Fuel Pressure Gauge Problem

[roosterdiesel]

My gauge showed 65 psi engine off -mad when I was going to drain the water from the filter. Figured it was trash in the regulator not letting it bleed down, drained it and needle didn't move. Turned key on and off a few times and it was pegging out after the second. Then I removed the gauge from the hose and it was still at 65psi. Anyone else have a liquid filled gauge do this? Mine's a Marshall.

Man, 92,500 and the gremlins came out! My buddy is trying to tell me trade off.....never! I love my truck!

 

[CHPMustang]

Wonder if the tension spring within is shot? Normally it would settle back to zero with no pressure applied.

 

[whatabudro]

Wonder if the tension spring within is shot? Normally it would settle back to zero with no pressure applied.

I've had 5 different fuel pressure gauges on the nova. I thought it was bad luck at first, now I just think they're all crap no matter who's brand name is on them. And these were low pressure gauges because of carburetion. I've had them read 8 psi with no presssure, 3 psi @ 8 psi, then every psi on the gauge no matter if pump is on or off. Just chunk it and buy a new.

 

[roosterdiesel]

I'm not having much luck finding one on a Saturday! :td: Well now off to drop the tank, hopefully the rain subsides long enough!

 

[Shraderman]

I've had other liquid filled gauges do this. I had a setup of Autometer gauges on a pillar mount. It turns out not to be the gauge at all, it was me. I installed it in the hot sun (Alabama) so that when the thing heated up, it gave an incorrect reading. Likewise in the cold winter, it was in error the other way. Turns out that the culprit was the little vent plug in all of the liquid filled gauges. I didn't remove it / drill a small relief hole in it. When the fluid heated up it compressed the inside of the gauge housing. Likewise in the winter when it got cold, it tried to draw a vacuum on the inside of the gauge. The burdon tube in the gauge reads pressure relative to the inside of the gauge, hence the error. If you have a liquid filled gauge, I'd bet there is a fill/vent plug somewhere on the top of it. The other problem that I got when I "fixed" this one is the oil from the gauge seemed to migrate all over that side of the dash and down on the floor. Liquid filled gauges are really good for severe service and vibration resistance, but may not be practical in a daily driver.

Anyway, that's my 2c worth.

ShraderMan

 

[BIG JOE]

FWIW.... I'v gone thru the same hassles with fuel press. gauges on race motors. This time 'round, I used a Gauge Isolator. Fits in-line between a OEM port on yer fuel filter houseing. Operates on real fuel pressure on the input side, Glycol on the gauge side. The Glycol eliminates temp issues. Also... IF the gauge diaphram did fail (Blow), you won't have DEZEL fuel spray'n 'round in yer cab. (Less than an ounce of glycol in the line)



JOE

 

[roosterdiesel]

My gauge is mounted under the hood so I'm not worried about diesel inside. I ordered another gauge from Napa, $19.89+tax...part #701-2036. I'm working on a bracket to mount it on the cowl so I can see what's going on when fuel is demanded. A nice matching AutoMeter gauge inside would be nice but I'll go the cheap route for now.

 

[roosterdiesel]

Well got the new gauge installed.

Looks like the water may have weakened my fuel pump. Only reading 59-60psi at idle and that's shimmed .075! We'll see what happens in the next few days.