Re: [DML] Re: HOT or COLD START PROBLEM?

[Peter Lucas <lucas@xxxxxxxx>]

Well, as I've reported before, I have confirmed the existence of a  
"warm start problem" that has nothing to do with rest pressure and is  
definitely distinct from the classic "hot start" problem. My symptoms  
were very similar to Daniel's:  starts fine when cold and when hot,  
but if you let it sit for about an hour, it is difficult to start.   
Since I have a full-time fuel pressure sensor, it is very easy to  
check rest pressure, so I know for sure that this wasn't the problem.  
Swapping the plugs does permit an easy start, but this doesn't prove  
a rest-pressure problem, just that extra enrichment helps (after all,  
there is no rest pressure present on a cold start).

What causes the Warm-Start Syndrome?  I really don't know. Obviously,  
there is a temperature window that is too high to trigger the thermo- 
time switch but at which this engine still wants extra fuel. I've  
tried lots of stuff (all of which has been repeatedly suggested in  
this and previous threads on this topic). There has been no magic  
bullet, but my impression is that lots of things have contributed to  
small, cumulative improvements. At any rate, I have not had to swap  
plugs in more than a year, although I still experience difficult  
starts from time to time.   One thing that I haven't done yet is to  
systematically clean up all the ignition 12v electrical connections  
and the resister bypass relay.  My best guess is the the problem is  
the cumulative effect of lots of small issues, but who knows?

At any rate, I am quite sure that not every temperature-related  
starting problem has to do with rest pressure.

--Pete Lucas
VIN #06703


On Feb 25, 2006, at 12:15 PM, David Teitelbaum wrote:

> You *may* have a bad thermo-time switch but you definately have a
> problem with your "Rest Pressure". That is the pressure that is held
> for a while to restart a warm engine. It is kept up by the accumulator
> but it can be lost quickly if you have a bad fuel pump check valve or
> a leaky Primary Pressure Regulator. I would go ahead and replace the
> accumulator. If you still have the problem then get a new check valve
> and replace the "O" rings in the pressure regulator. Be careful not to
> change the setting. That should fix your hot-start problem. I would
> not think the thermo-time switch is a problem but it is easy to test.
> Doing the plug-swap confirmed the problem with the rest pressure.
> Generaly if the thermo-time switch is a problem it makes the car hard
> to start when cold but I guess it can fail "on" where it would make
> the motor over-rich when starting warm-hot. Easy test. On a warm motor
> pull the plug to the cold start valve and see if there is any power
> when warm-hot and cranking.
> David Teitelbaum
> vin 10757



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