Never before seen mess

[BrianX128]

So my 7.3 just came back from getting its dmf to smf swap, put my new pedal assembly, just a lot of winter time things that needed addressed. I was having an issue with the truck stumbling off wot 1/50 times and thought my pump may be shot at 80k. Tried the atf trick and while doing this and a new fuel filter I noticed air intrusion and could not figure out where it was coming from.

@Thewespaul had been walking me though some stuff to look at, I had deleted the entire factory supply line from the fsv and replaced it with rubber line and still some air but almost at random. Was going to delete the fsv and try to isolate whether the tank of fsv was to blame [and already ordered a new fsv and 50' of 3/8 and 5/16 diesel hose..... and this morning something unexpected caught my eye. While going to start on things. If I tilted the facet forward it looked like no air but towards the rear bumper there was air... and it looked wet and well the video tells the story..

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So I guess if you have any odd issues with your facet pump whether you mounted it or not yet in my case cause I have so many extra things there I'm fabricating a mount for all 3 and it's not that high on the list, but check your pumps..

I'm taking it off now to see if its cracked or what happened will post that shortly.

 

[franklin2]

When working on the engine, how do you "notice" air intrusion.

You are running all your fuel lines from the rear of the truck to the front with rubber fuel lines? I always have a bad feeling about that. The factory never did it, though they did use the plastic lines.

 

[BrianX128]

When working on the engine, how do you "notice" air intrusion.

You are running all your fuel lines from the rear of the truck to the front with rubber fuel lines? I always have a bad feeling about that. The factory never did it, though they did use the plastic lines.

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Saw bubbles while making sure the new fuel filter wasn't leaking after I put it on

 

[BrianX128]

Well my plastic sight glass thing at the bottom was able to comfortably be turned an entire revolution.

Cant get any air to go in it now nor can I get it to leak. I still think I'm going to order a spare in case anything happens to either of them on both my idis.

Now I have a spare 100' of fuel line and a fuel selector valve but hey doesnt hurt to have stuff. I have only replaced the supply line from the fsv to the facet pump the rest of my fuel system is still stock and looks ok I guess.

 

[subway]

When working on the engine, how do you "notice" air intrusion.

You are running all your fuel lines from the rear of the truck to the front with rubber fuel lines? I always have a bad feeling about that. The factory never did it, though they did use the plastic lines.

i prefer to run steel lines where i can, you just seem to run into issues with rubber over time degrading. rubber lines are really easy to run but can also vibrate down and droop where you dont expect them to if they are not supported well. i have not done it but i know some guys swear by running air lines for fuel lines.

glad you got it fixed!

 

[DrCharles]

I redid all of my plastic lines with a good quality Gates diesel-rated hose. (Left the steel ones alone). Anywhere it needed protection, I added split-loom tubing. Working fine so far.

But you're right that it does need attention to clamping/tying.

 

[catbird7]

Noticed a lot of guys are mounting those facet pumps up front in the engine compartment. My understanding of electric fuel pumps (which is limited), they function best with gravity flow to the pump simply because they're designed to push fuel not "suck it". Possibly the facet pumps are designed differently? Just guessing however I'd think pumps mounted closer to the tank would offer let opportunity for air intrusion because any breach in the fuel line or poor connections or splices between the electric pump and filter head will show a fuel leak rather than air leak getting sucked into the system. It can't suck air beyond the pump because it's pushing fuel. Just another way of looking at it........

 

[DrCharles]

True, but it's a lot easier to service (and protected from water and road debris) when it's on the inner fender. The Facet pumps we use are rated to lift up to 10 ft.

 

[franklin2]

It does seem like the best place for a fuel pump is at a low point where it can be gravity fed. But guess what happens at the low point also? Water. A little water in the fuel and it can gather at the fuel pump and rust it tight if you let the truck sit for a little while. Or it can freeze up there. I suppose that is why most vehicles with electric pumps now have the pump in the tank.

