VS stalling

[finch21]

I have a vs commodore ute and it stalls whenever i brake and the car has almost stopped, but only when the fuel tank is full and usually stops once the fuel is down to 3/4 full can anyone help me with this.
Thinking it could be the fuel pump, vacuum leak or possibly the IAC Valve

[hako]

I've heard of this on older cars when the brake booster had a fault which was usually a split or otherwise damaged vacuum hose. Why it would happen only at certain fuel tank levels beats me. I'd also clean the throttle body and the IAC valve. Probably not the fuel pump as they usually fail totally. Auto or manual?

[finch21]

Its an auto my friend had similar problem in his BMW turned out to be problem with the brake booster. Don't know if it matters but only happens when its in gear idle doesn't drop if it in park or neutral with the brake pressed down

[hako]

I have a vs commodore ute and it stalls whenever i brake and the car has almost stopped, but only when the fuel tank is full and usually stops once the fuel is down to 3/4 full can anyone help me with this.
Thinking it could be the fuel pump, vacuum leak or possibly the IAC Valve

When you say "but only when the fuel tank is full and usually stops once the fuel is down to 3/4 full " - do you mean the problem starts then or never happens when the tank is below 3/4.
Reason for asking is that it's not unusual for utes to have this problem when cornering with fuel level below ~ 1/2 usually after the fuel pump has been replaced and the return lines stuffed up. The fuel pump sits in a swirl pot which is filled by the fuel return line when the tank level is below about 1/2.....if the pipe is dislodged the swirl pot empties when cornering and doesn't get topped up by the dislodged return line. I'd guess the same would apply when braking ???

Hope the above makes sense.

[finch21]

that does make sense i wish that was the problem but it only stalls when the tank is between 3/4 and full never any lower then that. I tested this the other day by filling it, took it for a drive stalled around every corner, then took ten litres out of the tank drove it again and it didn't stall once and hasn't since. Maybe just take it to a mechanic and let them sort it out

[greenacc]

The trouble is mechanics will charge a fortune for this kind of thing, cos most of them just keep replacing parts till its fixed, then charge you for all the parts when you didn't need most of them. Check all the vacuum lines you can find , fuel pressure reg, booster, booster hose, fuel line... Sounds like its related to engine vacuum, which is strongest when backing off throttle, ie under brakes. Clean the IAC valve and port too, and see if the problem is better or worse with the power button ON.