Help !! I have a 740 GLE 2.3. I have replaced the intank and undercar
fuel pumps and filters. The car starts up normally then quits after 30
seconds or so. It started happening as the weather started cooling
down. Problem started at about 45 F. The car also has a new Air Mass
Unit and the fuel injectors have been replaced.

Any help welcomed !!

johnzab (AT) w1jpz (DOT) net wrote:
Need more info

Does it restart straight away, or will it not run atall then?
Does it go for 30s each time.

Have you tried holding the throttle open or reving it when you are
expecting it to fail.

Can you not drive the car and get it warmed up?

As an initial guess the fuel pressure regulator could be faulty and may
be allowing too much fuel to return to the tank.

--
Tony

<johnzab (AT) w1jpz (DOT) net> wrote

A good cleanup of the throttle body should help. The 740s get a lot of
vaporized glop from the crankcase that loves to collect in the throttle
body. Especially ensure the idle passage at the bottom of the body gets
cleaned out. At the same time, the idle air control valve under the throttle
body should be cleaned to keep it free-moving.

Mike

johnzab (AT) w1jpz (DOT) net wrote:

Have you tried Dry Gas? I would add two cans.
--
Cheers, Steve Henning in Reading, PA, USA
Owned '67,'68,'71,'74,'79,'81,'87,'93,'95 & '01 Volvos.
The '67,'74,'79,'87,'95 and '01 through European Delivery.
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Tony,

It will restart within a few seconds and run for another 30 seconds
give or take.

Yes, tried holding it open and pumping the throttle.

Wont run long enough to move it. Does run a bit longer when in gear
though, maybe close to a minute before stalling.

I have not changed the pressure regulator.

Thanks

John


Tony wrote:

Mike,

I have cleaned the throttle body, but not the air bypass valve. I will
give it a try.

Thanks
John

Michael Pardee wrote:

johnzab (AT) w1jpz (DOT) net wrote:
Its not obvously the pressure reg, but its the only thing I could think
of that might 'run out' a bit like a carb car running until the fuel in
the carb ran out if there was no fuel supply. Possibly its suddenly
releasing pressure.

You have already eliminated fuel system blockages in the main areas,
could there be something in a pipe?

It must be something faily blatant that is causing total shut down, I
guess the questions are:

Is the Engine Mgt shutting it down due to an out of spec sensor (eg
crank sensor)?

Is a key running system diing, ie fuel or spark due to.. eg an
electrical fault heating up for some reason?

Restarting straight away would say to me its mechanical rather than
electrical and so eliminate spark problems.

Running longer when in gear is a clue, but I don't know why. I assume
you mean automatic drive 'in gear'. This would mean there is some load
on the engine, possibly drawing more fuel and keeping the pressure
regulator away from its sudden release point for longer. However it
seems a highly unlikely failure mechanism to be so time constant. Maybe
pressure builds up because it is sticky and then suddenly releases
totally because the spring is broken.

A mechanic should be able to test the fuel pressure, but its probably
cheaper to eliminate the regulator by replacement.

Perhaps you could monitor the tank return feed, it could be dry then
suddenly gush just before it stalls as it losses pressure. I don't know
what would happen if the return feed was blocked, but if you could try
that briefly it might run on.

--
Tony