Fuel Level Sensing Flaky

[pbierre]

This is a 2013 XC70 T6, out West, virtually no rust, 114K miles. Over the past year, the fuel level sensing has gone flaky.
After filling the tank, it will show 1/2 full. But, a day later, it will show 3/4 full. During a drive, the display might start at 3/8 full, and then climb to 3/4 full.

I got my new iCarSoft Volvo/Saab V2.0 scanner, and it's seeing a

P134600 "Fuel Level Sensor B Circuit, General Failure. No sub type information"

Assuming this is a flaky electronic connection, can anyone detail the harness connections between the Fuel Sender,
Fuel Tank Module, and upstream path to ECM/CEM? thanks

[Steve H.]

I have had a strong dose 20 plus ounces of Techtron Concentrate fuel cleaner actually clean the contacts of the float switch contact strip. I saw this in a TSB but I cannot remember which manufacturer before. Might be worth a try.

[pbierre]

I have more info on this problem. The gas tank is nearly full.

When I start up the engine, the console bar shows the correct tank level 7/8, and the "miles to empty tank" shows 380 miles (correct).

About 15-20 seconds later, the tank level bar spontaneously jumps to 1/2 tank, while "miles to empty tank" holds at 380 miles.

After another 20 sec, "miles to empty tank" jumps down to 200 miles (would be correct if tank were 1/2 full).

Has anyone dealt with this issue? What does the :20 sec delay until the tank misread suggest? It is 100% repeatable.

[Aviator]

The fuel level sender in the left side/ejector side of the tank is shot. You need a new fuel tank.

[pbierre]

The fuel level sender in the left side/ejector side of the tank is shot. You need a new fuel tank.

Can you explain a little bit more how you arrived at that conclusion?

[Aviator]

The sender on the left side of the tank gets fouled with dirt and starts to stick or break. There is no access to that part of the tank...only the right side where the fuel pump is. Also, the plastic fuel lines in the tank sometimes kink and break. The tank is non-serviceable, except for the fuel pump. It's not a real frequent issue...maybe see 3 or 4 a year in the P3 cars.

[pbierre]

The sender on the left side of the tank gets fouled with dirt and starts to stick or break. There is no access to that part of the tank...only the right side where the fuel pump is. Also, the plastic fuel lines in the tank sometimes kink and break. The tank is non-serviceable, except for the fuel pump. It's not a real frequent issue...maybe see 3 or 4 a year in the P3 cars.

I take it you work on P3s. I'm perplexed because everything I'm seeing in online documentation for 2013 XC70 AWD "saddle" fuel tank indicates a single portal (fuel pump and level sender integrated into the same assy. 31372880). [ I previously had a 2004 XC70, and that had a saddle tank had 2 portals, fuel pump on passenger side, level sender on passenger side - and convenient access holes in the floor. ]

I agree that this P3 AWD makes it prohibitive to repair anything with the fuel tank, including the Fuel Pump Control Module (which they chose to mount on TOP of the tank). I would have to cut an access hole in the flooring to get to the module, and a different hole to get to the fuel pump. It's not that serious a problem, so I'll just live with it, and curse the engineers in Sweden for poor maintenance-design of the fuel pump / control module.

Thanks for taking the time to respond.

[Aviator]

"I'm perplexed because everything I'm seeing in online documentation for 2013 XC70 AWD "saddle" fuel tank indicates a single portal (fuel pump and level sender integrated into the same assy."

That is correct. The level sender on the left side is not shown because it is not serviceable. Your 2004 has a level sender on the left side as well...hence the access cover. Plus, the opening is used to pull the fuel transfer tube and ejector over from the right side/pump side.

[pbierre]

"I'm perplexed because everything I'm seeing in online documentation for 2013 XC70 AWD "saddle" fuel tank indicates a single portal (fuel pump and level sender integrated into the same assy."

That is correct. The level sender on the left side is not shown because it is not serviceable. Your 2004 has a level sender on the left side as well...hence the access cover. Plus, the opening is used to pull the fuel transfer tube and ejector over from the right side/pump side.

So, the 2013 AWD saddle tank has 2 level senders, one on each side?...the left side sender welded into the tank? OK.

Still learning about these cars (have 2 of 'em).

[Aviator]

"So, the 2013 AWD saddle tank has 2 level senders, one on each side?...the left side sender welded into the tank?"

Yep! All Volvo saddle tanks have a level sender on each side.

"Still learning about these cars (have 2 of 'em)."

The more you learn about them, the more you'll realise that your '04 was a much better car. The P3 cars are Fords. And, the P5 cars are even worse.

[pbierre]

"So, the 2013 AWD saddle tank has 2 level senders, one on each side?...the left side sender welded into the tank?"

Yep! All Volvo saddle tanks have a level sender on each side.

"Still learning about these cars (have 2 of 'em)."

The more you learn about them, the more you'll realise that your '04 was a much better car. The P3 cars are Fords. And, the P5 cars are even worse.

My '04 XC70 2.5T??....It had a fuel tank LEAK, a micro-crack in the plastic weld where the vent hose bib is attached. If you filled the tank to full, it would drip raw gasoline until
the level worked down to 7/8. I had the rear seat out, portal covers off, had it pressure-smoke tested to pinpoint the leak. I plastic welded my own repair, then sold it.
I've enjoyed owning two P3s, including doing all the maintenance and repairs (thanks to VolvoSweden on YouTube). The Ford-Volvo collaboration?....too much emphasis on software, leading to releasing new cars with minor, but annoying bugs. The software updates are way too expensive, so forget it.

When Volvo gets done replacing metal parts with plastic (the major trend toward lower weight lower reliability), it will be a very frustrating experience for owners -- maybe pushing them toward renting from the vendor. I stayed with Volvo bc I've got 35 years of experience working on them -- it's a hobby. The XC70 T6 is a rocket-luxury station wagon -- practical and fun to drive....excellent for road trips. Drove my T6 all the way cross country, coast to coast.