Check Fuel Pressure With Mechanical Gauge?

[Cooker]

I have decided, at least for now, to not install a permanent fuel pressure gauge, but what is the best way to check pressures with a temporary mechanical gauge?

As I see there is a "test" port on top of the fuel filter housing. Is this 1/8" NPT? Then all I need is a liquid filled fuel pressure gauge in the 40lb range correct?

What is the "special" test port adaptor that TST sells? Is it necessary to check the fuel pressure?

Thanks for the help,
Ryan

 

[illflem]

Ryan, I have a mechanical fuel pressure gauge permanently installed in my cab. Did this after the sender on the electric one went out, cheaper and more accurate. I know that it's a no-no to bring fuel into the cab, but diesel isn't dangerous like gas, and I've been bringing motor oil into cabs for years with mech. oil pres gauges with no problems. The bleed screw you speak of is metric bolt thread, TST's adaptor is this bolt by 1/8" pipe, it also has a very small hole though it that acts as a gauge damper. You must have a damper or your gauge will be all over the place. I went another route by drilling and tapping the IP inlet banjo bolt top to 1/8 NPT, because it's easier to get to and is not in the way for bleeding fuel from the filter. Saves $25 also. Screwed a 1/8" gauge snubber(damper) $9 from a tractor supply into the banjo bolt, then went with a mech oil pressure tubing kit $5, to the gauge, 40 psi liquid filled rear connection from hardware store $12. Made the gauge holder with an L shaped piece of aluminum sheet with hole sawed hole for the gauge. Mounted it down by the airbag unit, center near the floor. Works great, cost less than $30 and took about 2 hours. Problem with a temporary gauge is that you need to runit into the cab to get readings while driving, by the time you do all that it might as well be perminate.

[This message has been edited by illflem (edited 03-19-2001). ]

 

[Andy Redmond]

The bleed adapter on the output of the fuel water seperate is a M6*1. 00 thread pitch.

I had one in a fuel psi kit for a gas application (wakeon kit). It converts the m6*1. 0 thread to a 1/4" male flare/JIC that allows me to thread my gauge hose on.

BTW I use a liquid filled gauge face to prevent the "violent" pulsing other rave about.

I have a gauge set I made up for a 12v application, although I like it better than the Miller kit, it cost more.

Good luck,

Andy

 

[Cooker]

Where is a good place to get a mechanical fuel pressure gauge?

Jegs has their own brand of liquid filled fuel pressure gauges for $20 with an 1/8" NPT fitting on the back. I'm leaning towards Jegs unless someone knows of a better deal.

Is a 30psi gauge going to be enough or should I opt for the 60psi?

Thanks again, Ryan

 

[illflem]

This is what I used.

http://www.grainger.com/Grainger/searchresults. jsp

Link doesn't want to work right now,$7. 95 from Granger for a 60#,liquid filled back mount stainless steel case.

[This message has been edited by illflem (edited 03-21-2001). ]

 

[C Schomer]

I silver soldered a 6mm bolt to the back of a 1/8" brass cap and drilled a hole thru it for the adaptor. I found a dampened 30# oil pressure gauge in my tool box and got some nycoil tubing and festo fittings from the supply room. I'll find out if it works this weekend! Craig

 

[pcorssmit]

Craig, if it doesn't work let me know, I tapped out the banjo bolt like illflem did (thanks, Bill) for 1/8-27 NPT. I don't have a permanant gauge, I just hook it up to the boost gauge when I want to check the pressure. I bought a new banjo bolt to replace the tapped one that I use when not checking the pressure. So the Tapped one is off the truck if you want to borrow it.

Pete

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'97 2500 CC 4X4 5spd Sport
'83 K5 Blazer 350 TBI (ex 6. 2), 39. 5 TSLs, 3" lift, Dana 60/GM 14 blt, Detroits

 

[illflem]

Pete, what Larry B did is hook in a three way solenoid valve to his boost gauge so he could toggle between boost and E-brake back pressure. Same thing could be done with boost and fuel pressure. Same idea you have in a permanent installation. You might get a little fuel in your intake,but I can't see a problem with that.

 

[Cooker]

I like this 3 way valve idea.

Can't you put an isolator in the fuel pressure line so the line will still read the pressure, but not carry the fuel past the isolator?

 

[illflem]

Ryan you sure can, problem is coming up with a decent price on a isolator. I found some for under $10 from a surplus house last year, posted it here and they sold out in a week.

 

[C Schomer]

Thanks Pete!

 

[C Schomer]

I can stop wondering about the overflow valve - 22# at idle and 30# at high rpm. Craig

 

[illflem]

Craig, my fuel pressure rarely deviates from 22 psi. If I punch it hard on a hill it will drop to 18, downhill with no throttle 25 psi. My overflow valve is stock, never been touched at 127k.
Could you have a kinked or melted section of return line?

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95' 25004X4,AT,Driftwood,Banks Stinger,Warn fender flairs and running boards(work truck)
95 3500,5 speed 3:54,BD E-brake,Driftwood,Banks&Psycotty,34,000 GCVW apple and tractor hauler(works harder truck)

 

[C Schomer]

Illflem, the lines all looked fine last fall and i've only put on 800 miles since! The pressure will even hit 32# the moment I let of the throttle! It run great! I'm not going to mess with it. Craig