Volvo 740 GLE starts then stalls after 30 seconds

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

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

Have you tried Dry Gas? I would add two cans.

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

T> > Help !! I have a 740 GLE 2.3. I have replaced the intank and undercar

Mike,

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

Thanks John

Michael Pardee 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