Fuel gauge sticks at 1/4 full
Discussion
Just noticed that my ’07 Boxster (987) has a fuel gauge doesn’t fall below the ¼ tank mark. I discovered this after my car kept conking out while showing a fairly healthy amount in the tank. It fills up alright, and there’s no problem with the dial sticking elsewhere – only when it gets to the ¼ full mark.
An independent mechanic did a preliminary check using the diagnostic laptop, and found no fault, so that’s good news. Only thing is that I’m taking it in tomorrow to the mechanic for a proper look to ensure it’s not a problem with the cluster.
Anyone had a similar problem with their Boxster?
An independent mechanic did a preliminary check using the diagnostic laptop, and found no fault, so that’s good news. Only thing is that I’m taking it in tomorrow to the mechanic for a proper look to ensure it’s not a problem with the cluster.
Anyone had a similar problem with their Boxster?
mollytherocker said:
I am struggling to get my head around that one!
I'm borderline simple when it comes to all things mechanical, so all I know is that the mechanic took a badass-looking laptop to the car, fannied around with it, came back and said nothing problematic showed up on the diagnostic test, but a deeper examination is required to rule out a problem with the cluster.All of which is Greek to me, but was hoping you folks could lend your knowledge/experience to clarify what might be at fault here, as I know that a replacement cluster is mighty expensive.
Hi OP, I had this problem on my 986 Boxster and it's not an easy fix if it's the same problem. I asked the OPC Guildford to check for a similar fault to yours but my gauge used to get half way then fall to zero and show the reserve fuel lamp, you had to refuel to full to make the gauge come back up. The OPC said the cluster was at fault and that would be £1000 just for the part sir.
Right so I didn't believe them and proceeded to investigate myself. I removed the sender unit from the tank and inspected on the bench with a magnifying glass and ohm meter only to find there was a crack right across the circuit board. it's a real piece of plastic crap with a circuit board attached sending a resistance measurement back to the ECU. So ordered a new sender unit moaned at OPC and got them to fit and re-calibrate at reduced cost as they had mis-diagnosed the fault.
Right this is where it gets interesting so bear with me here. I was looking for the route cause of this fault and knew that I was having problems when filling the tank with fuel. Upon removal of the filler cap there was from time to time a massive intake of air past my hand holding the cap and into the tank. This had caused the bottom of the tank to implode to an extent where it had crushed the fuel sender unit and caused the crack in the circuit board.
The cause of the vacuum was a fault in the vapor gathering system valve EVAP that hides under the drivers wheel arch.
My suggestion would be to get an independent to check the resistance is being output correctly from the sender and take it from there. Then if the sender is broken, look for the reasons why? and check for a vacuum in the tank particularly when it is nearing empty of fuel as this is when I noticed mine the most.
Good luck.
Right so I didn't believe them and proceeded to investigate myself. I removed the sender unit from the tank and inspected on the bench with a magnifying glass and ohm meter only to find there was a crack right across the circuit board. it's a real piece of plastic crap with a circuit board attached sending a resistance measurement back to the ECU. So ordered a new sender unit moaned at OPC and got them to fit and re-calibrate at reduced cost as they had mis-diagnosed the fault.
Right this is where it gets interesting so bear with me here. I was looking for the route cause of this fault and knew that I was having problems when filling the tank with fuel. Upon removal of the filler cap there was from time to time a massive intake of air past my hand holding the cap and into the tank. This had caused the bottom of the tank to implode to an extent where it had crushed the fuel sender unit and caused the crack in the circuit board.
The cause of the vacuum was a fault in the vapor gathering system valve EVAP that hides under the drivers wheel arch.
My suggestion would be to get an independent to check the resistance is being output correctly from the sender and take it from there. Then if the sender is broken, look for the reasons why? and check for a vacuum in the tank particularly when it is nearing empty of fuel as this is when I noticed mine the most.
Good luck.
mollytherocker said:
£1k for new clocks? People's experience on here does seem to suggest that this sort of 'put new everything on' process is the norm for OPCs.
Yep I'm afraid so it's called an LRU replacement (Line replaceable unit) Its the minimum level they go to and should save time if they get the correct unit replaced first time. There are companies that repair the clocks and other bits of the car actually get down to the small detailed part that is broken and costs 5p.Gassing Station | Porsche General | Top of Page | What's New | My Stuff