Using pressure as a fuel guage

[Yroc]

I have noticed that when I fill up the pressure will drop very quickly at first and then stay around 1500-2000psi. At first I thought I had a leak, but I have checked over and over for leaks (what's the best way to check for leaks? I used soapy water).

Is it normal for your pressure to drop quickly at first? I was thinking that maybe I had a very small leak that would only leak when it was really full and would stop when it dropped. I am usually down to 2000 from 3000 within 8-10 miles of driving, so it's hard to check for leaks when it's clear full.

[Curtis]

I have noticed that when I fill up the pressure will drop very quickly at first and then stay around 1500-2000psi. At first I thought I had a leak, but I have checked over and over for leaks (what's the best way to check for leaks? I used soapy water).

Is it normal for your pressure to drop quickly at first? I was thinking that maybe I had a very small leak that would only leak when it was really full and would stop when it dropped. I am usually down to 2000 from 3000 within 8-10 miles of driving, so it's hard to check for leaks when it's clear full.


If it's not the fuel, it may be the fuel guage. On the Honda the guage is a temperature compensating pressure guage. I've had gasoline cars that would stay on full forever but race from 1/2 tank to empty like a cat with it's tail on fire. The likely hood is that there is an inaccuracy in your guage, but at the price the manufacturers charge, unless it's under warranty, you may want to live with it.:cool:

[Yroc]

I do have a fuel level guage that is just a bunch of lights, I assume they just represent the pressure in the tanks, but it could be a compensating guage?? But is does not seem to be. I also have an actual pressure guage that is in line with the tanks, I can see that under the hood when I fuel. I was really just wondering if the pressure goes down evenly as the fuel is used, or if there is a point where you start using more gas to get the pressure down.

[cngmike]

If you are fast filling you are witnessing heat of compression. gas expands with heat, the rapid filling of your cylinders causes heat. After the tanks have filled they cool and the gas in the tanks contracts showing a loss of pressure on your gauge. For instance the other day when i filled at work I filled to 3900 psi. The next morning my truck showed 3400 psi, I drove it a total of 200 yards.

[Yroc]

got it. Thanks, that's what I was looking for.

So all the quick fill stations should ALWAYS give us ATLEAST 3600psi. Getting 2500 or less and then watching it drop to 2000 just sucks...