We had a old 89 f350 dump truck with the 7.3 in it, and someone had put one of those little ticking solid state pumps on the pass side fender. Of all the things that broke on that truck, and all the miles of hauling we did with it, we never had any trouble with that little pump.

 

[Macrobb]

We had a old 89 f350 dump truck with the 7.3 in it, and someone had put one of those little ticking solid state pumps on the pass side fender. Of all the things that broke on that truck, and all the miles of hauling we did with it, we never had any trouble with that little pump.

Mainly because if you can keep the system primed, the IP will pull fuel just fine. Those little solid state pumps really can't keep up with an IDI at full throttle, but the IP can pull fuel if it has to... it just screws with timing.

If it still had the mechanical lift pump, even better performance wise - the IP will get good consistent pressure from that, and the solid state pump will just be effectively just priming it.

 

[laserjock]

I had a similar issue. I had the compression nut back off the inlet fitting and it started pumping foam. I carry a spare pump with me when I go on trips. I even connectorized it. Plug and play. And I can transfer fuel with it if need be.

I’ve been debating a fuel pressure gauge. I have also debated running 2 of those in parallel. Put the second pump on a pressure switch or throttle position switch. You could have the redundancy of the second pump because it will run on one even if not at full spec.

One thing I have wondered about is the supply line size. I wonder if 3/8 is big enough on these low pressure fuel systems. Not to mention the selector valve being a restriction. The facet pumps are rated at plenty of flow at free flow pressures.

Random thoughts.

 

[franklin2]

Mainly because if you can keep the system primed, the IP will pull fuel just fine. Those little solid state pumps really can't keep up with an IDI at full throttle, but the IP can pull fuel if it has to... it just screws with timing.

If it still had the mechanical lift pump, even better performance wise - the IP will get good consistent pressure from that, and the solid state pump will just be effectively just priming it.

The solid state pump was the only lift pump it had. It was a NA engine, but had plenty of power, well as much as a NA 7.3 has.

 

[lotzagoodstuff]

I’ve been debating a fuel pressure gauge. I have also debated running 2 of those in parallel. Put the second pump on a pressure switch or throttle position switch. You could have the redundancy of the second pump because it will run on one even if not at full spec.

One thing I have wondered about is the supply line size. I wonder if 3/8 is big enough on these low pressure fuel systems. Not to mention the selector valve being a restriction. The facet pumps are rated at plenty of flow at free flow pressures.

Random thoughts.

More random thoughts:

Just when you think "it's all been discussed": running twin pumps is actually a really good idea for higher demand pump/RPM IDI scenarios. The really pumped up Grand National crowd goes this route quite commonly, and yes the plumbing gets upgraded to get the volume up to the injectors (see pic below).

I know it will most likely get ruled out because they need to be submerged in fuel for cooling, but even some of the single Walbro style pumps put out north of400 LPH at 40 psi (see second link).

Again, you'd have to submerge one, but the Walbro design is plentiful, cheap and durable.

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https://www.realstreetperformance.com/blog/fuel-pump-test-2018-real-street-performance/

 

[laserjock]

A lot of the race car crowd will run dual fuel pumps. The big fuel cars run a two stage. The warm up and do the burnout on one stage. Then turn on the second stage as the come to the line.

 

[Macrobb]

One thing I have wondered about is the supply line size. I wonder if 3/8 is big enough on these low pressure fuel systems. Not to mention the selector valve being a restriction. The facet pumps are rated at plenty of flow at free flow pressures.

A number of months ago, I put a mechanical fuel pressure gauge on my '93, mounted to the cowl so I could see it when driving.
. At the time, it had my RD2-110 IP on it. So, oversized pump etc.
Put the fuel gauge on the output side of the fuel filter. This setup had a stock mechanical lift pump, stock filter etc.

At idle, it was perhaps 4.5 PSI. WOT 3.5. Never dropped below 3.5 PSI no matter what I did.

That right there is why I like the mechanical pumps. If I need to add a 'primer' pump, so be it. But I'm not getting rid of the mechanical pump.