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Discussion Starter #1 (Edited)
I've been chasing a couple of small issues on my 2001 F-350, and put together a kit to test the fuel pressure. I know we have a few other 7.3 owners here, so I figured I would share the process. You can buy fuel pressure test kits for these trucks, but the ones I found were over $100 and you can assemble one yourself for less than half of that.

Low fuel pressure can cause a number of issues, including low power and early injector failure. If your fuel pressure is less than roughly 35 PSI under load, the injectors do not receive adequate lubrication and can develop issues. Likewise, if pressure into the injectors is too low, you won't be delivering as much fuel into the combustion chamber as you should and the truck will feel weak. Ideally you want to be within 10 PSI of 60 at idle. Anywhere from 50-70 PSI at idle is pretty normal. Under load, which is accelerating, wide open throttle, etc you should see at least 35. If it's low there can be a few different causes, but for now we'll just focus on testing it. The process is the same for the 94-97 PowerStroke trucks, but the fuel bowl fittings will be different. There are a lot of different fitting/ hose combinations that can be used to do what we're doing, this is just what I did for a temporary test setup.

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The fitting that threads into the Super Duty bowl is a #4 O-ring boss. I used a #4 o-ring to #4 JIC adapter, followed by a 90* JIC elbow into a JIC hose barb. I ran 48" of diesel rated fuel line to a 1/8" NPT hose barb, which was threaded onto a 0-100 PSI liquid filled gauge temporarily attached (aka, zip tied :lol:) to the cowl. The fuel system is fairly low pressure at this point, so barb fittings and hose clamps will work. Some folks have installed fuel pressure gauges in the cab as a permanent fixture, but with my stock truck that's unnecessary. If I were doing a permanent install, I would mount the gauge where I wanted it in the cab, then measure and have a custom hose made with crimped ends to go from #4 o-ring to whatever fitting was on the gauge I used. Regardless of how you go from fuel bowl to gauge, this is the basic process.

First, the fuel bowl. This is where your fuel filter is. It might have a stupid black, plastic cover over it with a little hinged lid. Take that dumb thing off and put it on a shelf, all it ever does is get in the way. :laugh::laugh: You should see the fuel filter bowl in the center of the valley, behind the HPOP.

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On the back (firewall side) left of the fuel filter bowl is a yellow lever to drain the bowl. Flip it backwards and drain the bowl. On the back right (driver's side) of the bowl is a plug.

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Remove that plug. It takes a 3/16" allen wrench.

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Install your o-ring fitting here.

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From your o-ring fitting, attach the rest of your hose/ adapters. Don't use thread sealant on o-ring or JIC fittings, do use it on NPT fittings.

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Check for leaks before you close the hood. Make sure the fuel bowl drain is closed, then turn the key on and let the fuel pump run. The pump will shut off in about 30 seconds, and you may have to turn the key off and back on for the bowl to completely refill and pressure to show on the gauge or a leak in your new system to start. Once pressure shows on the gauge, you can start the truck.

I ran my gauge over and attached it to the cowl beside the windshield wiper. If you do this, make sure the wiper doesn't hit the gauge if it starts raining.

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And you're done! My truck is holding a steady 70 PSI at idle which is in the right range, tomorrow I should have the horse trailer hooked up and see what it does under a load.
 

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On my OBS powerstroke I built a electric fuel system with adjustable fuel pressure regulator. It is amazing how these engine have a sweet spot for fuel pressure. Mine sits right at 64 psi and the engine engine responds beautifully. Any higher or lower and it just isn't the same.
 

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Hey Blake,
Are you still running the gauge on this? Still to the outside?

Did you ever think of running it in the cab or was the thought of a fuel leak what made you mount it outside?
 

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Hey Blake,
Are you still running the gauge on this? Still to the outside?

Did you ever think of running it in the cab or was the thought of a fuel leak what made you mount it outside?
For inside the cab monitoring you would want to use an electric gauge or one with an isolator. You do not want to introduce fuel into the cab.
 

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What kind of issues are you having with the truck?
 

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Interesting , all though I've never once needed to test fuel pressure on a 7.3 , usually the LPOP or HPOP systems cause most of the headaches I see aside from electrical


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Discussion Starter #10
What kind of issues are you having with the truck?
Well, it's been a few years so the list is a little longer now. :laugh: The rear axle has an intermittent, unexplainable pinion seal leak. The vent is clear, the seal has been replaced twice and the yoke has had a repair sleeve put on it. There is no discernible set of circumstances that cause the leak, it can leak after 5 miles or it may go 500 perfectly dry. U joints in both front and rear driveshafts are new as well.

