I've got a kit coming but it evidently doesn't come with any directions. Does anybody have any step-by-step directions for a mechanical gauge with an isolator? Pics would be appreciated!

 

where are you planning on hooking up the fuel line and where are you planning on mounting your gauge?

a common spot to hook up is the schrader vavle on the VP44, or on the bottom side of the fuel filter cannister. both are good locations since you will be reading the pressure after the filter.

 

Typically the filter cannister works out the best, the closer you get to the VP44 the stronger the fuel pulses are gonna be that are hard on a guage and make an isolator mandatory. you don't really need one if you use the filter housing. There are step by step guides out there will just take me a little bit to find em and then I will be back.

 

Link from PDR's tech section: http://www.piersdiesel.com/TechIsolator.htm

 

Sorry for the delay.....Ive been meaning to get to this.

These instruction are for a purely mechanical setup with no isolator but the isolator only adds one small change. I will explain both installs for the sake of correctness.

These instructions cover model years 2000, 2001, and 2002 second gen 24V's. 98 and 99's have different fuel filter housings and the install is a bit different (see my next post for instructions on the eariler 24V's).

On the later second gens, the best place to sample fuel pressure is downsteam of the fuel filter (this will also show you when your fuel filter is getting plugged). That means that you need to buy a 24V tapped banjo bolt (or tap your current banjo bolt 1/8" NPT). You then need a needle valve and some line to run to the guage (I think the best thing to use is 1/8" DOT approved air brake line with some 1/4" tubing slid over it for abrasion resistance). The pics will help you understand better. Your setup should look something like this and shows the tapped banjo bolt:



Needle valve installed on bottom of fuel filter housing - using an aftermarket tapped banjo bolt (stock banjo bolt was removed):



The line obviously goes to through the hole in the firewall and to the guage mounted in the cab (there is already a big hole in the firewall - no need to drill or cut one).


Install tips - to install on the bottom of the fuel filter housing remove the two bolts that hold the housing on the engine and pull the housing out...install everything on your bench and reinstall the whole assembly. Also, before firing the truck up....close the needle valve all the way, start the truck and very slowly open the needle valve so that you get a smooth reading. The valve should be open a very small amount (just cracked), and also, make sure the guage goes to zero when the truck is shut off.



*************************
ALTERNATE SETUP (on the VP-44 test port):

You can also use the tapped banjo bolt on the test port on the VP-44 (Injector pump). You will have to remove the 1/8" schraeder valve if you go this route. Personally, I dont recommend this because it ties up your test port, but it is another option:





ISOLATOR INSTALL:

If you want to install an isolator. Isolators tend to be unreliable and diesel eats the diaphrams in some of the isolators which lets fuel into the cab anyway.

But, if you still want an isolator, you will want to ditch the needle valve...and run your line from your sample point (either one that I previously showed), to the isolator sender (which is probably munted on the fender or somewhere else convient). Then a line runs from the isolator, through the grommet in the firewall and to your guage. Between the isolator and guage you have to use antifreeze in the line. Sorry, I dont have any pics on this.

ELECTRIC GUAGES

Again, the install would be pretty much the same....but instead of the isolator, your fuel line would go to the sender and instead of having line with liquid running through the firewall to the guage, youd have a wire.


That being said, fuel in the cab is no big deal. If you use quality parts and do a proper install, you will never have a problem. Both isolators/electric senders can cause reading problems. In which case you will want to verify the reding with a mechanical guage.

Heres a pic of a guage mounted in the cab...



This is the easiest place to mount it but you can also put it in a pillar pod.

I think that will cover just about everything.


Now that you have a FP gauge installed, its time to start looking at upgrading the fuel system. The place to start is moving the stock lift pump (or a better one) to the frame rail and getting a big line kit.

** Pics are courtesy of the guys at DTR **

 

Update,

For 98 & 99 Models years (and possibly some 2000's as well):

As you can see in the pics, the sample point is at the top of the fuel filter housing and its the forward most plug:



And this pic shows a guage with an electric sender:



Again, the great pics are from the guys at DTR

 

FYI, this is from the 24V Cummins repair manual:

 

Glad i found this thread. lots of good info on it. i just hooked up my mechanical fuel pressure gauge and have been having nothing but trouble with it. well let me correct myself it worked for about a day or two now it takes about 10 to 15 minutes on the road for the gauge to get up to pressure then if you shut the truck off and go back to in even a half hour later the gauge will still be reading 13psi with the truck off (still reading the preasure that my truck had when i shut it down) I think i'm going to try to fill it with anti freeze and water one more time then go to the tapped banjo and needle valve method.. Good job on this one Dr.

 

Cameron.......sounds like to me you have a needle valve that is just barley cracked open????

 

what do you mean? do you think i should can the isolator and go with the needle valve

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