intermitent hot start problem

[Kneale Brownson]

When my '87 5ktq exhibited the same behavior, it turned out to be a crack 
in one of the oddly-shaped molded hoses (read expensive from the dealer) at 
the rear of the engine.  I surmised the rubber softened slightly with heat 
and allowed the crack to open enough to cause fuel/air mix problems.  Crack 
wasn't visible until I took the hose off.  If I remember correctly, it was 
a crack just into the hose from where the hose clamp went.


At 07:14 PM 03/11/2001 -0500, DAWSON-MD wrote:

>I have been fighting a hot start problem on with my '87 5Ktq (approaching
>200K miles) for about 6 months. It would occasionally fail to start after a
>short hot soak of 5-10 minutes such as when getting gas or stopping at a
>convenience store. If I let it cool down for about 20-30 minutes it will
>start right up as if nothing happened. This would occur about once or twice
>a month but now it happens often enough that I avoid turning it off. Last
>week I had the unpleasant experience of having to bum a ride the rest of the
>way into work from my jerk of a manager after such a failure. He happened to
>stop for breakfast at the same place and on the ride in I got a lecture on
>buying a proper new "merican" car. Needless to say it is no longer just an
>inconvenience. In the past it has always happened under one or more of the
>following conditions.
>
>1] it's dark out and I can't see much
>2] it's very cold out
>3] it's raining / snowing
>4] no one is with me to turn the key while I am under the hood
>5] no tools with me
>6] I am late for work or an appointment
>7] all of the above
>
>Two things that I have ALWAYS been able to confirm are that the fuel pump
>and relay are working and that there is spark at the coil. Sometimes it will
>start after a short wait but will stumble and miss until it "clears it's
>throat" and then it will run fine. Once I bump started it down a hill. The
>engine was turning over but it didn't hit a lick for about 4 seconds then it
>fired right up to a smooth idle. Maybe the vibration of the bump start
>jiggled a loose electrical connection or something that was mechanically
>bound up due to the hot soak. Today I was able to induce the failure in my
>driveway, WOW  light, tools and everything, this should be easy now!. A
>timing light shows that the ignition system is working fine, plenty of
>spark. Next I checked the airflow sensor disk for sticking and dirt, all was
>well. Still no start, it doesn't even hit a lick. I take a break to think
>about it and 30 minutes later it starts instantly as if nothing ever
>happened. Over the last several months I have been replaced the fuel pump,
>fuel filter and fuel injectors. Several times when parking the car I try to
>restart it and it always does; but sometimes it won't start 5 minutes
>latter. Current theory is that the idle stabilization valve sticks in a
>position causing low manifold vacuum (airflow sensor doesn't lift) or the
>freq. valve is sticking reducing fuel pressure. This "no start" only happens
>intermittently and the car runs great otherwise. Anyone ever experience a
>similar problem? Suggestions? (different than my manager's please)
>TIA
>
>Mike
>'83 UrQ
>'84 4Kq
>'87 5Ktq
>'77 Ferrari 308 GT4
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