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I bought a 99 Malibu Sportster LX from a wrecked car auction for a good price knowing I needed to replace one of the windows. Unfortunately after getting it on the water both Speedometers and the Tach would not work. All other gauges worked fine. After several different ideas to fix the problem, I narrowed it down to be most likely the MDC causing the problem… and they are $1000 now which was a bit of sticker shock. So I went on the hunt for other solutions. There is the MDC Delete kit from TRD but that came at a hefty price tag of about $1100. At least I knew I would be getting new gauges and GPS speedos to boot. However I was stuck on wanting something a bit cheaper so I DIY’ed it for just over $400. There are a handful of threads about doing a MDC Delete but none that matched my exact scenarios/wiring/etc... I followed a thread from a different forum and took updated notes along the way. Let me know if you have any questions! The gauges I purchased GPS Speedometers - https://www.amazon.com/dp/B017QRHYQC?psc=1&ref=ppx_yo2ov_dt_b_product_details Tach - https://www.amazon.com/dp/B0000AZ68T?psc=1&ref=ppx_yo2ov_dt_b_product_details Oil Pressure - https://www.amazon.com/dp/B000KOVJFG?psc=1&ref=ppx_yo2ov_dt_b_product_details Fuel - https://www.amazon.com/dp/B005HNNOPS?psc=1&ref=ppx_yo2ov_dt_b_product_details Temp - https://www.amazon.com/dp/B0000AZ7ZR?ref=ppx_yo2ov_dt_b_product_details&th=1 Volt - https://www.amazon.com/dp/B000KOVJK6?ref=ppx_yo2ov_dt_b_product_details&th=1 1. Unscrew dash 2. Unplug all wires from the back of gauges 3. Unplug rocker switches 4. Unplug check engine light and hour meter 5. I used pliers to loosen nuts on the back of the gauges then finger loosened them the rest of the way. 6. I then reattached all the mounting brackets to the gauges so they don’t get lost 7. The check engine light fell out of the dash hole. Set that aside for now 8. Remove tape and tubing from larger wiring harness bundle 9. Remove the 5 pin, 18 pin, and speedo connectors from Mdc. Mine had a 1/4” bolt on the 18 pin 10. Remove the mdc (mine had 3 Phillips head screws Mine appears bent/broken… potentially causing the gauge issue I had 11. Pull the mdc harness plugs up into the gauge area 12. Disconnect gauge harness from the boat harness. 13. Remove all tubing 14. Cut off the gauge connectors (I left a little wire incase I needed to use the connectors again… in hindsight this was not necessary and having the longer blue wire would have been a better idea) You will now be left with 2 separate harnesses. One connected to the 5pin mdc connector and 1 connected to the boat harness connector and 18pin MDC connector 15. Cut off the 5 pin and 18 pin harness connectors (this will leave you with a bunch of stand alone wires and a bunch of wires still attached to the 9 pin connector that re-plugs into the boat Note* Once the 5 pin harness connector is cut you will be left with 2 brown wires, a bundle of black, bundle of red/white and a bundle of yellow. 16. Remove yellow wire entirely - this is the signal wire that came from the MDC which is no longer used. 17. Remove brown wires entirely… these were for the left and right speedo adjusters (I don’t need these in my setup anymore with gps speedos) 18.Strip and crimp connectors on each dark blue wire. These will be for the backlights on the gauges. The gauges I purchased require spade connectors. 19. Butt splice the black bundle or wires to the black from the 9 pin connector. I removed a couple feed of wire here… the wiring no longer has to go down to the mdc and then back up again 20. Butt splice the bundle of red/white to the purple from the 9 pin connector. (Again I removed excess) 21. The orange wire is not used. I chose to butt splice and keep the wire incase I need it in the future. Not sure what it’s for 22. I was waiting for my gauges and ring terminals to arrive in the mail so I finished my harness using old tubing and put new tape on. Each bundle is for a single gauge. The bundle on the left is the excess unused wire from the harness (additional positives, negatives, and light wires plus the orange that I don’t know what it’s for) I did this incase I add any other gauges in the future I don’t have to rework the whole harness. Here is what I bundled together Fuel - Red, black, blue, pink Oil pressure - Red, black, blue, light blue Volt - Red, black, blue Temp - Red, black, blue, brown Tach - Red, black, blue, gray Speedo 1 - Red, black, blue Speedo 2 - Red, black, blue Extra - all remaining wires *Note the gps speedos recommend having a power wire straight from the battery (not keyed) but I didn’t have those in my harness so I will be using a small jumper wire to jump keyed power to the signal terminal on the speedos. All this means for me is the speedos will need to reconnect to the satellite everytime I shut down… something I will likely want to fix in the future… also as I write this wondering if the orange wires are for this purpose? I’ll check on that! 23. Install all of the gauges in the panel 24. I missed a few pictures here but I added all of the ring terminals and installed the harness on the gauges. Note I have one gauge that has a bit of a messy splice I needed due to wires being a bit short (problem would have been avoided had I not left extra wires on the connectors I cut off earlier) I just used some random wire… do as I say not as I do! 25. Hook up the wiring harness back to the harness in the boat as well as the check engine light and hour meter 26. Reattach the dash. *Note my speedos read 5MPH while looking for GPS Signal and then return to zero. The picture shows them during that initializing stage. Overall a bit time consuming yet fairly simple task. If I could have found a new 9 pin connector that matched the boat connector I would have built a harness completely from scratch. There was barely enough wire in the harness for the light connectors and some of the signal wires. But it still worked.

