Fuel Gauge odd readings

[romeroom]

2003 Vibe AWD With a similar problem as viewtopic.php?t=30913" onclick="window.open(this.href);return false;

BACKGROUND: My son wanted a bright LED version of the 2005. He bought a used 2005 cluster to later find out it would not interface as the 2003 because of the addition of a separate plug. Fair enough. So, he connected the 2005 plug that fit to the 2003 "to make sure it worked" before returning/reselling.

THE PROBLEM: After reconnecting the original, PROBLEM FREE, 2003 cluster, the gas gauge is--I'm assuming--not working properly. The car had nearly a full tank of gas before the ingenious cluster swap attempt. Now after a handful of miles, the fuel gauge is displaying almost a quarter tank left. The car is running great.

Would unplugging the battery for a while reset anything?

Some help would be appreciated. Thanks.

Once the gauge shows near empty, I will fill up to see how many gallons it takes.)

[romeroom]

Now my son tells me that the fuel gauge drop from nearly full to nearly empty in a few short miles existed prior to the cluster switch.

Here are two additional things that were done on the same day as the cluster swapping event.

1. Oil change
2. Spark plug replacement. (Replaced with Bosch 7957. I understand these may be a substandard choice. So, If you think this choice of plug is the real issue and likely to destroy the engine if I run it another mile, please say so. I'm am even open to a suggestion of a better plug to use. However, I find it hard to believe that such a plug choice would result in a gas mileage that closely resembles an RV.)

Thanks.

[JohnO]

I had a similar issue with the fuel gauge on my Chrysler minivan. It would drop quickly from full while driving and was generally erratic. It turned out to be a plugged vent line for the fuel tank. The fuel pump was pulling a vacuum on the plastic tank and the tank was getting crushed. You can easily check for this by removing the fuel cap after driving a few miles. If this is your problem you will hear a lot of air entering the tank as the cap is removed.

On the spark plugs, no need to change them quickly. They just are not going to last very long anyway. If they do cause a problem it will be a misfire.

[CharlesinGA]

Best plug choice is that listed in the owners manual. Yes, they do give you the plug part number in there. Mine lists a Delphi plug (which is what was in the engine from the factory) and also lists a NGK plug number. Bosch is a good plug, I have used Bosch in a 2.0L Plymouth Breeze for many miles before I sold it, and also about three sets now in my Ford Ranger 2,3L, but since the OEM Delphi works so good, I would stick with it next time you change it.

Since you mention oil change, it by chance isn't way over full on oil is it? The engine originally was 3.8 qts and Toyota changed dipsticks to raise it to 4.2 qts. If you dumped 5 qts in it, that will kill the gas mileage since the crank is whipping up the oil. Oil over 10W-30 will also kill the mileage. Should be either 5w-30 or 10w-30.

There are several gas mileage discussion threads on this board, but filling the tank one time will tell you nothing. You will need to track the mileage over a long period of time. This car is difficult to refill consistently and you might get 28 one time and 36 the next for no apparent reason.

Charles