Hooligan6

Which is better and more reliable electric or mechanical fuel pressure gauges?

Fisherguy

I went to mechanical without an isolator...

TonyB

Mechanical gauges are fine for single purpose. Electrical gauges can usually be switched between multiple sensors to monitor multiple functions, although not at the same time.

For electical gauges, your choices are wide and varied: Sweep angles, and transducer types

For the gauge itself, there are a two types:
1) Short Sweep: 90 degree
2) Full Sweep:270 degree

The short sweep gauges are similar to what you would have in the truck from the factory....the full sweep gauge gives more resolution across the entire gauge range. Autometer has a good illiustration: http://autometer.com/cat_gaugeop.aspx?sid=57

Then, there are 2 basic sending units for the gauge:
1) Single wire type. These are the easiest to wire, but lack accuracy. Accuracy for these sending units is tied to how well the sending unit is grounded. Any bad or poor ground between the sending unit and the gauge wil change it's reading. These are alse very sensitive to voltage fluctuations, such as the grid heater turning on and off, or headlights, etc.

2) The better electric pressure gauges use a 3-wire transducer (sending unit). What they do is send a reference voltage to the transducer that is isolated from the rest of the trucks electical system. The other 2 leads are the pressure signal and ground (return) to the gauge/transducer: These are run directly back to the gauge and are not influenced by voltage fluctuatuions in the trucks electrical system.
FYI...The better temperature gauges use 2 wires for similar reasons.

And...for fuel pressure you certainly do NOT WANT fuel to leak in the cabin. That's why isolators are used. Electric gauges get around isolators; they are their own isolator!

HTH

Tony

8mpg

I went electric personally.. Using an isolator is the correct way with a mechanical so if something happens, you wont have diesel inside your truck. You figure a mech gauge is $45, then the isolator is $75 and a hose is $30...you might as well spend $200 and buy an electric and not have to mess with it. Many people have issues with the isolators and trying to bleed them to get an accurate fuel pressure reading. Spend the extra $50 and get the electric.

Here is a write up I did of an electric install

http://www.savefile.com/files/822810

mgstroker95

Mechanical with out the isolater here. I have never had a issue with mine!

wlewis

Electric here. Mounted the electric sender on the firewall for good ground and to keep the engine from shaking it to death. Then ran a fuel line from a fitting on the banjo bolt at the intake of the cp3 to the sender. It shows the same pressure reading that a manual glycerine filled gauge I mounted at the fuel filter housing intake shows. As long as the filter is clean that is. If my electric gauge has a pressure drop at the cp3 and the mechanical shows higher psi I know the filter is plugging. Saved me twice now.