vibrating fuel gauge needle-question

[swifter]

Does a vibrating needle on a cowl mounted fuel pressure gauge mean anything??? 30 motor,Holley black pump brand new,Brand new big port Magnafuel regulator, car is dedicated drag car so 1/4 mile at a time,under w.o.t. my son said the needle goes between 6 and 8 vibrating back and forth,idle setting is 7.5 -Normal ????? -10 lines from cell to regulator and -8 from regulator to carb- anything irregular ???? Steve

 

[Johnny Mac]

This is why they make the liquid filled gauges. Vibrations and pulsation even from the fuel pump can cause the jumps of the needle..that's their disadvantage. The liquid ones on the other hand read incorrectly once they heat up. Its a lesser of two evils game. You can run a small one on the fuel rail for double redundancy or double check it at the carb. But I wouldn't spend money on another cowl mounted one for a little needle bounce.

 

[6pk2goDemon]

Is it a liquid filled FP gauge ? They're very accurate and shouldn't fluctuate like that....

 

[Johnny Mac]

Also forgot to mention a dead head fuel system in my experience is more prone to needle bounce. But if its only at Wot...I wouldn't worry about it.

 

[swifter]

Not liquid filled,Just didn't know how to answer my son (driver) never had a fuel gauge mounted on a cowl,I'm glad its there but was just wandering about the bouncy needle-Thanks Steve

 

[swifter]

Yep only at w.o.t. at idle its steady-Steve

 

[Johnny Mac]

Yup. Don't worry about it. I personally would monitor it for idle setting and for major drops during passes. Good luck this season.

 

[swifter]

Thank you