sjm

A couple of times now, after a short, shallow water crossing my fuel gauge reads full, and it slowly (5-10 minutes) returns to normal. The water is not deep - maybe halfway up the wheel, if that. And it's not long, only a few seconds. Everything else seems fine, no noticeable issues other than the gauge reading full.

I understand the gauge is inside the fuel pump, which is inside the tank, and it works fine at all other times. It's only after a couple of water crossings that I've seen this occur, and after a few minutes, it returns to normal with no noticeable affects. Any ideas?

It occurred after both these crossings:


and

jgrote

My guess is electrical. I would bet that a plug is getting wet and thus creating a dead short. (0 ohms of resistance) This would peg the needle. Then the water drips out and things go back to normal. If you're not under warranty, take out the rear seat and follow the wiring coming from the F.P. It's got to be getting wet somehow. And remember, there are a few plugs involved with getting that wire to the front of the car, (FHI makes the wiring harnesses "modular" to make it easier to install) so the problem may not be near the pump.

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04 X a/t
00 L a/t w/ 200K!

dpm

and two sensors, one in each side of the tank, in series. They connect to the body computer, not the gauge, so the current in the circuit is likely to be very low and damp more likely to be an issue.

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2009 SH XCdiesel 6MT

sjm

Thread Starter

Thanks guys. I assumed electrical the first time it happened, but couldn't see anywhere where water could get in. I guess I need to have a more thorough look.

I have a full service manual and wiring diagram, and I can see the two sensors - fuel level and fuel sub level (page WI-162). And I understand the body computer reads the resistance, and the instrument cluster reads the value over the CAN bus. So apparently, I have an exposed connector somewhere between the BCU, the two sensors, and ground. That narrows it down pretty well.

And yes, I still have almost 2 years of factory warranty remaining, but I'm not adverse to tinkering...

Thanks again!

sjm

Thread Starter

Well I bit the bullet, and pulled the seat out - this is what I found! Yuck! I'm surprised the gauge was working at all given the difference between empty and full is only 29.9 ohms. The slightest amount of dampness on that dust would have a significant effect. Needless to say, it's now all cleaned and thoroughly waterproofed...

jgrote

What did you do to waterproof it? Did you take any pics of that?

__________________
04 X a/t
00 L a/t w/ 200K!

dpm

that's a lot of very fine and likely slightly conductive dust!

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2009 SH XCdiesel 6MT

rsay777

It looks like you have been having a GOOD time in your Foz.