Fuel Level Sensor Gone Bad
08-30-2010, 10:07 AM
#1
Rennlist Member
Thread Starter
Fuel Level Sensor Gone Bad
Took a nice drive up by Poughkeepsie NY Saturday to watch my son scrimmage in football (they did great!).
I had my brother-in-law as well as my mother and father, and even though there were 4 of us, they demanded that I drive the 928 for the 130 mile trip up and back! I've got great family.
Car ran like a champ. Even used the aircon on the way back.
Only problem was the fuel gauge went all crazy on the return. I made it up there with 3/4 of a tank left. When I fired her up for the return, the gauge read empty. There was no puddle of gasoline under the car
, so I figured the gauge was wrong.
On Sunday, I pulled the fuel level sensor. It was a bit dirty with some brown powdery stuff here and there that cleaned right off.
I grabbed my trusty multimeter and measured resistance with the float at the top and bottom of its travel. Came out to 5ohms and 74ohms. Linear readings along the way too.
All seemed fine.
Reinstalled and took another reading - 45 ohms - all seems good. Stated her up and the guage read 1/2, then went to Empty. Started and stoped a couple times with no better results.
Now the reading at the sender was 112 ohms!
Not good.
Pulled it. Remeasured and it was now giving crazy ranges in the readings, like 90 - 160 ohms!
Time for a new sensor!
I had my brother-in-law as well as my mother and father, and even though there were 4 of us, they demanded that I drive the 928 for the 130 mile trip up and back! I've got great family.
Car ran like a champ. Even used the aircon on the way back.
Only problem was the fuel gauge went all crazy on the return. I made it up there with 3/4 of a tank left. When I fired her up for the return, the gauge read empty. There was no puddle of gasoline under the car
, so I figured the gauge was wrong. On Sunday, I pulled the fuel level sensor. It was a bit dirty with some brown powdery stuff here and there that cleaned right off.
I grabbed my trusty multimeter and measured resistance with the float at the top and bottom of its travel. Came out to 5ohms and 74ohms. Linear readings along the way too.
All seemed fine.
Reinstalled and took another reading - 45 ohms - all seems good. Stated her up and the guage read 1/2, then went to Empty. Started and stoped a couple times with no better results.
Now the reading at the sender was 112 ohms!
Not good.
Pulled it. Remeasured and it was now giving crazy ranges in the readings, like 90 - 160 ohms!
Time for a new sensor!
08-30-2010, 10:37 AM
#2
You can jump the harness that plugs in to the sensor and watch the gauge works good, then you know it is the sender. Don't remember the sequence but jumping all three leads in different sequences isn't going to hurt it. If the gauge jumps to full on one of the jumpings, there ya go. Sender.
08-30-2010, 11:43 AM
#3
Rennlist Member
Thread Starter
Good idea Sean, I didn't think of that. Although I'm 1000% sure my sensor is crapped out, this would be an excuse to open my drawer of electronics and use a variable resistor to see what signal the gauge wants at a few different points.
I originally read a range from the sensor of 5 ohms to 74 ohms that I think was spec. But here's a good way to confirm. And to know what to expect a new sensor to measure out at.
I originally read a range from the sensor of 5 ohms to 74 ohms that I think was spec. But here's a good way to confirm. And to know what to expect a new sensor to measure out at.
