Warm Start Problem with 200 TQ (when it is very cold)

["Fred L. DeRoos" <flderoos@mmmpcc.org>]

> F.L. DeRoos wrote:

> Any ideas on a warm start problem that I'm having?  The car starts
> fine when cold, but if the ambient temperature is around 0 F or lower,
> the car is hard to restart after warming up.  It takes 1-2 minutes of
> cranking.  The check valve on the fuel pump has been changed 5-6
> times, but the problem either returns or is not really corrected. Last
> weekend I added a push button to allow me to operate the cold start
> valve manually.  When I do so, the car starts fine.  This problem has
> existed since the car was new and he dealer was unable to find it.

>>Phil Payne responded:

>>Have you got the fuse slot on top of your fuel pump relay?

Yes, but I haven't verified that it is connected internally.  My car
(early 1990) came with the code read out connectors under the dash and
without a bulb in the "check engine light" socket.  I've added the bulb
and read the codes out using the connectors and the check engine light,
but haven't tried with the fuse slot on the fuel pump relay.  I'll check
this and see if it works.  Otherwise I can do the test with the
connectors.

>>If so, recreate the failing situation, switch off the ignition, put a
>>fuse in the slot, switch the ignition back on, and wait four seconds.

>>The fuel pump will run.  Let it run for half a minute, and then try
>>starting the car.  If it's as bad as before, the problem is probably
>>sensor/electrical and I'd start with the ground wires to the manifold.

I'll try this test and see what happens. I have three brown wires
attached to the intake manifold.  I've checked them and they are clean
(not corroded) and have essentially 0 ohms resistance to other grounded
parts of the car, e.g., alternator frame, etc.

>>If it starts more easily, wait until you can repeat the test - but
>>this time pull the connector off the warm-up regulator before testing.

Do I then run the fuel pump for another 30 seconds with the connector
off the warm-up regulator before trying to start?  Or just remove the
connector from the warm-up regulator before trying to start?  I think
you mean this.  

>>If it's bad again (but was easier last time) I'd point the finger at
>>the warp-up regulator.  If it's easier (and was easier last time)
>>something, somewhere is leaking fuel pressure back into the tank. 

If I understand correctly, the first test of running the fuel pump
should represurize the fuel line and allow the car to start more easily
if fuel was draining back into the tank.  The second test of
disconnecting the power to the warm-up regulator should shunt less fuel
back to the tank resulting in higher fuel pressure to the injectors,
thus a richer mixture. How much heat does the warm-up regulator get from
the engine block?  Would a warm (hot) engine block be enough to keep the
fuel injector pressure low even without power to the warm-up regulator?

Thanks for the suggestions.  It would be nice to fix this 8-9 year
old problem.  Does the fact that it only occurs when it is 0 F or
lower point to anything?  I've considered the possibility that the
deformation of the elastomer seal in the check valve takes a set when it
is cold.  Then when the check valve closes (fuel pump off), if it
rotates slightly while closing, there will probably be a leak.  It's
hard to believe though, that I've had 5-6 bad check valves and that
others in cold parts of the world don't see this problem.  Operating the
cold start valve manually would purge the fuel line of air more quickly
(assuming that the fuel drained back to the tank) and allow the engine
to start.  The speed with which it starts after pushing the button,
however, leads me to believe that the fuel is up to the cold start valve
when the engine is first cranked. That leaves low pressure to the
injectors and makes the warm-up regulator (as you suggested) a strong
candidate.

Thanks again,

Fred L. DeRoos