I was working on an old Jaguar (72 XJ6) with an aftermarket fuel pump running 6 psi. To much pressure and it pushes past the floats and the carbs (dual strombergs) puke fuel. So i bought a Autozone regulator and fuel pressure gauge to dial in the pressure. Tested pump pressure and the gauge (1-15psi) was only reading 2 psi. Knock it a bit and it would go between 1-5 psi.

So, i started reading up on gauges came to find out most gauges bought in the stores arent accurate at all. They can be off by as much as 20%. But there are rated gauges that tell you there specs i.e.. 3/2/3 Basically saying that basically this gauge is most accurate within 60% of its working pressure--the other common rating it 1.5% within the swing. AND--they are usually cheaper than store bought gauges!!!! There is alot to be learned about gauges that i couldnt possibly cover here.....but wanted to let you know

So i looked up gauges and bought (Grainger) a 1-5 psi gauge rated at 1.5% accuracy. What did i find--the regulator was bad also and or just a POS (pressure would turn on--then off--then on--then off--it wasnt constant. and was going to max pressure to nothing...

Moral--i will be replacing all my gauges with rated ones from here on out. I dont see how businesses get away with selling these crappy gauges--imagine tire pressure gauge being 20% off.....

Anyways--now you know--and knowing is half the battle

 

Three different tire gauges will usually give you three different readings on the same tire.

Reminds me of a quote:

"A man with one watch always knows what time it is. A man with two watches is never quite sure."

 

^ yep - NEVER carry two compasses! LOST!

 

yeah, the garbage that being sold in this country can be more work than the cheap price is worth. If you need a decent pressure gauge, precision gauge ,at least the last one I had my hands on, was made in the united states and 2% accurate. Napa can order a few of them here. I ve also had luck with shraeder-bridgeport tire gauges, there within a pound or 2 of eachother.

 

Grainger carries them and there are online carries Gauges.com i do believe, that carry them for about half the price. The one i got was accurate to 1.5% of the swing.

That reminds me of another saying (English) "I cant afford to buy cheap"

I think--just like cigarrettes, manufactures should have to put a warning on measuring devices stating their accuracy.