99 V70XC fuel gauge on dash up/down and ignition switch

[PatternFlyer]

I just replaced the brake pedal position sensor to clear ECM-9400.
Tried opening the old one that shoed 0 ohm, but wasn't able to open it up after 1/4" hobby knife inserted around the cover side. Had the new ATE sensor, just wanted to see if I can save the old one.

Anyway, after replacing the sensor, I scanned the system to make sure the code is gone. Yes. it is gone.

Now. back to the question of fual gauge on the dash. With a new pump waiting for me to drain and install & ejector/sender unit not working, I had the fuel gauge showing somewhere between 6 to 7. It went down to not working at all.

Scanning showed DIM-0004 for the fuel level sensor (signal Missing). Then, I just wanted to test and started cranking a few seconds, turn key on position 2 and repeated a couple times.

Fuel gauge came up to where it was before for a few seconds and went down to nothing.

Cranked again and stopped a couple more times. Then same thing happened.

I've tried shaking the car left & right. (driver side spring still old one). Tried again, but no change.

Any one had fuel gauge moving up & down like this?

Can ignition switch cause this? I've had 1 incidence that the ignition switch kinda locked in the middle a while ago. Since then, sometimes it stops between position 1 and 2.

Is the URO part good ?
https://www.fcpeuro.com/products/volvo- ... vo-9447804

[rrres]

I don't know the answer as to why the fuel gauge is acting up but just to cover the basics...Is the battery in good condition and fully charged?

[PatternFlyer]

Yes battery is good & fully charged. It cranks good.
It is something that I never thought of.

[Grantkat]

PatternFlyer,

Caveat - I am not particularly familiar with volvo's take on fuel pumps. However I have had many Saabs prior to my volvo and they were famous for this issue - 9-3's in particular. If these function similarly then what may be happening is the guage jumps up during initial system check but then lack of a signal from the sensor causes it to drop.

here are some things you might consider:
1) - issue with the fuel sending unit. one would be the contacts on the unit. over time they can wear out or develop dead spots.
2) - wiring - obviously corrosion BUT also check the grounds. A bad ground can potentially cause this - in the Saabs the system performs a check of the guage (hence the guage jumps up) but then there is no signal from the sensor so it drops to zero.