Safe To Use?

crash-harris

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So what size are our fuel lines?

I'm thinking of using a brass tee fitting right under the drivers seat on the frame rail with hose barbs and a shutoff valve on it so I can plumb a braided hose into the cab to the fuel pressure gauge. That way if it ever starts leaking I could jump out, shut it off and continue driving.

In a million years when I do away with the mechanical lift pump and replace it with an electric one, I'll just move the whole thing to in front of the fuel filter.
 
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crash-harris

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3/8 sounds right from the looks of it. Now I just have to get on it. It's a toss up on doing this or a 3G alternator swap after I get the coolant filter in.
 

madpogue

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So what size are our fuel lines?

I'm thinking of using a brass tee fitting right under the drivers seat on the frame rail with hose barbs and a shutoff valve on it so I can plumb a braided hose into the cab to the fuel pressure gauge. That way if it ever starts leaking I could jump out, shut it off and continue driving.
Many years ago, I installed a mechanical oil pressure gauge in my Dodge Omni (okay, more like DECADES ago....) daily driver. I thought it (and I) was the shizzz, until the line leaked right at the gauge head. It was then that it occurred to me, any vital, flammable, or high pressure fluids used to operate the engine should NOT enter the passenger compartment (this is why your heater core is right on the firewall, and not piped way into the HVAC control panel area). Just get an electric fuel pressure gauge and run a WIRE into the cab. Worst case is that the wire will chafe and blow the fuse for that circuit.
 

crash-harris

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I've thought about this, although my entire reasoning behind mechanical gauges is to see data in real time, mechanically. Hence the shut off valve for the feed line to the gauge. Autometer also makes an isolator for in cab fuel pressie gauges, but I'm not sure how it works yet.

I have a mechanical oil gauge in Bruiser that leaked once, but it was due to my ignorance of compression fittings many years ago. Both trucks will also have air pressure gauges installed in cab eventually when I can get around to doing the on board air setup. Proper grommets and feed line routing will be observed. After seeing/knowing how we secure and sheath lines on the trucks at work, I have new ideas to keep things from rubbing.

Did you know that plastic corregated tubing will rub through steel over time?
 

snicklas

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...Did you know that plastic corrugated tubing will rub through steel over time?

Yep..... when I am working on it here soon, I will take a picture of where the choke and throttle cable go through the firewall on my 1650. The have made the hole at least twice original size, and they are tethered at the firewall..... the are a metal sheath.... but its amazing the damage a little vibration can cause.
 

madpogue

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I've thought about this, although my entire reasoning behind mechanical gauges is to see data in real time, mechanically. Hence the shut off valve for the feed line to the gauge.
"Real time"? Um, from an electric sending unit to an electric gauge head, the signal is going over a copper wire at something close to the speed of light. Over, what, 1-2 meters, you're talking nanoseconds (if that; I don't feel like doing the math...) of delay. If you could react to a change in the reading in that kind of time, you're pretty darn good. The wire from the sending unit to the gauge head could stretch once around the Earth, and it would only have a delay of one-seventh of a second (although it would make for rather tricky driving.....).

You won't be able to shut that valve in "real time". You'd be very lucky if it only failed at a time where it wasn't perilous to pull over and cut it off.

(Hmmm, now I'm actually wondering, when the pressure changes in the fuel line, would the change in pressure going down the branch to the gauge head actually happen faster than an electrical signal from a sending unit right at the line picking up that same pressure change? Again, we're talking nano- or maybe pico-seconds, but......)
 

fsmyth

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I'd say - it's the difference between knowing how to route your lines properly and
someone who hasn't a clue. ALL of my vehicles have at least one, generally 4-5,
mechanical gauges. No leaks. Usually, oil pressure, fuel pressure, and air pressure.
Mainly because of the difference in senders - it seems like I always have the wrong
one for the gauge :) And the numbers on the senders are hard to decode.
And I generally have a mech. gauge in the right range.
I will say - it's a pain to pull a panel in a Pete or Reo that someone has made a line
too short, though :(
 

crash-harris

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"Real time"? Um, from an electric sending unit to an electric gauge head, the signal is going over a copper wire at something close to the speed of light. Over, what, 1-2 meters, you're talking nanoseconds (if that; I don't feel like doing the math...) of delay. If you could react to a change in the reading in that kind of time, you're pretty darn good. The wire from the sending unit to the gauge head could stretch once around the Earth, and it would only have a delay of one-seventh of a second (although it would make for rather tricky driving.....).

You won't be able to shut that valve in "real time". You'd be very lucky if it only failed at a time where it wasn't perilous to pull over and cut it off.

(Hmmm, now I'm actually wondering, when the pressure changes in the fuel line, would the change in pressure going down the branch to the gauge head actually happen faster than an electrical signal from a sending unit right at the line picking up that same pressure change? Again, we're talking nano- or maybe pico-seconds, but......)

All the dash gauges are also electrical. Not much in the way of advocacy for those. I can deal with 7psi in cab for a minute if I have to for the simple fact that if a electrical sender fails, I'd be potentially stuck somewhere until I can replace the lift pump, in this case. May think of doing an electrical one after I get around to nixing the mechanical pump for an electric one. I've had to deal with much worse in places where I couldn't actually stop, like when I had to crap rig the gasser in the middle of the road after hitting a pot hole that killed the EEC-IV and multiple sensors (fixed but after going through everything I still can't find a definite cause).
 
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