Rebuild my Cartech/B.E.G.I. 2025 FMU for maintenance reasons. I purchased the rebuild kit through Hahn Racecraft, but I believe it is the exact same kit available here on Bell's website. I decided to put this tutorial together because I was not able to find information myself anywhere else on the web.
http://www.bellengineering.net/index.php?cPath=7
For those of you who don't know, Cartech and Bell Engineering sell essentially the same product under the same model number. It is a rising rate FMU with adjustable idle/base fuel pressure with a needle valve which controls the onset of fuel pressure gain under boost. Both parties accuse the other of ripping off each others design, and claim the competitors product is inferior. I don't know what the truth is but just be aware there are slight varies between some of these units.
Here is what is included in the kit.
1) One large gasket/diaphram
2) Two lower gaskets
3) One Spring
4) One Needle Valve
5) Several stainless steel shims
Optional
6) My kit also included the washer which seats on top the spring for the top half of the unit. It also included an extra brass barb for the boost reference line.
Stage 1 (Disassemble)
Disassemble the entire until. Make notes of the order in which things come apart if needed.
Four bolts on the bottom of the restrictor block will release the top half of the unit. You can leave your fuel return lines hooked up to the restrictor block to make things easier. Be sure to clean any old sealant off the top of the re stricter block. Once you pull off the top half along with the lower gasket and shims which go under it you should see this.
Now that you have the top half off there are 4 bolts on the top half of the unit which you need to remove with an alan wrench. Once these 4 bolts are out you can split the unit and expose the larger diaphragm/gasket. You will also see that the diaphragm assembly has a bolt with a washer on the top side. (the spring seats on the washer) On the bottom side of the diaphragm you will see a larger washer, the bolt goes through the diaphragm and larger washer and screws into a cylindrical metal plunger. This plunger goes through the bottom half of the upper unit to exert pressure on the lower gasket and shims.
You can now remove the idle/base fuel pressure set screw (be sure not to misplace the sealing washer which goes under the set bolt) You may also need to replace this sealing washer. They are available on Bells website. You can remove the needle valve and boost refrence line barb from the upper billet half with a socket.
Stage 2 (Clean and refinish parts)
Once you have everything apart now is a good time to take the billet pieces and polish them up.
Make sure you also clean off any old sealant around where the gaskets seat.
I noticed that on my plunger there was some scoring. This was preventing the unit from operating smoothly. Be sure to inspect yours. If the scoring is bad enough I suggest ordering a replacement.
Mine was not to bad so I was able to polish it out on a drill press with some emery cloth.
Once you have inspected the plunger make sure it does not bind in the lower half of the top piece of the unit. There was some scoring inside mine so I decide to clean it out a little. Take a piece of emery cloth, roll it up and oil it. Once its inside the cylinder it should expand to where you can spin the whole piece and lightly buff out side of any burrs. Be sure you are using very light emery cloth, you do not want to ream out this hole any more than necessary or you my ruin the whole piece.
*Note I cut the polishing cloth long enough I could hold it in my hand to spin it so it was polished out evenly.
Stage 3 (Re-Assembly)
Once everything is cleaned up now its time to get out the new parts and re-assemble.
Here we have washer prepped with sealant which goes on top of the upper large diaphragm.
Be sure to use a minimal amount of sealant.
I placed some sealant on the bottom head of the bolt to prevent pressure from working its way down through the center shalft and decreasing effectiveness of the diaphragm.
*Note the marks on the top of the washer, you can see where the spring has seated itself in the past.
Next the plunger goes on over the larger washer on the bottom side with a bit of sealant in the threads.
Everything goes back together like so.
Now its time to put sealant on the two pieces where they will mate to the outer portion of the diaphragm/larger seal gasket.
Insert the seat washer into the top billet half, and then grease the spring and insert it into the top half. It helps if you back the base/idle fuel pressure set screw out all the way.
I put a small bit of grease on the plunger to prevent it from binding. You may also use anti-seize as it may hold up better than standard grease.
Hold the top half upside down after inserting the diaphragm assembly into the bottom billet half. Sandwich them back together.
Tighten down all the top screws. Use some thread sealant on them. Remember to slowly tighten them in a clockwise motion.
Now its time to prep the lower restrictor block assembly. Take a shim and neatly cut the corners off to make it easier to seal up on re-assembly.
I used a fuel proof sealant where the lower gasket would be mating.
Place the lower gasket on top of the shims.
Now its time to seat the upper portion of the unit back onto the restrictor block.
Put the screws back in the bottom side and tighten everything down. Re-insert the new needle valve and hose barbs.
I recommend giving it time to allow all the sealant to dry before re-pressurizing the system.
Hope this has helped!
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