Facet Duralift not enough pump to keep up?

On my 91 I have a Moose Jr and the regular basics most have here. It is kept in good mechanical condition. I built an electric fuel system for it a while back a did a job that is damn near factory quality. It has a relayed power supply, inertia switch, all Parker pushlock fittings.
I installed the Facet pump just in front of the fuel selector valve. It always maintains positive fuel pressure but drops down to 2 psi on a hard pull. 6 psi max pump on, engine off. about 4 psi normal driving.

I did the following tests to be sure it wasn't something else:
Tanks have recent new shower heads and debris removed. Just to be sure I teed a vacuum gauge in at the pump inlet. No vacuum present at pump inlet under load. Screen on pump clean, fuel filter fresh.
With an open line the pump takes 38 seconds to fill a pint bottle. Seems to be a full stream.
Temporarily blocking the air bleed line off the top of the fuel filter head improves fuel psi about 1 psi. Temporarily blocking the bleed line off the top of the pump has no effect on the psi. There is very little voltage drop to the pump.

Has anyone else had problems with the Facet Duralift keeping up with a strong running 7.3?

I hate to have to do the system over but I'm thinking I'll have to have 2 Duralifts in parallel or a Holley Red. Not sure I can fit a second Duralift on a reg cab 4x4, I have it tucked up tight between the back of the transfer case and the front of the fuel tank so brush and rocks don't take it out. If I do a Holley Red it will have to have a filter on the suction side to keep big stuff out.

Thoughts?

Iirc, that's fairly normal-ish.

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I installed the Facet pump just in front of the fuel selector valve. It always maintains positive fuel pressure but drops down to 2 psi on a hard pull. 6 psi max pump on, engine off. about 4 psi normal driving.

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As long as you have pressure to the IP, your good to go.

Why do you think you need more?

Your Vacuum switch on the filter will let you know when you don't have enough.

Garbage_Mechan said:

I have it tucked up tight between the back of the transfer case and the front of the fuel tank so brush and rocks don't take it out.
Thoughts?

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your not taking advantage of one of the superior pro's this pump offers; the ability to draw fuel up 10'. you can mount it up in the engine bay where it can easily be serviced and out of harms way.

Have you seen this video?

https://www.youtube.com/watch?v=3nQEwKIZQKs

Compares the 40285 VS 40222, Its not a scientific test per say, but does show a visual difference

40285 4-7 PSI @ 33 GPH

40222 9-11.5 PSI @ 33 GPH

Stats according to Facets site
http://www.facet-purolator.com/dura-lift-pumps.php

11psi through 1/8" is 64gph
4psi through 1/8" is 39gph
2psi through 1/8" is 27gph

Thats free flow pressure differential

OLDBULL8 said:

As long as you have pressure to the IP, your good to go.

Why do you think you need more?

Your Vacuum switch on the filter will let you know when you don't have enough.

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Was it a pump inside the injection pump that it uses for the advance mechanism or was it inlet pressure to the injection pump? I was thinking fuel pressure was pretty important to the injection pump?

franklin2 said:

Was it a pump inside the injection pump that it uses for the advance mechanism or was it inlet pressure to the injection pump? I was thinking fuel pressure was pretty important to the injection pump?

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I don't know why your asking that question. Two (2) PSI to the inlet of the IP is enough to supply fuel to the IP. The OP says he has enough fuel even on a hard pull.

But to answer your question, if I can. If you read Mel Agnems IP pressure test, you would understand it.

Yes, a higher fuel inlet pressure up to 5 PSI does effect the advance somewhat. But nobody should be concerned with that. Millions of these diesels run on a mechanical lift pump that supply about 2 PSI at the IP. The mechanical Advance is controlled by the throttle position, a cam on the end of the throttle shaft operates the mechanical Advance.

Oye vey

Whoa, didn't mean to ignite such passion. The fact is Mel is the one who indicated he thought my fuel pressure is lower than optimal, thus robbing dynamic timing. He also indicated he runs a Holley Red for this exact reason. My apologies to Mel for dragging his name into this discussion, however when the man who has done the most development work and actual measurement of the dynamic operation of these pumps gives me something as a fact, I'm going with it. The word was 2 psi is fine from the standpoint of causing pump issues or failures but not optimum for performance. I'm getting attacked here for requesting some information, I wasn't trying to impress my opinion on anyone.
As to a couple points of discussion. I did not mount the pump under the hood because of three reasons, 2 of which are just my preference: Don't want clutter under the hood. Not that there is a documented problem, however why expose the pump to under hood heat. The actual performance related issue is that while proven capable of pulling fuel 10ft, fluid dynamics are that nearly any pump is more efficient pushing than pulling. Remember that I'm that guy that always wants not just good enough but the optimal.
We need to remember these Facet pumps were made for reliable operation on a small displacement 4 cyl engine on a ******. We are running a 444 cu in turbocharged engine at about 250 hp. Does anyone think it is strange we are feeding that through a 1/8th pipe thread fitting with likely a 3/16 id?
BTW, I don't just fool around with these old trucks (which I'm a big fan of because of reliability and simplicity) I have been working on diesel equipment since 1978. Ever wonder how the fuel in a Cat scraper gets from the fuel tank in the rear 20' foreword to the engine? Can I please go back to gathering info? Perhaps we will come up with the next optimization of the IDI platform.

Forgot to mention I have built several IDI fuel systems before this one. The most impressive one used a Walbro GLS series pump similar to what s Powerstroke uses but at a lower pressure. Still too high for our pump so a fuel regulator was used. Worked well, noticeable performance increase, just too finicky about loosing prime and purging air. Might do a redesign of that one. Fuel pressure would run steady at where the the regulator was set. Got interesting if it was set over 8 psi. Needed to figure out an air bleed system so loosing prime isn't an issue. I had that system on the 86, nice to get away with using company resources and my fleet mechanics to do fab work. Those days are gone now. In the end I went to the Duralift on the 86 (optimized non turbo) because the Walbro vibrator pump had the same PSI results as the Duralift ended up Same situation as the 91 I started this discussion with. Non turbo 6.9 would draw down to barely 2psi.

Lastly, this really started with me discussing pump diagnostics with Mel. On the 91, I had a bad injection pump that was drawing the Duralift into a vacuum. Don't know why yet, but changing the injector pump brought fuel psi back into the norm.

I have a very similar fuel system to you. Moose Jr., facet on the frame just after the selector Valve, etc...

Under full throttle, my fuel filter light will come on. I have contemplated a fuel pump Change, just haven't done the research to what I want to go with or how....

I have a bull moose and misters and have no fuel issues. I don't have the factory filter setup but I've never noticed any loss of power running the cat filter and pump setup. I wasn't a fan of reducing the fuel supply to 1/8" npt no matter how many people said it worked for them. I run jic 5 fittings and stainless line from my fuel pump setup.

http://www.ebay.com/itm/302020540180

To Garbage_Mechan

Whoa, didn't mean to ignite such passion.

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What I wrote above, was addressing the question of what franklin2 asked. In no way was I referring to you. Sorry if you took it that way.