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7.3 PSD Fuel Mod by William

fprshim_0046The 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.

fprshim_0009For 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.

fprshim_0008Break 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.



fprshim_0001Behind 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.


fprshim_0004Now, 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.

fprshim_0010Replace 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!


car loans said...

Springs can be tough to replace even with the warranty.

car loans said...

I'll be sure to try this over the weekend, thank you.

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