Fuel Presssure Gauge!
 

So i bought a fuel pressure gauge so i can monitor my new lift pump... But the dude at Summit Racing said i need an isolator because the main pump can back pressure fuel and blow the gauge up because it will go to 200psi.... Sounds like BS! So do i REALLY need the CRAZY expensive isolator?

Using an Autometer mechanical gauge!

Thanks guys! :U:

Yeah he is blowing smoke your reading psi before the injection pump, just the lp which is 15 psi :c:

I think what he might of meant that the fuel gauge can get pulsation form the VP-44. I used a needle valve to dampen the pulses to my fuel gauge. So it wouldn't kill the sender my fuel guage is electric. But have seen snubbers used on mechanical guages so fuel is not brought into the cab of the truck.

John

Tap into it right there on the top of your filter cannister. You pull one of the brass plugs, forget which one is the outgoing side but whichever that is you want it and i think it's a 3/8 high pressure fittings or a brass fitting from the hardware store screws right into that. Connect your hose to that fitting and run it to wherever you want it to go.

You can even run to the home store and pick up a little shutoff valve if you want it also. But no you don't need an isolater unless your your tapping into the test port of the VP44 and that gains you nothin but problems.

I just ran mine in the cab without a isolator to the gauge in stainless steel line. I put my gauge on the steering column. You could just tap it off the fillter and run stainless steel line to the gauge you dont have to worry about air in the line with a isolator that you have to fill with anti-freeze and then bleed it. Your choice.I seen a welder weld a tank on a big rig with diesel coming out the hole. So if you are worryed about fire the flash point is very high on diesel fuel. Remember it is low pressure 0 to 25 psi depending on your fuel system .A shut off valve is a good idea if there is a problem just turn it off. I am not a welder so dont send hate mail ,it is just what I saw and was amazed.If it was gas cam2 or vp racing fuel this would be a different write up.

The only thing is that if you dont install the isolator - they likely wont warranty your gauge. That being said, Ive had fuel pressure guages with no isolators in both my trucks for 5 years and never have had any problem.

I will try to post some pics later tonight that are for a 99.

Ture with the warranty.All my gauges on my other cars have been auto meter pro comp(gel filled) gauges mounted on the outside and there still working today from (1998) and running 45 to 65 psi on them.You think that all manufactures of gauges would also make the diafram that is in the gauge to stand up to different fuels,anti-freeze,bio-diesel, diesel, water, ect,ect to last a long time.I will try to post some pics on mine.

Thanks for the info... I was hoping not to have to run a isolator. I will probably run a high psi hose of some sort... I cant really afford stainless... I am not too worried about a fire. I know how inflammable it is.

I actually have a gauge there already. A small one i got from Autozone. I wasnt going to use it but i had to during my diagnosis phase LATE last night. (dead LP). The guy i bought truck from updated lines to 1/2" and there is a port in the elbow on the VP. I was thinking about using that. Im all set for when i DO get all gauges because there is even a port w/ plug in it for the Pyro.

If you use that port down by the VP you will need an isolator or your gonna get some nasty needle bouncin from the pulses.

turbo20psi, do you know how to bleed the stupid isolator with antifreeze? My guage kit didnt come with and type of eye dropper thing to fill it. I'm replacing my airdog 90* line to the VP with a tapped one so I'm pretty sure I'll need the isolator.
Thanks

If i get a needle valve i wont need the isolator though right? Even if off the vp44 supply elbow? I can always use the OTHER port on the filter housing i guess... Kinda cool it has 2 ports... Ill switch the under hood gauge to pre-filter and the in cab to post filter.

x2. I have the Vulcan 1/2 Line from the Filter to the IP and it has that same fitting in the elbow. I ran a stainless braided line to the firewall and zip tied the sender there without an pressure snubber. The needle bounced horribly and killed my sensor(electric guage) in a matter of weeks.

Rather than an isolator you can buy a pressure snubber that has an orfice or a fine screen in it that will dampen the pulses and let your gauge live. Though being mechanical you probably won't have to worry about something breaking.

The main reason most people use an isolator on a mechanical gauge is so they can avoid running a fuel line inside the cab.

stick one end in a jug of anti frezze then suck on the other end , once you get some in your mouth stop and put your thumb over the end , then pull it out of the jug and it stays in the line as long as you dont remove your thumb .

find a neighbor kid or something

:lolleft::lol88:lol:woot::clap::D:ha:

I literally almost pissed myself when i read that!

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Where would on get a needle valve from?

I think im going to go in cab, no isolator. I need to figure out how to get the fittings together and what to use to run it in a cab using a needle valve as an isolator. Anyone have any write ups or info?

