Sorry, my car is an 08 AMV8 coupe, and it did it again, yesterday! I filled up the tank and there it is... The car dies at turns, stops, or at any rapid move you make with the car as the fuel moves from one side to the other in the fuel tank .!!! The frequency of the problem starts to diminish as the car consumes the gas off the tank. At half a tank, it doesn't happen anymore.... AMFixer thank you for your help, but please help me understand, what does the purge hose has to do with the fuel not reaching the engine at times, it sounds more like a fuel pump issue. Pardon me my ignorance..

 

It's not a matter of fuel getting to the engine, it a matter of to MUCH fuel getting to the engine. Basically what is happening is the tank is purging vapors, but because the hose is broken/torn/fallen off, it is purging fuel. So there is un-metered fuel getting to the engine, the ecu is seeing and trying to correct for it. Thats why you get the stumble. The reason it does it when full, is that purge line sits at he top of the tank. So when the fuel moves in the tank it goes in that purge line. Which means when the fuel level drops it can not suck in any fuel.

 

Thank you AMFixer. I went to my AM dealer today and the rep. told me that the problem is actually a diaphram inside the purge valve that breaks and leaks fuel through the hose, making the tank unable to mantain constant pressure. Do this sounds right to you? Or they are just BS..ing me in order to charge me for a bigger job??

I don't trust dealers... you go for a simple hose, you go out with a rebuilt engine!

 

The line im talking about goes through at puge valve its the same system. But I have never seen the purge valve break like that. Not to say it can't happen. Hard to say without really seeing it.

 

Sorry to revive this thread. But, how do you get to the purge hose or valve that everybody says, sits on top of the fuel tank??? Do you need to take a rear wheel out, panels.. etc? How much disassembling needs to be done to get to the valve/hose??

 

Depends on what car you have. DB9 volante, V8 Roadster, V8 Coupe are fairly easy to get at. DB9 Coupe not worth the hassle of a DIY.

 

I have a V8 Coupe Vantage. Thanks AMFixer!

 

Me too. 2007 Vantage coupe. How difficult it's the job?

 

It is a fairly easy job. I would charge about 2 hours for the repair plus parts in the dealer. I don't fell comfortable giving the process to replace it, as you are in a fuel cell. I have seen other tech's blow themself's up, by not following proper repair procedures.

 

BOOOOM!

I just wanted to know where to access the purge hose, so I can tell my mechanic before he goes on a hunting expedition and starts taking things off that are not needed... I am not taking it to the dealer, if you say it is easy. My mechanic is pretty good. He used to work for MB.

 

The access plate in under the carpet in the rear hatch. Cant miss it, its a giant circle plate.

 

my car stalled out this morning. half-tank of Exxon gas, coasting in neutral up to a red light. died at about 20 mph or so.

i've been avoiding Shell since people started saying it causes problems in certain cars. but mine still died with using nothing but Exxon for the last several tanks.

 

Thanks AMFixer for all the info!

telum01:
It is not the brand of gas. It is the purge valve/hose as said in this thread. As AMFixer said and also my AM rep. up here, if the purge valve is not working as it supossed to, the tank can't mantain pressure to send gas to the engine, making the car stall. That is why it happens mostly from half a tank to full.

 

Telum01: Also, if you have a reflash of the computer in your car, it makes it worst. The new programs have new pressure parameters. I have a friend that had to return to the stock program. I'm thinking of doing that to in the meantime.

 

Sorry but I think you might be confused here. I try and explain the best that I can.

The purge line in the tank and the purge valve, all work together in a system to purge fuel vapors from the tank. If the hose inside the tank tears/breaks, then when the system does its purge cycle, it sucks fuel into the engine. Depending on how bad the tear/break is it could be a lot for fuel of just a little. When the fuel reachs the engine it is considered unmetered fuel, just like when you have a vaccum leak it would be unmetered air, but with fuel. The fuel did not come in from the fuel rail which the ecm monitors as it goes into the engine. Then the o2 sensors read the rich or unmetered fuel causing the ecm to try to correct for the probelm and thats when the stumble happens. The ecm will try and lean the system out or remove fuel to correct the issue. The reason it happens at a full tank to half is that the line connects to a hard line at the top of the tank. So has the fuel splashs around it gets inside the line. This system is more of an emissions system.

The fuel pump will always drive to keep the fuel pressue in the rail as requested by the ecm. Nothing in the emission system has control over that. The only thing the emission system cares about is the fuel level in the tank. So that it may check for leaks, or fuel vapor leak.

You would only ever get a engine light if the tear/break of the purge hose is bad enough. Which the ecm will catch because it has tried to correct to the unmetered fuel in the engine, but can not correct the fuel trim anymore, without causing catalyst or engine damage. That is when codes like stuck o2 sensors or catalyst codes come up.