The transmission synchros are worn, downshifting is a bit tricky. When you let off the throttle, especially going downhill there's a loud growling that I believe is either clutch or pilot bearing related. The front axle steering u joints are binding, and will intermittently cause the steering to pull in one direction or the other.

The biggest issue I believe is fuel related and I suspect injector cups. The truck has very low power, single digit fuel mileage and smokes light a freight train under light loads. I don't even try it with heavy loads anymore. Intake is in excellent shape, fuel delivery to the rails is good, exhaust is good on both sides of the turbo with new up pipes and gaskets, manifold gaskets, etc.

My patience with this truck has been exhausted. I'm done fixing it. I've been working on it literally from less than an hour after I bought it. Didn't even make it out of the town where the dealer was before I had to stop and fix the wipers. It's been one thing after another and I'm done. Been towed twice, left me on the side of the road 4-5 times that I was able to fix and have had numerous other issues that would have left me stranded if I hadn't caught them in time. Once I get the white truck ironed out in the spring, the F-350 will either be sold or maybe traded in on a Subaru to replace our Baja. I like the Crosstrek, I'm partial to the burnt orange color but the better half can't stand it. We're both okay with the desert tan though, so maybe that. :munch:

If anyone wants a 7.3 F-350, call me around June. I can set you up. :lol:
 

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Well, it's been a few years so the list is a little longer now. :laugh: The rear axle has an intermittent, unexplainable pinion seal leak. The vent is clear, the seal has been replaced twice and the yoke has had a repair sleeve put on it. There is no discernible set of circumstances that cause the leak, it can leak after 5 miles or it may go 500 perfectly dry. U joints in both front and rear driveshafts are new as well.

The transmission synchros are worn, downshifting is a bit tricky. When you let off the throttle, especially going downhill there's a loud growling that I believe is either clutch or pilot bearing related. The front axle steering u joints are binding, and will intermittently cause the steering to pull in one direction or the other.

The biggest issue I believe is fuel related and I suspect injector cups. The truck has very low power, single digit fuel mileage and smokes light a freight train under light loads. I don't even try it with heavy loads anymore. Intake is in excellent shape, fuel delivery to the rails is good, exhaust is good on both sides of the turbo with new up pipes and gaskets, manifold gaskets, etc.

My patience with this truck has been exhausted. I'm done fixing it. I've been working on it literally from less than an hour after I bought it. Didn't even make it out of the town where the dealer was before I had to stop and fix the wipers. It's been one thing after another and I'm done. Been towed twice, left me on the side of the road 4-5 times that I was able to fix and have had numerous other issues that would have left me stranded if I hadn't caught them in time. Once I get the white truck ironed out in the spring, the F-350 will either be sold or maybe traded in on a Subaru to replace our Baja. I like the Crosstrek, I'm partial to the burnt orange color but the better half can't stand it. We're both okay with the desert tan though, so maybe that. :munch:

If anyone wants a 7.3 F-350, call me around June. I can set you up. :lol:
I'll take it off your hands if you are willing to give it away.
In the meantime check with the peeps at Powerstrokehelp.com They should be able to point you in the right direction. If I had PS problems this would be the first place I called.
He also has a ton of videos posted on YouTube covering most of the common problems.
 

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Discussion Starter #12
I'll take it off your hands if you are willing to give it away.
In the meantime check with the peeps at Powerstrokehelp.com They should be able to point you in the right direction. If I had PS problems this would be the first place I called.
It won't be free, but it'll be a deal. I'm tired of screwing with it.

I've been on all the PSD sites over the years, built a few pulling and race trucks but got away from it a while ago. Don't miss it, but the fact that I ate, slept and breathed the damn things for so long has left me in a position that even though I don't want to work on it, I feel like I have to.
 

