Fuel pressure

[a5150nut]

John,

Where is the best location to monitor fuel pressure on a 2006 DMax fuel rail or line going to pump?

I have a 2 micron pre filter back at the tank and was thinking of adding a fuel pump there also.

And what are the expected readings for both locations?

[DmaxMaverick]

If John's doing it right, he's taken the day off. So, I'll jump in.

(Caution)
The "rail" is subject to near 30,000 PSI. You'll need a special gage and hardware for that. Probably not something you'll do. If you want to know the rail pressure, use a scanner (the PCM reports it).

The remainder of the OEM system (between the high pressure pump and tank) is 100% suction. No "pressure" to monitor, only vacuum. It is beneficial to monitor it, though, as it will indicated the health of the filter(s).

If you add a lift pump near the tank, similar to the 6.5L, this changes the system. I recommend installing a gage between the "last" filter and high pressure pump. This will also allow you to monitor filter health, to some degree. It depends much on the grade of pump you will be using. High volume, low pressure is recommended. Any pressure above zero PSI is beneficial, in that prevention of any vacuum is the goal. 4-8 PSI is a good range. If the pump flow is sufficient, it will keep up under full load, even if the pressure drops to near zero. Take into account a filter that's "used up" will reduce that.

Have a look at John's website, specifically the fuel pressure gage tool. It describes what you may see, and what adding his pump(s) will do for the system. I have the gage, and it's very handy.

[a5150nut]

Thanks DMax. That is more of what I had in mind. I have a CAT fuel filter mounted just in front of the left wheel on what looks like a shop made bracket. It has a vertical plate on the cab side of the filter and would make a nice home for one of Johns pumps.

Filter is already plumed in so all I need to do is determine tank side of line and add the pump and a gauge up front.

Tried to scour the web to see if this filter mount was a kit the PO had used but all I see now is adaptors to mount a CAT filter in place of OE filter. Now if I still had my Way Back machine and could go back to 2006 when it was put in. . . . .

[AKMark]

I would guess you have this.


http://atptrucks.com/duramax-cat-adapter-and-2-micron-cat-filter.html


I know a few folks running it, and plan to upgrade mine this summer.

[a5150nut]

I would guess you have this.


http://atptrucks.com/duramax-cat-adapter-and-2-micron-cat-filter.html


I know a few folks running it, and plan to upgrade mine this summer.

No, I have a pre filter mounted behind the cab to the bottom of the bed rails.
http://www.thedieselpageforums.com/tdpforum/album.php?albumid=37

I have found the one your talking about along with a few knock offs. This looks shop built. Laser cut, crisp bends, well fit.

[AKMark]

Wow, that's different, but probably does a great job.

[Kennedy]

John,

Where is the best location to monitor fuel pressure on a 2006 DMax fuel rail or line going to pump?

I have a 2 micron pre filter back at the tank and was thinking of adding a fuel pump there also.

And what are the expected readings for both locations?

Sorry it's going to take me a bit to remember this forum is here.

I don't actively monitor fuel system restriction/pressure. Instead I have a gauge that I use as a tool to check periodically.

http://www.kennedydiesel.com/images/Dmax-fuel-filter-rest1.gif


I won't get caught up in all the 2 micron over rating BS, but I will say that I do not care to have the best filter first in line and also don't care to have to do a quick filter change on the road as it means wearing diesel.

[Kennedy]

Quote from my site:

Restriction can be checked at idle speeds and at 2-3,000 RPM. Typically we will see approximately 2-3"hg at idle with very little variance as RPM increases. As a filter loads up, you will see restriction increase. When you hit about 5-6" hg (2" above baseline) I consider the filter well used and due for replacement. The early Dmax single layer media filters would run a long time without much of an increase in restriction. The latest dual media units seem to be doing a much better job of collecting dirt, but start at a higher restriction that rises quickly as they load up. Having this gauge on hand allows you to quickly and easily verify the condition and can be very beneficial when diagnosing fuel system related drivability issues. Typical OE filter life is < 15,000 miles. We have seen these filters load as early as 2500 miles or less depending on fuel quality.

[a5150nut]

Sorry it's going to take me a bit to remember this forum is here.

I don't actively monitor fuel system restriction/pressure. Instead I have a gauge that I use as a tool to check periodically.



I won't get caught up in all the 2 micron over rating BS, but I will say that I do not care to have the best filter first in line and also don't care to have to do a quick filter change on the road as it means wearing diesel.

That's alright John, change takes time.

And I agree primary should be a rock filter, secondary a little finer. But that is the way the truck came. I am considering one of your pumps between the tank and primary filter. 1/2 in line is already there just need the pump and two fittings and drill the bracket to mount the pump to it. I already have a Donaldson 4 mic to replace the stock filter.

I was just trying to find some sort of fuel pressure guage to monitor filter life. If nothing else a <1lb murphy switch and an idiot lite.

[Kennedy]

I prefer to shut the pump(s) down and go by restriction as it's more precise. Otherwise any gauge any place just keep the scale small.

The OE filter is 4 micron these days. Not sure about the WIX plastic garbage, but a true OE spec multi layer element would be.

[Kennedy]

No, I have a pre filter mounted behind the cab to the bottom of the bed rails.
http://www.thedieselpageforums.com/tdpforum/album.php?albumid=37

I have found the one your talking about along with a few knock offs. This looks shop built. Laser cut, crisp bends, well fit.



What you have there is a $@#^tane setup. Built by the joker that started the diesel place in a revolt crying oppression and suppression of his free speech rights here. He even went so far as to accept donations to cover operating expenses in the beginning only to later sell the site to Auto Forums for a healthy sum.


At any rate it looks like you have one of the early bare metal die cast units. If it was never in salt/corrosive environment you should be OK, but many of those crumbled and fell off in service.