7.3 PSD Fuel Mod by William

The 94-97 7.3 Power Stroke Diesels are equipped with a mechanical fuel pump and somewhat archaic fuel regulation system. It works good, but when you have things involving springs, they sometimes tend to get weak with age. There is a fix for this, lets go over it.

 

This is probably the cheapest modification you can do to your truck. It’s simple and effective.

First we need to start the truck up and let it idle down into a normal idle to measure the fuel pressure off the fuel bowl. These trucks are equipped with a Schrader valve for doing this. Grab an old stick style tire gauge you wont mind destroying and take the cap off the Schrader valve. Throw on some eye protection for this as well, fuel might come out the end of your gauge.

Hold it on their tight and get a reading. Double check your readings just in case.

If your in the 55-70PSI range, this modification is not necessary. If you still want to continue if your in the 50-60PSI range, it can still be beneficial depending on how weak your spring is.

Shut the truck off and get the tools out. We will need a 3/4 inch socket and a wrench to turn it. As well, we will need a magnet to pull the pieces out.

For quality of photo purposes from this point on, it will be demonstrated with the Fuel Bowl out of the truck. You do not have to take the fuel bowl out to do this mod, but I had mine out to clean it, so I took some pictures to demonstrate further.

 

 

The big brass nut on the right side of the fuel bowl is what we are after. Make sure you have the socket seated on it properly, because we don’t want to strip this out.

Break the nut loose and unscrew it the rest of the way by hand. There is a spring behind here, we don’t want it jumping out on us and having problems with ordering a new spring, because that can be kinda difficult.

 

 

Behind the brass nut there is a spring. Use a magnet to pull the spring out and hopefully the collar the spring fits in will come out with it as well. If it does not. Use the magnet to pull that out as well. Just a note here, be sure your magnet is clean. We don’t want that stuff sticking to the fuel pressure regulator parts and making it into your injectors.

Here you can see the parts that regulate the fuel pressure. Just a spring and this collar the spring fits in.

Now, we need a metal BB. They are really easy to obtain from that neighbor kid who keeps shooting your privacy fence up. Just go over there and give him a noogie. Then take some of his BB’s and run home.

 

 

Alright, this is our shim for the spring. We insert the BB into the collar, and then we insert the spring in after it.

We then carefully insert the assembly back into the Regulator on the fuel bowl. No picture here, to hard to hold camera and insert the parts in at the same time. Here is a picture of what it looks like inside though.

Carefully note the Nipple on the end of the Brass nut. (Yes, I used the same picture twice.) It is critical that you get this lined up with the spring. If the assembly is in correctly, this should be easy.

Replace the brass nut squarely with the regulator, and turn backwards till the threads line up, then finger tighten the nut back into place. Throw the wrench back on and snug it up good. No need to He-Man it back tight.

 

 

Now deal with the neighbor kids dad and explain to him why you took his kids BB’s and gave him a Noogie and how he shoots up your privacy fence. Drink a beer and watch the kid get a whoopin from his dad.

Alright, now that drama is all over and everything is back together, let’s start the truck back up and check for our new fuel pressure. Same way as before. Note, if you did not clean your Tire Gauge out, I find it pretty easy to clean it out by checking your tire pressure on your truck. Not sure if fuel in the gauge will effect readings any. But we are double checking anyways when measuring fuel pressure so, whatever.

If you are in the 60-70PSI range, your doing really good. Slightly over 70PSI is alright, but too much fuel pressure is bad. I would not suggest leaving the mod in if its over 75PSI. 65PSI is about optimum for our trucks. If you want to find other things to fit in there to shim it differently, go right ahead, just remember what materials your using and if they will get stuck in that collar. You don’t want that.

Close the hood and have fun with the cheapest mod you can do to your Mid 90’s PowerStroke Diesel!

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Dual Mass Flywheels For Dummies by William

Should start out with this having no affiliation with the for dummies series, but when it comes to these things, we all seem to be a bunch of dummies. I’d like to state that I do not 100% know what is going on in this design of failure, so this will mostly be speculation on my part, or for anyone who helps with information or idea’s on what is why or how.

This is the dual mass flywheel. Pardon my rust, but that’s what metal does.  The dual mass flywheel is supposedly two flywheels mated together with some springs as you can see in the picture on the right. Let’s dig inside and see how this thing really works.

Lets get these bolts loose on the top here first, they are the most obvious piece to the puzzle. Almost everything else appears to be rivets except for the two allen screws on the bottom of the DMF. I had to use the impact to bust these things loose, and boy were they on their tight. I do not really think you would want it coming apart.

 

This is the bottom side of the surface that I just unbolted. You can see that it is balanced before assembly. This is the main piece of the clutch that mates up with the clutch surface. The odd thing that I noticed is that the center ring there is very shiny.

