+- STD (https://www.superturbodiesel.com/std)
+-- Forum: Tuning (https://www.superturbodiesel.com/std/forumdisplay.php?fid=6)
+--- Forum: Engine (https://www.superturbodiesel.com/std/forumdisplay.php?fid=7)
+--- Thread: Fuel Pressure Gauge (/showthread.php?tid=4979)
Fuel Pressure Gauge - OneEyedWilly - 10-04-2013
I have a 84 300D, in the process of tuning it up, doing maintenance and up keep. I have been thinking about different gauges I could put in there and one was a fuel pressure gauge, though when i thought about it I came to the conclusion that it would be hard to do, the line going to the IP is a vacuum, is it not? the IP draws fuel from the tank. so how would it pressurize a line behind the pump? and its all steel line after the pump.
Any help or ideas are greatly appreciated.
RE: Fuel Pressure Gauge - Simpler=Better - 10-04-2013
It goes tank->clear prefilter->lift pump->main filter->injection pump->overflow return line to tank.
I *think* you should plumb your gauge in on the line supplying the IP near the fuel pressure regulator
RE: Fuel Pressure Gauge - bricktron - 10-04-2013
i assume there is a kind of pressure converter diaphragm which lets the fuel pressure push on some air that goes into the cabin, so the gauge side is far away from any substances, like a boost gauge. what is the name of this part, if i'm correct that it exists?
RE: Fuel Pressure Gauge - Tito - 10-04-2013
Well, my exhaust boost gauge just pushes exhaust gas to the dash, and the original oil pressure sensor from my w123 flows oil to the dash. As long as it's not leaking, I see no problem. Even the brittle old plastic plumbing stayed intact after removing my dash.
RE: Fuel Pressure Gauge - Simpler=Better - 10-04-2013
You can also get electric sender gauges. I know the old (70s/80s) Ford trucks had electric gauges, and the 300SD models use electric oil pressure gauges.
RE: Fuel Pressure Gauge - MFSuper90 - 10-04-2013
9 out of 10 mechanical gauges just push straight fuel to the gauge via copper or plastic tubing
RE: Fuel Pressure Gauge - Simpler=Better - 10-04-2013
If you're worried about diesel in the cabin (I'm not) you can always stick the gauges through the hood or under the wipers
RE: Fuel Pressure Gauge - OneEyedWilly - 10-04-2013
Well I know they have Isolators that have a diaphragm that, on the cab side, use a mixture of anti-freeze and water to transfer pressure.
but what i am saying is that the fuel coming from the tank is basically a vacuum. Because the IP draws it from the fuel tank. SO, my issue is how will a suction push fuel up a line that breaks off from main line?
I know the return line is pressurized but the fact that its after the pump means I really wont be getting the info that I am looking for.
RE: Fuel Pressure Gauge - Volker407 - 10-05-2013
Do you want to measure the vacuum or pressure side?
The fuel changes from vacuum to pressure state in the presupply pump.
Gruß
Volker
RE: Fuel Pressure Gauge - OneEyedWilly - 10-06-2013
I didnt know there was a presupply pump? if there was it would have to be inside the tank. is there one up in there?
RE: Fuel Pressure Gauge - Simpler=Better - 10-06-2013
The lift pump is mounted to the side of the injection pump, it sucks from the tank.
RE: Fuel Pressure Gauge - OneEyedWilly - 10-06-2013
I know, But, if the IP is "drawing" fuel from the tank, how will it "push" fuel up a line to a gauge?
I know it would work if there was a pump at the tank. because it would supply pressure up to the engine and to the gauge.
its a difference of push, and pull.
RE: Fuel Pressure Gauge - Simpler=Better - 10-07-2013
Take a picture of your injection pump from the top and from an angle. I'll label where you probably want your gauge.
I don't think you're understanding what we have said so I'll try again:
The lift pump sucks fuel from the tank. The lift pump is the little guy on the side of the injection pump. The discharge side of the lift pump goes to the external spin-on filter. from the spin-on filter the fuel is then fed to the injection pump on the side that faces the engine. That's the line you probably want to tee into (it's pressurized). The fuel then goes into the pump, does it's thing, and excess fuel drains back to the tank.
The lines from the tank to the lift pump aren't pressurized.
The line from the lift pump to filter to injection pump are pressurized. I would suggest adding the gauge after the filter and before the pump, this way you can monitor fuel pressure. a clogged filter, worn fuel regulator spring, or tired lift pump will show low pressure.
RE: Fuel Pressure Gauge - OneEyedWilly - 10-07-2013
Thank you, I dont know why I didnt understand before, but I got it now.
Thank you, Gents.
RE: Fuel Pressure Gauge - Simpler=Better - 10-07-2013
(10-07-2013, 01:42 PM)OneEyedWilly Thank you, I dont know why I didnt understand before, but I got it now.
Thank you, Gents.
Anytime. We will beat it into your head :p