Hi everyone, This is my first post, but about to buy an 05 sportster LX as I’m looking for a good barefoot boat. This one is EFI with the upgraded Monsoon 340. I’m hesitant on getting one with an ECM because I’ve heard stories of older boats with ECMs not able to be replaced. had it checked out by a local mechanic and the timing was off (18) and should be ~10 at idle. He seems to think a tune up (plugs, wires, distributor cap) would get it back to proper timing but I’m just paranoid I buy the boat and it’s an ECM issue and I won’t be able to get the part. I don’t think this mechanic is used to working on malibus. Anyone know what ECM the monsoon 340 needs and any opinion on this boat in general? Always wanted an EFI sportster but wondering if I should back out and go for one with a carb instead. thanks in advance!

Does anyone know what kind of metal the painted tower on a 1998 Sportster is made of? I want to strip it and either leave it or repaint it.

Hey guys, another dude asking cooling questions. This is for the stock 5.7 carb motor. Does anyone have the part numbers for the 160 thermostat and all gasket sets required? I have a small leak at the thermostat housing. Secondly I've had this cooling issue for 2 years now and it's time to solve it for good. Temp rises to 160 at normal pace, then bounces around high and back to 160 quickly, almost like it's a ground issue or something. I need to start going through the whole system to find the culprit (assuming it's not the thermostat). I replaced the raw water pump last year, didn't solve it. From what I've read I need to check the temp sensor, all ground wires, and maybe even the circulation pump? I don't know anything about the circ pump. Please help wise ones.

Hey guys. I recently got a head unit and speakers gifted to me. I went to install and, Yay the boat was factory wired....but I can't seem to get the power and ground wires right or it's so old something is wrong in the system. Does anyone have a factory wiring diagram for a 99 ish sportster or was it wild west back then and they just threw it in?

Hey guys, I've got a higher hour sportster I bought last year. Planning to have the carb rebuilt and do a few other things including the distributor cap and wires. Does anyone know if there is an msd distributor for this application or can you recommend another option? Also what aftermarket plug wires are there available?

Hey guys, I recently got a 99 sportster with the 5.7 carb. engine. I was draining the water for winter and the plug on the port side of the block had a lot of metal flakes attached to it. Does the indmar 5.7 310hp engine have an internal water pump as well or is that just passageway deterioration? I have had issues with cooling this first year with the boat but I attributed it to a bad gauge or sensor. The raw water pump and impeller were replaced in the spring. Thoughts?

