Engine/Transmission (1994 - 1998) Fuel Pressure Gauge in 12 valve

[JHenry]

I recently put a Pricol fuel pressure guage in my '98 12v. It has an electric sending unit. I wanted a direct pressure gauge, but I went with the electric gauge because the guy on the phone asssured me that the "new" electric gauges were much more faithful than the old ones. I now have readings ranging from 2#s to 30#s. No pattern to the fluctuation. I realize the fuel pressure is not as critical on the 12v as it is on the 24v, but that is beside the point. Is this sort of range normal, or is my sending unit screwed up? It is installed correctly. Thanks.

 

[JFaughn]

I was planing on the mechanical gauge .
Not sure what you have , but from my info , you need a needle valve to get rid of the pulsating of the LP either way .

 

[hsmith]

Be sure to use the 60# gauge on the 12 valve and a needle valve to control the pulsation from the lift pump.

 

[HPetrat]

Was thinking about adding a mechanical fuel gauge to mine as well, but I was told that it was illegal to have fuel lines/tubes running into the cab of the truck that may expose passengers to fuel in the event of a fitting failure or accident .

I have not looked into whether or not this is true, any one else?



JFaughn/hsmith; when you say needle valve, are you refering to a snubber?





HP

 

[WDixon27]

what pressure you show depends on how healthy the OF valve is but it shouldn't go from 2 to 30, shouldn't flux more then 10-15# from cruise to idle, my truck got happy when i tweaked the valve to max out around 35-36# and it would idle around 26-27, my isspro 60# gauge crapped a month or tow ago and i need to replace it, you definetly need more then 30# if you don't want the gauge pegged just about all of the time, i had a 30# which was ok when the stock lift pump was mostly dead but when i installed a new one and it broke in the fuel pressure about doubled and i gained a crap load of power

 

[WDixon27]

i tried a snubber but even with the loosest insert it took maybe 5 miles of running for the gauge to reach operating pressure, a needle valve in place of the snubber fixed it right up

JFaughn/hsmith; when you say needle valve, are you refering to a snubber?





HP

 

[radcam]

Was thinking about adding a mechanical fuel gauge to mine as well, but I was told that it was illegal to have fuel lines/tubes running into the cab of the truck that may expose passengers to fuel in the event of a fitting failure or accident .

I have not looked into whether or not this is true, any one else?



JFaughn/hsmith; when you say needle valve, are you refering to a snubber?





HP

HPetrat I believe that most people that run mechanical fuel pressure gauges use an isolater that uses glycol (anti-freeze) for the liquid that goes into the cab of the truck. Basicaly all an isolator is is a diaphragm with the fuel on one side and a non flamable liquid on the other.



I would hope that no one is running fuel lines into the cab of their truck. Though my first couple of pick-ups had the gas tank behind the seat.

 

[Joe G.]

I tried some mechanical fuel pressure gauges. Didn't like them. My Westach gauge is electronic. It has been very reliable with over 200K miles on it. It is 40 PSI. My fuel pressure since installing an overflow valve from TST Products pegs the gauge quite a bit. I really don't care about the high end of the scale. More interested in the low end with things start to go wrong. I have installed a marine alarm pressure sensor so that a blinking light will come on if pressure is below 10 PSI.



You have to have a needle valve and/or snubber regardless of having a mechanical or electronic fuel pressure gauge to protect the sensor or gauge from pressure spikes. I use a grease gun hose from the banjo fitting on the input to the P7100 to the fender to isolate engine vibration from the pressure sensor.