My fuel gauge has started to slowly climb after the key is off so that if it is half a tank the night that I park it, by morning it will be reading just over 3/4 of a tank. Anybody else run in to this before?
MattZepyhrhills, FL
Fuel gauge wants to climb after sitting over night on a 1990 Q45
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mattd1979
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- Car: 1990 Pearl White Q45 plain Jane with 266,000 miles. 2015 moonlight white metallic Q70L with 20” wheels, sport brakes and a 5.6L at 58,000 miles.
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Re: Fuel gauge wants to climb after sitting over night on a 1990 Q45 (mattd1979)
Anybody have any ideas?
Re: Fuel gauge wants to climb after sitting over night on a 1990 Q45 (mattd1979)
Any idea which is the correct reading?
In 4 years of reading the NICO forum, I don't think I've heard of this one before, sorry. It's either mechanical or electronic.
I'm not sure how it could be electronic - it would imply that the sender could put out a lower or higher voltage, depending on whether the car is running or not. If it was electronic, I'd expect other things to be goofy. A bad battery or connection or alternator cause cause electronic gremlims, but they tend to affect more than one system when they do.
If it's mechanical, then I would guess the float gets stuck, and relaxes overnight, or something similar. If so, the morning reading would be the accurate one. But I'm not sure how driving around could cause it to read a 1/4 tank lower - a gallon or two, maybe, but 5 gallons seems too much.
Dunno. It's a new one.
In 4 years of reading the NICO forum, I don't think I've heard of this one before, sorry. It's either mechanical or electronic.
I'm not sure how it could be electronic - it would imply that the sender could put out a lower or higher voltage, depending on whether the car is running or not. If it was electronic, I'd expect other things to be goofy. A bad battery or connection or alternator cause cause electronic gremlims, but they tend to affect more than one system when they do.
If it's mechanical, then I would guess the float gets stuck, and relaxes overnight, or something similar. If so, the morning reading would be the accurate one. But I'm not sure how driving around could cause it to read a 1/4 tank lower - a gallon or two, maybe, but 5 gallons seems too much.
Dunno. It's a new one.
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mattd1979
- Posts: 710
- Joined: Fri Oct 29, 2004 6:08 am
- Car: 1990 Pearl White Q45 plain Jane with 266,000 miles. 2015 moonlight white metallic Q70L with 20” wheels, sport brakes and a 5.6L at 58,000 miles.
- Location: Jacksonville
Re: Fuel gauge wants to climb after sitting over night on a 1990 Q45 (96Qowner)
Just updating to say that the gauge still wants to climb when parked but it's not as fast as I once thought. I drive the car daily now and it doesn't sit as long to allow for the gauge to creep up as much. I notice that it creeps up maybe an eighth of the way the next day if I last drove it the day before. One time, it sat for about 3 days and I noticed that the gauge had crept up to almost 3/4 of a tank when it was actually between the 1/4 and 1/2 mark on the gauge.
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Q451990
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I have never heard of this before - but at almost 20 years old, anything is fair game.
Does the needle return to it's former position after you drive for a while?
I would read the FSM to find a good point to monitor the resistance coming from the fuel sending unit. That should narrow it down to an issue with either the sender or the instrument cluster.
Heath
Does the needle return to it's former position after you drive for a while?
I would read the FSM to find a good point to monitor the resistance coming from the fuel sending unit. That should narrow it down to an issue with either the sender or the instrument cluster.
Heath
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mattd1979
- Posts: 710
- Joined: Fri Oct 29, 2004 6:08 am
- Car: 1990 Pearl White Q45 plain Jane with 266,000 miles. 2015 moonlight white metallic Q70L with 20” wheels, sport brakes and a 5.6L at 58,000 miles.
- Location: Jacksonville
Re: (Q451990)
Yes, after you start the car, or just turn the ignition to the run position, it will come down to the actual level.
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Q451990
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So it's only inaccurate while the car is off? I'm not sure that I've ever paid attention to mine while the car was off anyway. I suspect there's something on the cluster that holds the needle at it's last position when the car is off - but I really have no idea. If it's accurate while power is supplied to the cluster and while the car is on, I don't know that I would spend any effort diagnosing it or trying to fix it.
Heath
Heath
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mattd1979
- Posts: 710
- Joined: Fri Oct 29, 2004 6:08 am
- Car: 1990 Pearl White Q45 plain Jane with 266,000 miles. 2015 moonlight white metallic Q70L with 20” wheels, sport brakes and a 5.6L at 58,000 miles.
- Location: Jacksonville
Re: (Q451990)
True. It was just a little annoyance to me I guess. I have a bigger issue which isn't that big really. I've got another fuel injector on it's way out.