Needless to say, many have found the OEM fuel pump on the 950’s to be sorely lacking in durability. The pump pumps fine, but the internal control circuit is the weak point. Points, that is, are the problem. The Mitsubishi fuel pump that KTM uses is a diaphragm type with a mechanical interrupt mechanism. This mechanical interrupt is what causes the pump to cycle through its stroke. It is the points that make and break the power connection each time the pump goes through a stroke (several times a second) that erode and eventually fail. Below is a photo of the points in an OEM pump after 20k miles.
And with the points opened. You can see that there is a bit of material transfer. This is normal for contact points that are interrupting DC current to an inductor. In ignition distributor breaker systems there is a capacitor wired across the points that extends the life of the points, but they eventually wear out and are normally replaced every 20k miles, or so. One of our OC members, ABYSS, has found the manufacturer of the Mitsubishi points, but they are not cheap and they don’t sell to individuals. But here’s ABYSS’ info anyway:
“MFG K&L Supply is the MFG they have 82 in stock they do not sell to the public but will work with most motorcycle dealerships. Give them your local motorcycle dealership info and they will see what they can do. The est cost is $36.00 US a set . They are called FUEL PUMP POINT SWITCH KIT
There are currently several projects going on within the Orange Crush community in an attempt to fix this problem on an otherwise very reliable bike. One of the first “fixes” was first proposed and implemented by Pointman0853. He installed a Facet 40105 electronic fuel pump in place of the OEM pump. The good news was that there are no mechanical parts in the facet pump to wear out. The bad news is that the 40105 supplied a higher pressure to the carbs and many folks were having flooding problems. Sometimes the engine would flood under certain conditions while the bike was parked, resulting in a hydro locked engine.
After a little research, I found another Facet pump that spec’d closer to the OEM pump and had check valves to prevent fuel from flowing in either direction when the pump was off. The 40171 has all of the advantages of the 40105 without the flooding disadvantage. One “characteristic” that results from the check valves is that fuel cannot be pushed through the pump in the odd chance it fails. This seemed like a non-issue to me as these pumps shouldn’t fail, and if it did, it would be a simple matter to bypass the pump or replace it with another “cube type” pump found in almost any auto parts store in the world just to get home. Facet pumps are used extensively in the experimental aircraft community and have an excellent reputation for reliability and customer service/needs.
The 40171 draws 740 ma when running. The OEM pump draws 1000 ma, so all of the bikes original power circuit wiring and the pump relay should work fine for this application.
With all that out of the way, it’s time to get dirty. First remove the two bolts holding the front of the skidplate with a 10 mm socket. 3/8″ inch drive is best here as the bolts are “loctite’d”, and let it hinge down as shown. Also, it is easier to access the fuel line with the voltage rectifier/regulator (VRR) dismounted. Two bolts with an 8mm socket.
This is what the OEM pump looks like mounted in its stock position to the bottom of the battery box. The clear hose (red arrow) is a vent for the OEM pump’s contacts. It loops up into the frame. You can remove this. It has no use with the Facet pump.
The OEM pump can be removed fairly easily by prying between the rubber mount and the battery box. Once its removed you will see two flat prongs sticking out from the battery box that engage the OEM rubber mount.
Now snip the wiring to the pump. I left enough wire on the OEM pump so that I can add a connector and use it as a spare (fat chance that’ll ever happen), since its still working well.
Below is a comparison between the OEM Mitsubishi pump (top), and the Facet 40171 (bottom). Install your 1/8″ X 5/16″ barbed fittings with fuel resistant teflon tape (yellow). I used straight fittings rather than the multiple angle fittings some have used. Simple is usually better, as it is in this case. Less joints = less chance for leaks in the future. Besides, this looks better.
Remove the rubber mount from the OEM pump. It’s a bit of a chore to do this because of the raised lip on the pump fits into a recess in the rubber mount, but with a little elbow grease and some silicone spray it can be done. Careful not to jab yourself with a screwdriver while doing this.
I wrapped closed cell neoprene around the input check valve on the 40171 and installed the OEM rubber mount in the position shown below. Also note that the metal mounting tabs on the pump need to be removed or bent out of the way, as shown here. Direction of fuel flow is as the red arrow shows. It is well marked on the pump itself.
The new 40171 now mounts in virtually the same location as the OEM pump. This setup is very secure and clearance is adequate with the OEM skidplate. Since it fits in the same space as the OEM pump, it “should” fit with an aftermarket skidplate, but you should check your own situation.
Note: a fuel filter in the input line to these kind of pumps is MANDATORY, as they are not tolerant to any crud in the fuel. Facet suggests a 74 micron filter. Most automotive filters aren’t marked with their filtering media size, so do as I did and get the best you can find and change it often. I like the clear, so I can visualize the contamination it has removed. This one also has replaceable elements, so I can carry a bunch with me on a trip in the same space as one whole filter takes.
Use high quality fuel line and hose clamps. Protect the fuel lines if they apt to be damaged or kinked. Stainless steel braided fuel line with aircraft fittings is my next project.
Attach the proper female spade connector to the blue-black wire in the original wire harness (the one you cut earlier). Use high quality crimp connectors (this one comes with shrink tubing pre-installed) and a good crimping tool. I used a convenient engine case bolt for the ground lug but you could use the brown wire in the loom if you preferred
Alternate options for connection:
Wire Loom Black/Blue to Facet Red
Wire Loom Brown to Facet Black
You can splice the OEM pump’s connector to the Facet wiring, or a better (more sanitary method) is to pop the spade connectors out of it, and either salvage those to crimp to the Facet wiring or crimp on new. The pins can be pushed out of the plug with a special tool that you buy or make. Click the next image for link to a site that will help you do this. Be sure to pack connector with high temperature dielectric grease (silicone grease) before connecting to the wire harness.
Tidy up your hoses and secure as needed with zip ties. The red arrow points to the OEM fuel line that carries pressurized fuel from the output of the pump to the carburetors. The green arrow points to the new 5’16” fuel line that carries non-pressurized fuel from the left tank shutoff to the inlet of the pump.
Connect the new input fuel line to the shutoff valve, and re-install the VRR. Help your VRR live by spreading some heatsink paste on the mounting bracket to VRR surface first. While you’re down there, check the VRR to Stator connector (the brown one the red arrow points to in the image below). They are subject to corrosion and many times they will melt due to high resistance between the contacts. Disassemble as needed and clean the contacts thoroughly, then pack with high temperature dielectric grease. I check this connector at each oil change.
Re-install the skidplate (be sure to use blue loctite on the threads). Start up the engine and check for leaks. You should now be good for many more trouble free miles.