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I'll take it off your hands if you are willing to give it away.
In the meantime check with the peeps at Powerstrokehelp.com They should be able to point you in the right direction. If I had PS problems this would be the first place I called.
He also has a ton of videos posted on YouTube covering most of the common problems.
I'd stay away from p0wer$trokehelp.c0m. He claims the only issues with the 6 oh no is the coolant cap would fail causing the head gaskets to blow. Go to a forum like powerstrokearmy.com, much better place to get info
 

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I see you have done a lot your self and that's the best way to learn but there is a lot to check before you dump 1200 per bank in injectors, fuel pressure isn't likely but possible, a lot more involved than I could explain here and I'm no expert I avoid these at as much as possible and wouldn't own on personally if it were free, but sounds like no power with smoke your having a wastegate issue or no boost or even a Boost leak from the turbo have you spent any time with the wastegate its no fun to get to

Any boost or exhaust leak will kill the power on your 7.3


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Discussion Starter #15
I see you have done a lot your self and that's the best way to learn but there is a lot to check before you dump 1200 per bank in injectors, fuel pressure isn't likely but possible, a lot more involved than I could explain here and I'm no expert I avoid these at as much as possible and wouldn't own on personally if it were free, but sounds like no power with smoke your having a wastegate issue or no boost or even a Boost leak from the turbo have you spent any time with the wastegate its no fun to get to

Any boost or exhaust leak will kill the power on your 7.3


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Been through the intake system, boost is good, etc. At this point the two possibilities I have left are low compression or injectors hanging open/ cup seals leaking fuel into the cylinders. This truck has cracked an injector nozzle twice (different cylinders), and I'm not pulling them again. Through detailed troubleshooting and the process of elimination I've narrowed the problem down to one of two things, both of which will be more work than I'm up for right now.
 

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Been through the intake system, boost is good, etc. At this point the two possibilities I have left are low compression or injectors hanging open/ cup seals leaking fuel into the cylinders. This truck has cracked an injector nozzle twice (different cylinders), and I'm not pulling them again. Through detailed troubleshooting and the process of elimination I've narrowed the problem down to one of two things, both of which will be more work than I'm up for right now.
I would bet you could find a young energetic 7.3 enthusiast who would love to dig in to that engine. He hasn't busted his nuts doing things like that a hundred times yet... Should sell pretty good for you I would think.
 

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Been through the intake system, boost is good, etc. At this point the two possibilities I have left are low compression or injectors hanging open/ cup seals leaking fuel into the cylinders. This truck has cracked an injector nozzle twice (different cylinders), and I'm not pulling them again. Through detailed troubleshooting and the process of elimination I've narrowed the problem down to one of two things, both of which will be more work than I'm up for right now.
Yeah compression and leak down would be my next go to also , I understand you not wanting to pull injectors nothing about this engine is easy and the 6L or IHC VERSION vt365 is a complete nightmare

Maybe contact your local trade school diesel program and donate the truck for a semester for the instructor to use as a drivability diagnoses tool you would still have to buy the parts but as long as the instructor isn't a tool him self (and there is a risk) you should get some results


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Am I the only one that doesn't find the 7.3 that difficult to work on? There is plenty of room around the engine, you can get at most everything (up pipes being the least accessable) and the wiring is straight forward. I've worked on well kept low mileage 7.3s as well as high mileage ratty 7.3s, not one yet has stumped me.

Not saying this is the case here, but usually what I run into is the owner not wanting to spend the money to do the repair correctly.
 

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I owned a couple of 7.3's in 2000 & 2002 Excursions. Also owned a couple of 6.0's in 2004 & 2005 Excursions. Would much rather work around a 7.3 than the 6.0. That being said I was lucky. Other than having to replace a crank sensor on the 2000 Ex and an EGR cooler (upgrade) and turbo clean-up on the '05 Ex I had pretty good luck over about 600,000 miles. Unfortunately the '04 gave it's life up fairly early in a 13 car pile up. The rest all went over 200,000 miles each with mostly just routine maintenance. Don't miss driving ~75-80K a year at all.
 

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Am I the only one that doesn't find the 7.3 that difficult to work on? There is plenty of room around the engine, you can get at most everything (up pipes being the least accessable) and the wiring is straight forward. I've worked on well kept low mileage 7.3s as well as high mileage ratty 7.3s, not one yet has stumped me.

Not saying this is the case here, but usually what I run into is the owner not wanting to spend the money to do the repair correctly.
I think it's a matter of cost of repair vs longevity of the vehicle, at least it was that way in my case when I started doing my own work. I spent $2k on my most recent repairs/upgrades which is way less than what I'd be spending to get a newer truck.


Maybe I shouldn't have brought this back up...
 
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