[imitchellg5]

My not so trusty Volvo 850 Turbo has a new issue. Whenever I go to start it, it fires up, runs very roughly then dies. I can keep it running if it is up near redline, but only for a few seconds, then it dies anyway. I think it may be an ECU issue. We also smelled gas a few days ago inside it, but now the gas smell is gone. It has 165k miles and is a '95. Is this an ECU issue? The fuel pump is working, you can hear it running and you can hear fuel moving.

[Spliffdaddy]

The gas smell is the key to the problem.

The fuel injection system requires a high pressure in the fuel rail (the pipes atop the injectors). That pressure is monitored and maintained by sensors. Apparently there is a leak or obstruction somewhere in the fuel supply or return lines. Check the filters. There are at least 2 of them.

A faulty ECU would almost certainly result in a warning light or error. The ECU runs a self-test at startup.

Other possibilities include:

Evaporative emissions canister or vent lines.

Bad MAP (manifold absolute pressure) sensor. This is mounted near the throttle body or somewhere on the intake manifold. This is what meters fuel flow to the injectors - based on the vacuum in the intake manifold. You open the throttle and the pressure increases (well, the vacuum drops). Also, the throttle position is monitored by a sensor - but that is for refinement of fuel/air mixture, and wouldn't result in the engine not starting.

Basically there are 3 required parameters for fuel injection to function:

Manifold Absolute Pressure

Fuel pressure at the injection rail.

Coolant temperature sensor.

Anything else is there for refinement - things like oxygen sensors and throttle position sensors.

[ebuddy]

Damn Spliff. I'm thinking of getting a Saab 9-3. (maybe 2003-4) Good idea? Bad idea?

Tech help if it turns out to be a bad idea?

[Goldfinger]

tdc sensor, flywheel sensor ?

Be sure to check all sensors and wireing. A mallfunctioning sensor can be the cause of all sorts of inexplicable things.

Go to a volvo dealer and let them hook the car up to their computer.

[vmarks]

ebuddy,

Please avoid the Saab, unless you want to groom a post count higher than all of macnn combined on a saab forum.

iMitchellg5,

Go to an autozone and let them scan it. They'll do it for free, because they figure they're liable to get the parts purchase.

It could also be the idle air control. This is a stepper motor on the throttle body that revs the idle up on cold starts, and adjusts the mixture by computer until about 2.5k rpm. It would explain the dying out if it isn't kicking in, and explain the gas smell. Get someone to turn the key from off to run (but not start) and see if you with your head under the hood can hear the stepper motor run for a second.

[imitchellg5]

Thanks for the suggestions. I think I'll take it to the dealer on Monday and see what they say. I'm praying that it will be unusually cheap. I also did order some new fuel filters... they haven't been replaced since 75k miles.

[G4ME]

get a 740

or even better yet get a 760

[Sbtrfuge]

Try removing your gas cap, then screwing it back on, just not tightly. Sometimes this helps with cars that like to die.

[imitchellg5]

Sbtrfuge: I have to do this already for another reason.
G4ME: I'm done with Volvo.

I put new fuel filters in today. The problem still occurs, but about every other time I try to start it, it will start. Weird.

[Rumor]

Did you try jacking up the car, removing the wheels and replacing the car?

[Sbtrfuge]

Wait... it won't start half the time? That sounds like an ignition problem. If it started everytime and died, then I'd say it be more likely to be fuel related.

[imitchellg5]

Originally Posted by Sbtrfuge 

Wait... it won't start half the time? That sounds like an ignition problem. If it started everytime and died, then I'd say it be more likely to be fuel related.

It still starts everytime but now it dies only like half the time. It will die, but I can go back to it in a hour and it will start.

[Sbtrfuge]

oh... if it starts everytime, THEN dies, then it sounds like a fuel problem. I'd get the ECU code sniffed to get mroe clues.

[Sbtrfuge]

PS: Did you know the nissan pathfinder now has independant front suspension?

VIDEO: why we love independent suspension (NSFW) - Autoblog

[Rumor]

Originally Posted by Sbtrfuge 

PS: Did you know the nissan pathfinder now has independant front suspension?

VIDEO: why we love independent suspension (NSFW) - Autoblog

*bzzt*

Paging Doofy to lounge.

[OldMacdonald]

Even though this thread was from a year ago I still figured my success was worth posting. My 95 850 Turbo had this same issue pop up, when you'd try to start it the only way it would actually run was if you kept your foot on the pedal and kept the RPM's up. Foot off the pedal, engine dies...

So I read the posts, and thought the gas cap was an easy thing to try. Yada yada yada, the crazy car, after 3-4 attempts, starts up, idles fine, runs fine. All I did was take the cap off and put it back on. I did, however, notice a strong smell of gas and maybe a slight release of pressure. Hope this helps someone...

[imitchellg5]

Ha ha, my 850 had the exact same issue, except I had to replace the fuel filters as suggested which worked. I also have the same annoying gas smell, even after replacing the cap. Luckily now I have a Honda Accord, which is a much better car than the Volvo was.

[olePigeon]

Change your blinker fluid.