1996 Buick Regal, 3.8L NA, ~ 85K Miles
Starts and runs fine until fully warm (approx. 1/4
temp. sweep range), then dies and won't restart
despite cranking fast (normal), having spark (at
coil pack secondaries) and fuel sprays at rail
bleeder shrader valve when depressed. It will
run while using starting fluid, but again stops
when that spray is discontinued. It starts and
runs fine again when cold. This scenario is fully
repeatable everytime it reaches full temp and
restarts everytime it's cold. The "service engine"
light does not come on (although the bulb works
and illuminates normally during the key on test)
and an Auto Zone scan doesn't show any stored
fault codes. I've not yet checked the fuel pump
or its relay but expect those may not be the issue,
although I realize the pressure COULD be too
low or the relay might be losing its signal/power
supply. Other guesses are that the injectors aren't
receiving a signal to open or spark is occurring
at the wrong time (unlikely as it neither backfires
nor cranks too fast or too slow).
Any advice, thoughts, opinions or experience
with this type of problem that you may have to
share would be greatly appreciated.
Thanx for your time.
Could be. A bad ECM on mine killed the engine occasionally,
but it restarted every time but once. That time it started ten
No problems in the winter, but first really warm day of the spring the
ECM died completely.
Same car would fail to restart when it had been run awhile, until the
fuel pump cooled off. Glitched when accelerating too.
Mechanic was shocked I had driven it in, as the fuel pressure was so
low. Fuel pump fixed that.
'88 Celebrity 2.8. Probably not much different than the Buick.
The pump is the easy one to eliminate with a gage.
Good input, thanx. I'm a former mechanic (haven't wrenched
for a living since '79) and still have most all of my hand tools,
but no longer own or have easy access to accoutrements such
as gauges, carbon pile rheostats, exhaust gas analysers ... ;^(
although I still have an old TV repairman's Sencor oscilloscope
in storage that I'm considering breaking out to check the injector
I would not suspect an ECM with the described symptoms. The ECM is not
really running much hotter with the engine temp as described by the OP, so I
would not suspect it. I'd look more at the fuel delivery system.
Sounds like a bad control module, or ECM
I haven't had an opportunity to return to this issue yet,
but I also think that's a possibility. I was surprised by
the starting fluid results as my gut feeling had been that
the problem was related to spark (thinking that a failing
transistor integrated in the Hall effect crank position
sensor was failing, that or a bad ICM), but testing
revealed that that was obviously not the case.
Btw, should it turn out that the ECM is the cause of
the malady, might anyone be aware of a method by
which its replacement can be flashed (such as with
my own laptop) without having to go the route of
providing the aftermarket supplier a 50% surcharge
for that service?
Again, my thanx for your feedback/input.
I think this is your first clue..If it will run when being
forcefed starter fluid, then you likely have a fuel
I have seen GM ECM's do this, but it may well
be something else.
Sounds like you can eliminate ignition, compression,
Bad fuel pump OR pressure regulator on the fuel rail. More likely the
pressure regulator. Use a pressure test gauge, see what you have key ON
engine off, then start the engine and see where the pressure sets. Now
shut off the key and see if the pressure stays.
If the key on engine off pressure is OK (52-59PSI) it probably isn't the
pump, but run a capacity test just to be sure.
Yes, that method is the correct, standard procedure
for testing both pressure and volume of the fuel
delivery system, even in a carbureted application.
However I think that in this case, evidenced by the
sudden and repeatable onset, the issue might also be
related to going from the open to a closed loop
condition, seems like almost too much of a coincidence
otherwise. But given Vic's knowledgeable experience
and your sage advice (replete with specific dimensions),
the possibility of a low pressure condition really does
need to be eliminated as a cause of the fault as well.
Thanx for your response.
See it a lot where the regulator diaphragm splits and causes a problem.
One other small test would be to pull the vacuum line off the PR and see
if you find liquid fuel or a strong odor of fuel. You shouldn't find
either but a blown PR will sometimes show up that way.
But given Vic's knowledgeable experience
Diagnostic... Take a bottle of cool water (a sports bottle, Poland
Springs, or similar).
Get it hot, so it dies. Spray the water on various underhood items,
one at a time. If the ECM is underhood spray it too. Spray connectors!
Spray wiring harnesses!
If the ECM is underdash, get a spray cooler can at Radio Shack (used
to cooler electronic circuits to find temperature related faults) and
spray the ECM and try again.
One fo these two will find the heat related component.
Try removing the fuel filter[s]. If the engine runs ok hot then you have
found the problem. Replace the filters and your all set. My 81 Malibu had
this exact same problem. A 96 needs to have the filters replaced anyway.
Thanx for your suggestion but given the symptoms and
history, I find a clogged filter, fuel tank sediment, pickup
tube or line restriction ... issues considerably less likely
than other aforementioned causes, plus the filter was
already replaced about 10K miles ago.
Chilling a suspect circuit board or device is an old electronics
repairman's trick to diagnose an overheat related issue (I last
utilized the method and discovered a faulty vertical deflection
IC in a Sony TV). Freon, or a dielectric like Fluorinert is
commonly used. But to employ a dipole like water and willy-
nilly soak energized underhood electrics sounds (to me) like
a perfectly AWFUL recommendation (no offense intended).
I do however appreciate your input and your latter efficacious
suggestion, my thanx for your reply as well.
If you were not aware that *all* underhood components are water
resistant, you should be. I thought you were reasonably compentent so
I made the suggestion. I appologize for doing so.
You should take the vehicle to a qualified mechanic and have it fixed,
that is the only solution for your problems. Good luck.
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