In a hurry I unplugged the connection to my speedo adjust pitot select on a 2001 Sportster LX. Can anyone send me a pic with the order of the wires to plug it back in please?

Does anyone know the font on the back of the Malibu Flightcrafts?? I have been searching but I can't find an exact match. Looking to get it replaced on my boat! I have attached an image of the desired font below. https://www.ballofspray.com/forum#/discussion/20007/1994-flightcraft

Looking for a cover for my Sportster LX that can withstand the elements here in the midwest until my indoor storage situation can be resolved. Any recommendations on fabrics, manufacturers, # of vents/supports etc. would be greatly appreciated! thanks!

After about 30 min of normal use pulling skiers today, I lost engine power pulling up a skier from a deep water start, unable to properly accelerate. I also noticed a whining / squealing noise coming from the engine compartment. I killed the engine, restarted, and immediately had sputtering and power loss upon acceleration. I was able to limp / idle back to my dock, but did lose full engine power 2 times and need to restart the ignition just to limp my way back. I put fresh fuel in the boat, ran the blower, and tried to run it again. I don’t have working gauges so am unable to see oil pressure or engine temps. the engine continued to sputter, refusing to accelerate, and when trying to, hiccuping while engaging the throttle, often shutting off. In neutral, I was able to rev the engine without any issues. what are some first steps I can take as somebody with a low DIY skill level? I’d love if this was just the plugs, but the whining noise from the engine sounds like it’s likely part of the problem. I believe the engine is The Indmar monsoon 325, Fuel injected. update: when I turn the key to ignition without starting the engine, I hear a similar but shorter squeel from when it’s running. This squeel comes from the rear port side of the engine which makes me think fuel pump ? the engine also loses power quicker now and shuts off after about 15 seconds. I can also no longer rev the engine in neutral / not under load without the engine conking out shortly after.

Hey guys, I recently posted about another issue regarding fuel pressure after my engine suddenly started sputtering and conking out, and loud whine from the pump - can see more in my original thread on it. Narrowed down to fuel issue, changes filters, cleaned screens, and replaced the pump. Finally got pressure back at the rail...and now the engine won’t turn over after making these repairs... I had a marine tech come do a scan to see what it could be as it’s become beyond my level of diagnostic. He seems to think it’s the ECM. Yet it seems so coinciden diéntale my ECM would die (only 380 hours on the boat) right after solving the other problem with fuel delivery. my question is, is there anything that could have been related from the pump issue that’s causing this ? Or did my limp back to my dock after the pump initially started to go cook my engine / overheat the ECM? before replacing the pump, the engine was turning over, yet wouldn’t stay running. Now it won’t turn over at all. Marine tech thinks ECM is blocking the signal to turn over, sending 0 RPM. See link for trying to turn over while scanner is connected. We also changed the ignition module to rule that out as it was a $40 change out vs. A $1200 ECM. thoughts ? Ideas on what to narrow in on before replacing ECM? Could the new pump have changed anything (Direct Indmar replacement, only change was it doesn’t have the line to dump fuel back into tank) , or did I really fry the ecm from my limp back to the dock, and it just was ready to die anyway (even though the week after, before replacing the pump, it would start?). I’m losing my mind here and going to go broke if I have to replace every part unnecessarily !

Hey guys, maybe someone can help me out. I can't seem to find a new blower switch for my dash in my 2000 Sportster. The original is a 4 prong connection but everywhere I've tried around me (Vancouver BC) has only 2 and 3 prong switches.

Hello, While some of my gauges work on my 99 sportster lx with the medallion servo gauges, the speedometer do not read a speed and the gas gauge bounces around. I am do not know what is happening because the gauges have power and the needle turns on ignition but there is no data. I do not have access to the boat for a couple week so I can plan my approach of action. Thanks, Colin

I am just curious about being able to wakesurf on a 1999 Sportster LX. I have ideas on how to do a ballast, but I want to know if it is possible to wakesurf on it? Thanks Colin

Does anyone have or know where I can find a stern light for a 2000 Sportster, the pole had a “step” or “half-moon” at the bottom, where it went into the base.