Good question, and I hope someone knows for sure.
I have fought the security system in this era car (Reatta) because of the
way it sometimes refuses to let the car start. It is usually triggered by
the code key system being misread, or sometimes other cockups, but
the car will not start when tripped because the artificially generated
pulses from the computer are supressed. I cant remember now whether
these pulses are fuel injector pulses or spark pulses, because the system
is just not fresh on my mind.
My idea was to generate these pulses by a separate "black box" and
bypass control of the starter solenoid to crowbar a start condition.
Then I came to the conclusion that this was just "too much sugar for a
Maybe I will give it to Heritage for the Blind. They can drive it as well
as I can....just sit in the seat, close your eyes, turn the wheel, and make
"boodn, booden" noises, and imagine you are going somewhere.
These systems can, obviously, be a serious PITA, and there have been
times I have wished someone wanting to steal the car COULD get it
started and take it away forever.
Look forward to the answers you get.
There is no fuel delivery if the engine isn't turning and this applies
to every automobile engine since the invention of the internal combustion
In the days of carbs, manifold vacuum was required to draw fuel.
Afterwards with fuel injection, the control system operated off
crank position. No crank movement means no signal to the injectors
and thus no fuel delivery.
Yes, there would be a big difference. And I think he may possibly be
seeing some problems that I ratherly poorly described in my post above.
I'll dig back into my files and refresh my aging grey cells about how this
POS security system works.
Correct... cranking is not the issue. The question surrounds the
relationship the computer might create between spark and whether or not to
allow voltage to be applied to the fuel pump.
Normally, when you turn the key on the pump powers up and pumps pressure
into the lines, right? If you have a hosed coilpack and/or ignition module,
does the computer 'fail to tell the pump to power up' is what I'm asking.
BTW, in carbuerated engines, we often have to give the car one half pump and
then let off or three strong pumps and hold it for a second and then let off
and crank or give it one quick shot followed by a slight depression to be
made a whole depression once the thing tried to fire or, or, or any of the
crazy fun secrets cars of that vintage had for the purpose of getting fuel
to the chamber prior to having it actually run.
Won't guarantee it without seeing the shop manual for your car, but most
likely it works as in the link below.
You should be able to measure fuel pressure if the PCM hasn't failed and
if the fuel pump is good.
If you have no codes to guide you, you'll have to buy diagnostic tools
and learn dianostic techniques.
Or start thowing parts at it.
Might be better to just have a pro diagnose it.
See 3800 PCM Operation
I've had 3 different types of fuel pump failures (or near failure.)
Four different vehicles.
1. Complete failure no go twice.
The common way to diagnose with FI is make sure the pump is getting
juice, and measure fuel pressure. Simple as that.
One was a mechanical pump on a 352 and I knew what that was instantly
since it was the only thing I hadn't just replaced when rebuilding.
2. Long cranking, or no starting when pump was hot. When I had to
jump on a bus with my wife to get home so we could eat the chicken I
had just bought, I decided to take it to my mech.
Didn't kill the battery cranking it because I figured it would start
early the next morning when my wife dropped me off in her car, and it
did. It was a hot evening, but cooled at night.
He couldn't take me for a few days, but I had no further problems in
the meantime. Ran fine at 70 on the highway.
He said the pressure was so low he couldn't believe I drove it in.
(I mean he was shocked, shaking his head, said it was just putting out
3 psi, so keep that in mind.)
That was a 2.8 in my Celebrity.
3. Stalling when backing up with a low tank. That was the only
symptom, but a new fuel pump fixed it.
So there's a few fuel pump failure modes, and I'm sure there's more.
The 2 instances of ignition module/coil pack failures I've seen (both
GM 3.1's) were sudden severe misfiring and a cherry red cat.
Both cats were okay and replacing the module and packs fixed it.
But I've read of many type of module/coil pack failures including
intermittent misfiring, not starting at all, not starting for some
time, etc, etc.
None of the vehicles above was as old as yours.
Your car is 21 years old and qualifies for every component failure
known to mankind, so it's not a far stretch that 2 hit at once.
And it's quite possible that your fuel pump was so weak when they
measured the pressure they ass-sumed that was your problem.
It would have got you soon anyway.
That's how I'd look at it, though I understand how you feel,
You could ask them how they tested the pump to ease your mind.
The ECM triggers the relay independent of spark control.
It should enable the pump for 2 seconds when you turn the ignition on,
and during cranking.
There is no security system effecting fuel control on this car.
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