Hi Everyone,

I have a 1999 S40 B4204T and I've been experiencing a problem where the car will cut out after the tank reaches 40L of fuel. After the car cuts out, sometimes it wouldn't start again until more fuel is poured but other times it will start after several attempts.

Initially the problem was evident when the tank reached 20L and progressively got worse and worse. Up until now I was just pouring fuel before it got to 40L on the gauge as the car works normally with a full tank but I think it's time to fix it.

With a full tank, I've checked the pressure at the rail and it's 310 kPa as per the specifications. Residual pressure is ok too and only losing approx 10 kPa after an extended period. I've also checked the pressure at the filter and that is was approx 450 kPa which again is within spec.

When the car wouldn't run / start I checked the pressure again both at the rail and at the filter but this time the results were very different. At the rail the pressure was 110 kPa and at he the filter the pressure was 550 kPa

I've already swapped out the rear pressure regulator (fuel governor - part 30851005 which is a essentially OEM Weber RPM73) based on the troubleshooting steps in VIDA but that had no impact on fixing the issue.

I did a scan with VOL-FCR and there was a DTC and the description said "short-term fuel trim changing too quickly". I can't remember the code through.

The fuel filter was changed earlier this year and I've done about 10000 KM since.

I was thinking of changing the front pressure regulator it but it doesn't make sense that it will fail only under specific conditions.

The next thing I was thinking of doing is to take out the pump and sender unit to check for any blockages and give it a good clean or even changing the filter on the bottom of the send unit.

What are your thoughts?

 

I'm with you, remove the pump for a look.

 

Planning to remove the pump assembly on the weekend. I'll revert back with what I find.