Hot start problem 88 5kt automatic

[Kneale Brownson]

Does the cooling fan work?  On my '87 5ktq, there is an expensive little
hose with multiple taps near the back of the engine buried behind/beneath
some other stuff, that had a split in it that influenced hot starts.


At 07:52 PM 2/2/2006 -0500, Doyt W. Echelberger wrote:
>Friend's 1988 5000 turbo (fwd automatic) has developed a tendency to not 
>restart after being shut down hot. In desperation he asked for suggestions 
>yesterday.
>
>He drives for 30 minutes, parks in driveway, turns off engine, trys restart 
>and all it does is crank. Won't catch.
>
>MUST cool down before it will restart when this happens.....20-30 minutes. 
>And it doesn't happen all the time. No apparent pattern.
>
>Runs_ great _when started cold and stays that way as long as it is driven 
>without being turned off.....sometimes. He already replaced the oxygen 
>sensor, the plugs, the wires, the cap and rotor.
>
>Good-running spare parts type 44 of same year is sitting there waiting to 
>swap anything and everything to see what will make the problem go away.
>
>Here is what I found in the archives:
>
>This problem is rampant among UrQ's and 5000 models. Apparently is a 
>vapor-lock thing. It is the reason Audi put the jury-rig blower in there to 
>cool down the injectors and reduce under-hood temps.  Also one of the 
>reasons for coming out with the next generation of inline 5's.
>
>This vapor-lock explanation makes sense to me because we have been having 
>unusually warm winter weather (50 degrees F) here in Ohio, and the gas 
>station fuel mix is still being supplied to our area is set for normal
winters.
>
>Also could be aging of a relay that controls the fuel pump or the one that 
>causes hot-start pulsing of the cold-start valve. Or maybe a poor ground 
>for any of those relays. Or maybe a temperature sensor is telling the ECU 
>that the engine is cold. and needs the cold-start valve open, and the 
>mixture is so rich it won't run. Or maybe the RPM sensor resistance is out 
>of its range and needs replacing.
>
>Anyhow, before I get back to my friend, are there any other ideas?
>
>Doyt Echelberger
>87 5ktq that runs just fine (!) (today)
>
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