This might be the wrong place to post this but I'm running out of ideas, I have a 97-98 951cc carb rotax in a 3.5m skrimjet alloy jet boat, I bought this in January after see them over the new years period. I had to fix a few things before taking it out nothing mechanical just the trim nozzle was upside down and the steering arm was to short. No a good start it went really well got up to 85ish kmph. That was good enough for me so I took I back to my shop and started throwing money at it, the engine had receipts for rebuild and a few things in the pump. Long story short I put heaps of racing gear in it to make it a safe boat, I plugged the loom back as it was when I got it, didn't turn over... traced it to the there was no power at the start button, I found power from another switch and got it to turn over. Now we have no spark. I just want to know if there is a way to tell if it's a bad Mpem or another part. I'm from New Zealand people want $1000 for these Mpems wanna be 100% before going down that path. I would look into MSD ignition system if anyone has any knowledge on that. Thanks in advance
1998 951cc carb problems
- Thread starter Izzy 951
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- 951 carb jet boat mpem bypass
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What do you mean by "loom", the plug on the front of the engine? If it was running previously there is no reason to suspect the MPEM just went bad. Do you have a beeper installed? Having a working beeper sure makes life easier when it comes to troublshooting. Sometimes the plug coming from the MPEM gets corroded the plugs must be cleaned. Did you check the fuses? Sometimes the electrical plugs are dirty/corroded and need to be cleaned. I'd suggest downloading a wiring diagram. If you used a jump box on the engine that can damage the MPEM.
I wouldn't buy an MPEM unless I was positive it was bad. Changing random parts on these engines is deep dark hole and gets real expensive with no problems solved. Take your time and methodically track down the problem. Good Luck.
I wouldn't buy an MPEM unless I was positive it was bad. Changing random parts on these engines is deep dark hole and gets real expensive with no problems solved. Take your time and methodically track down the problem. Good Luck.
Yeah the loom as is in all the wires to the guages and to the ignition box, I had to unplug all the Guages and pull them out to remake the dash. No beeper installed, are they a off the shelf part for these motors? One of the pins on the mpem had a little bif of corrosion on it so I clean the pin and tried my best with the plugs. I've tracked from the cdi to the mpem it had the correct resistance 240ohm, had the coil check at a local shop and they checked out, I'll dive into the wiring diagram and try and trace why I lost power. Someone may have done some tig welding on the boat with out disconnecting anything which makes me think it fried a diode or something, has anyone done anything with MSD on these 951s I've heard some old mini race boats has MSD ignition back in the early 2000s.
Now the aluminum welding is a reason to suspect the MPEM or some electrics. The electrical systsem is not that difficult but finding the problems can be tricky. It is like sneaking up on the problem rather than attacking. Too bad you don't have a mate with the same model MPEM.
Here in the states people don't know how good they have it. Sometimes you can buy the whole ski for $200. I'd seriously consider hooking up the beeper. We buy ours from floydbell.com here in the states.
I'd check the plug that hooks into the Magneto. If you have a problem there the MPEM won't do anything and It's easy to forget to when you are hooking everything up. Pay attention to your plugs going into the MPEM and the condition of the MPEM contacts. The wide bladed contacts are where the power comes in. Clean the heck out of them. The small pins in the plugs be careful not to open them up as you clean them. On the mpem itself, I use sandpaper and gently cross sand... "lightly to get any residue off the pins. If you look at the wiring diagram you can determine which wires to chase down first. I'm not sure your ski has the Holder Relay (3-way valve in the diagram) in the back electrical box that fuse cold be blown. If the ski has that relay it would be a good thing to check because if that relay doesn't click... the ski won't do anything. Good Luck !!
Here in the states people don't know how good they have it. Sometimes you can buy the whole ski for $200. I'd seriously consider hooking up the beeper. We buy ours from floydbell.com here in the states.
I'd check the plug that hooks into the Magneto. If you have a problem there the MPEM won't do anything and It's easy to forget to when you are hooking everything up. Pay attention to your plugs going into the MPEM and the condition of the MPEM contacts. The wide bladed contacts are where the power comes in. Clean the heck out of them. The small pins in the plugs be careful not to open them up as you clean them. On the mpem itself, I use sandpaper and gently cross sand... "lightly to get any residue off the pins. If you look at the wiring diagram you can determine which wires to chase down first. I'm not sure your ski has the Holder Relay (3-way valve in the diagram) in the back electrical box that fuse cold be blown. If the ski has that relay it would be a good thing to check because if that relay doesn't click... the ski won't do anything. Good Luck !!
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Thanks for the info, ill look into the beeper but like you said it could be something as simple as a blown fuse or a poor connection. I'll do some more testing and diagnosing during the week. I just pulled the MpeM out of the boat and found a hole in the back, I can see the PCB and looks like someone drew a white cross on the back as if it was modified in some way or deemed faulty, this changes things... it worked before so I hope that isn't the reason for the sudden fault.
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I think whoever made that hole knew something. You do just go in there without a purpose or a plan but it is a bad thing that it was not sealed back up. Look deeply at that area there might be some corrosion causing the components to cross talk. You might be able to clean it up a bit. Sure is nice having a spare component to plug in at times like this. As you say though, the ski ran previously. My concern is that the high frequency of aluminum welding with the components connected may have done some damage. Good Luck with it.
Post some pictures of the project.
Post some pictures of the project.
Exactly, just got off the phone with the guy who did the hole and he is gonna give me the paperwork as to what they did, repaied etc. I know a guy who rebuilds Pcb for TV, radios etc so it could be repaired and sealed properly this time. I'll post pics of it when it comes back from paint. Thanks for your time
Update.. I traced the problem down to what I think is no continuity between pin 2-21 and 3-16 which is the power from the starter button to the coil on the leads, does this mean there is a open circuit in the Mpem as in a blown diode or resistor. It still doesn't explain no spark.
I bridged the wires I mentioned before they plug into the ecu and I can steal power of another plug for the starter button and I can get the Ole girl to turn over but still no spark. This makes me thing something in the Mpem isn't sending signal somewhere. Plugs and pins all looked fine I roughly glazed over the wires and saw no problems. I've hit a dead end to my capabilities anyone got any ideas I could try before I spend 1000 on a new Mpem...
I bridged the wires I mentioned before they plug into the ecu and I can steal power of another plug for the starter button and I can get the Ole girl to turn over but still no spark. This makes me thing something in the Mpem isn't sending signal somewhere. Plugs and pins all looked fine I roughly glazed over the wires and saw no problems. I've hit a dead end to my capabilities anyone got any ideas I could try before I spend 1000 on a new Mpem...
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