 

 

On the center ring here where that shiny surface mated, it was a weird texture. Reminded me of a brake pad or a clutch style material. Lets take a closer look.

 

 

 

I used a screw driver and a hammer to try and chip the surface away. Best I can tell is that this is some sort of clutch style material. This was surely an interesting find.

in these two pictures we can see one of the main reasons of failure in the DMF. You can see these little pieces of what look like metal inside there. I believe they are the main cause of the flywheel becoming unbalanced. They just float around there with no place to go.

This is a picture of the the part that is between the springs. This whole ring is held down with some rivets in one large piece, you can see one of the hold down rivets at the top of the picture.

 

 

I decided to drill the rivets out and press on. After finding the right size and spending a good hour drilling these things out I made some progress.

I used a screw driver and a hammer and had to work my way around the ring to get it popped free. even with the rivets drilled out, it still came off pretty tough. The picture on the right shows the reverse side of the ring.

I set the ring on top of the other piece to show how it would look with the mating surface on the flywheel.

 

 

 

 

Here are some pictures of the springs and the setup without the ring on the assembly.

Here you can see the main cause of the problems with the DMF. The whole center of the flywheel moves and allows this slop between the springs.

As you can see here with the spring out, there is 2 bushings that hold the spring in place and are a buffer between the metal. I’m not sure what the material in the center is, but you can see how the end piece broke off on the one bushing, that is what we seen rolling around in the spring earlier.

 

With all the springs out, you can get a better view of the assembly, there are more plates further in it appears, just like this plate we see on the top.

 

 

 

This is the reverse side of that top plate there. I’m not sure what is up with why this looks like this.

 

 

 

 

You can see there are some copper rings in here that are angled to provide some sort of spring action to the pack. I don’t know if they were compressed or not when I drilled the rivets out and removed the top ring. Hard telling.

 

 

Here is a close up of the rubber pieces on the ring that holds the springs in. You can see they wear as well. I want to say the metal by them wears also, but I did no do any measuring to compare them.

The bottom of the ring here you can see there is more of the clutch material like the other ring. So, we got two identical rings with some springs in the middle pressing them out too two identical plates riveted to the the second part of the flywheel with clutch material on the inner ring to prevent slippage or some sort of resistance against pressure on the springs.

 

That leaves us with this center hub here. I used a rubber piece to show you that this is indeed a bearing pack.

On the back side of this part of the flywheel, as I mentioned before, there are two allen screws. They were remarkably easy to take out also.

 

 

 

Flipping the flywheel back over and pulling away the bearing hub you can see more clutch style material on the back of the ring on the bearing and a piece of plastic with notches in it. Wait, what plastic? You can see the hub is keyed to the plastic ring. I do not fully understand what this does.

The piece of clutch material comes off, with tight tolerances. I had to influence it off a bit, but no hammer was required. You can see there are more rings inside that assembly, which I’m guessing the plastic ring keeps in place. The right ring is a copper ring like the other copper rings with an angle to it for some spring action, and the other ring to the left is really flimsy like a piece of tin.

While I was turning the bearing unit, I did not feel any resistance from the clutch materials on any of the pieces. The only resistance in the hub here was from the flywheel making its short rotations causing some grooving in the race and cups inside physically resisting my turning of the hub while I tried to rotate it. It smoothed out some after a few turns, but you could feel the bearing damage inside. You can see the pilot bearing in this picture is rusted really good as well. It looks like this is the main piece of the Flywheel. Its really a three or maybe even a four piece flywheel, not a 2 piece like everyone has though. Everything stems off this piece here which is held in by the 2 allen screws, then all the other parts are clamped down around it by rivets and springs.

I’m going to toss in the remaining break down pictures in bulk here for you to look around on. I tried to keep like parts from the order they came off together in some sort of break out format.

This is the part where I’m going to throw in large amounts of speculation on the post. Most were educated guesses based upon observations so far.

I believe the main failures of these flywheels has to do with the clutches failing inside the unit. The springs at there to snap it back into place after putting torque on the motor, but eventually wear, or get dirty and stop resisting the pressure allowing more free travel in the clutch resulting in worn bushings for the springs. This eventually worsens as time goes on and more miles are put on the clutch, or more stress would be a better explanation allowing them to damage themselves. The clutches do not resist the turning of the flywheel when you have it out of the truck, the main plate feels as though it is free spinning until it touches a spring pack, there was no resistance in mine.

I really do welcome all suggestions or thoughts regarding this and my explanations. Please be detailed in your comments and reference the picture number you are referring too if you are talking about a picture.

Please also remember, I do not really know anything about these devices or their intended performance, only that it is designed to reduce vibrations.

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