McMaster Carr

You could also try your local hardware store. However you want to make sure the one you get will be compatible with diesel fuel.

You could also go down to your local auto parts store and ask for a pressure snubber. The disadvantage there is you can't shut the line off if something happens to the gauge or you want to take it off.

Heres some pics of installs on a 99 - it uses the front port on the fuel filter canaister. Do you still have the filter canister or is it gone? Yours isnt stock so it will be a bit more of a custom setup.

Attachment 52054

Attachment 52055

Basically the needle valve goes between the sample point and the fuel pressure guage. Start the truck with the needle valve closed all the way and very slowly open the valve up until you get a steady reading (it should be barely cracked). Thats all there is to it.

Went to put my gauge on and the dang thing doesn't have a connection to fit the actual gauge fitting. Its -4AN and they purposely didn't include any fittings for that because they want you to buy their S.S. kit. LAME! So to get by i moved the little cheapo gauge i got from autozone from on top the filter canister into the cab using the line kit from autozone. Just some compression fittings and nylon line. NO leaks and works great. Because of the small line and the copper screen on the gauge i get NO pulsation! My new LP holds 12psi at idle and 10psi at WOT redline. :rocking:

I would still put a needle valve in there - for two reasons: 1) the pulses could eventually screw up your guage and more importantly 2) you dont want a fuel leak in the cab.

Very good point! I will get one from Mcmaster. I just wanted something in ASAP because i want to monitor the Summit brand pump closely!

You may have caught it in time.

Do you have a p/n?? Looked on there and some are pretty pricey.

if you go with a pressure snubber - make sure you get one for diesel (there are different ones)

DO I fill the guage itself with the tasty antifreeze?
And to bleed the fuel side of the isolator do i just loosen that screw and prime it by turning the key till I get fuel outta it?
Thanks, hoping to get this done tommorrow.

No I don't. I was just posting up a website that I know of that has needle valves. More'n Likely you could find a cheaper one at the local hardware/auto parts store. I have an electric gauge and didn't use a needle valve.

Ok, on Saterday I ried to finish the guage, I had a 15psi reading than it dropped to about 5 but I know I had a leak from the 90* elbow where the compression fitting goes into the nylon fuel line. So after an hour of it leaking when sitting I assume it got airbound an the truck took forever to start and the airdog motor was rapidly trying to prime.

On Sunday at work I fixed the leaks and bled the isolator and added more 50/50 antifreeze in the rubber hose to the guage from the isolator. The truck starts fine and doesnt leak but I dont have a reading.

Can I just use copper line or brake line directly to the guage and not use the stupid isolator?
I dont care about fuel in the cab and I heard of people not having prolems with pressure spikes during start up and I just want it to work.
Thanks!!:argh:

Of course you can - but you must make sure you do a good install.

Dont use copper - the vibration from the engine can cause the soft copper to break.

Just get yourself a 1/8" needle valve, some 1/8" DOT Approved air brake line (5 feet or so), and some 1/4" air brake line. The 1/8" line carries the fuel to the guage, and slip the 1/4" line over the 1/8" to protect it where the line goes through the grommet in the firewall.

The 1/8" needle valve should look something like this:

Valve,Needle,1/8 In - Needle Valves - Valves - Plumbing : Grainger Industrial Supply

But you may find one at your local hardware store.


The following info is courtesy of Infidel on DTR:

After the install start your
engine with the needle valve closed then open it slowly till someone in
the cab signals you that it's just reading pressure. If you tighten down
the packing nut under the valve handle the setting can't move. The valve
will control pulsation and buzzing and can also be shut down in the
unlikely event that you have a leak. Without a valve to restrict the flow
the gauge will pulsate so badly that you won't be able to read it in the
short time before it self destructs.

Parts list; 1/8'' needle valve - $2.50 from the hardware store, plastic
oil pressure tubing kit that comes with the compression fittings - under $10
from any auto parts store. 1/4'' tubing for protective sleeve - less than $2.
Gauge is your choice and may come with tubing. The pressure gauges I
use cost around $10 from here https://www.surpluscenter.com/home.asp , bringing the total cost to less than $20 and a
couple hours of your time.

This way sounds ten times better than the plastic tubing and isolator.
Will gather parts for this today and try and get it going as soon as I can. Thanks again!!!:c:

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Found something like a needle valve at my job today. instead of that turn screw its a bleed valve like on a caliper. Would this work or should I go elsewhere and get the valve you linked me too?
Thanks for the help!

No - you need a "needle valve" or pressure snubber (one for diesel).

ok thanks, will get one tommorow