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tbird650
23rd November 2011, 10:38 AM
I've been running a gauge for monitoring the internal lift pressure for some time now.
It's been a valuable tool for early warning signs and diagnosing various issues.

The gauge gives an audible "buzz sound" at times so I'm wondering if anyone else has such an item
and if they're getting similar sounds. Looking carefully, the needle isnt totally steady when the
buzzing occurs. Lately I've been taking more notice and I see the symptoms at the lightest of throttle and disappearing when the throttle is opened.
I reason that there could be tiny pulses in the lift pressure, possibly the harmonics of the high pressure end of the IP reverberating.

One thought is that the gauge is a cheap item and sound is from the small workings inside.
I think these have like a miniature rack&pinion setup which could easily account for the chatter.
I understand an oil filled guage is often used in industrial situations to overcome frequency pulsing so
that could be a fix?

Google some time ago turned up someone puzzling over the same phenomena.

Tony From West Oz
23rd November 2011, 11:36 PM
You most likely have fuel in the gauge line, all the way to the gauge.
Disconnect both ends of the gauge line and blow the fuel out from the gauge end. Reconnect the gauge end making sure you get a good seal. Then reconnect the fuel line end. The gauge should now be quiet and no swinging the needle at idle.
The chattering is causing rapid wearing the gears in the gauge so should be dealt with promptly.

Regards,
Tony

tbird650
24th November 2011, 06:52 AM
most likely have fuel in the gauge lineThat could very easily be the case. Having air in there would allow some cushioning I suppose??
The gauge was from an old air compressor. Would be a basic quality item at best.

tbird650
7th December 2011, 10:53 PM
Ok, to follow up, I forced air into the line, re-assembled and it's quiet now. Thanks. It worked well.

Tony From West Oz
7th December 2011, 11:02 PM
I had that issue in one of our 300Ds, it eventually destroyed the gauge for lack of action. Why my son did not come and tell me about it? I don't know.

That is how I know about the chattering fuel pressure gauge.

Regards,
Tony

tbird650
8th December 2011, 08:22 AM
Interesting co-incidence... I'd mentioned to a friend about the gauge buzz and said that
a gauge of the "oil-filled" type might be required to fix it.
After sorting the line to the gauge and posting here of the success, an oil-filled gauge turned up
in my letterbox the very next morning! He'd dropped it in on the way to work that morning.:)

Tim-HJ61
8th December 2011, 04:43 PM
Or spend up and get an electric gauge where the sender is only connected to the gauge with electrical wire and nothing can come up the line into the gauge, or worse, spray fuel inside your cabin.

Tim

tbird650
8th December 2011, 04:54 PM
or worse, spray fuel inside your cabin. A whisper I heard was it was illeagal here to have gauges with "live pressure fuel line" running into the interior of a vehicle. Diesel/vege could make a mess... but petrol could get ugly real quick.