all ISV hoses - no change
> -Swapped ISVs - no change
> -Checked all hoses for vacuum leaks - nothing found
> -Re-did all small vacuum hoses in engine compartment
> w/ new ones- no change
> - Installed new injector seals - no change
> -Centered air plate in fuel dist. - no change
> -Checked that Cold start valve is receiving voltage
> when cranking - it does receive voltage
> -Checked after start enrichment function--ECU does
> enrich mixture after starting
> -adjusted idle speed (w/ duty cycle meter), mixture
> and timing- no change
> - installed known good fuel pump relay no change
> -installed a normal relay so fuel pump runs whenever
> ignition is on--waited at least 30 sec to "prime
> system" ---no change
> 
> I'm really not sure what else to check at this point.
> ONe interesting thing I noticed is that the car seems
> to start pretty well if I leave the ISV unplugged??  I
> though the ISV might be a problem so I swapped in a
> differnt one--no change...
> 
> Any thoughts or comments appreciated
> 
> 
> -Bill
> Burlington CT
> '85 4kq
> 
> 
> 
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-- 
Chris Hall
badcomrade at gmail.com
"making girls cry since 1974"