MPEM Troubleshooting Help

[lance3556]

I got all my new motor hooked up and wired up but can not get spark to the plugs. I only have 1 box of this style so looking for any recommendations to test the MPEM box. I got the motor and box from Jeremy. Trigger coils resistance test about 240 ohms. I have been thru the wiring and unplugged my reverse set up to ensure that was not a problem. Checked all grounds and they are good when they are supposed to be (ie kill switch when off and box ground is good all the time.) Clean install I hate to tear it out before I even start. 5 wires connected-+12 V pin 2, ground Pin 3, Jumper DESS pin 4/5, kill switch pin 6.

[cory mcleod]

Lance,

Have you compared your wiring to the MPEM diagrams at F500.us? The ground for ignition kill running through two switches used to trip me up sometimes.

[lance3556]

Yes, that is a screen shot of that diagram, I copied the harness I got from Jeremy, so pin outs should be correct, according to the drawing Pin 3 I thought was the circuit ground and Pin 6 the kill switch ground, both tested to be as expected.

[lance3556]

I went wire by wire thru the diagram instead of coping what I got and looks like pin 1 and Pin 12 need 12v, not pin 2. So back to test that today.

[lance3556]

Still no go, when pin 1 is powered , pin 2 see's 12v anyway. The saga will continue, but I do not have any more options for this MPEM. I ordered another off Ebay and will send in for programing and have this one checked.

[lance3556]

Unfortunately I have still not been able to get a spark and start my motor, despite new box, just programmed, New coil, new triggers, new spark plug and again going thru the wiring diagram, try with/without any reverse function, flopped triggers, tried 2 different coils, including 1 new in box, Verified ground to frame, ground to chassis, ground to motor, disconnected kill switch....Any pictures, info or recommendations, keep them coming because I am currently stumped and running out of time. My motor is mounted on rubber with a rubber bumper on a torque arm so I ran a ground wire to the frame from the motor, but it all test good. I had about 12 VAC on MPEM out to coil when disconnected from coil and MPEM powered up, but nothing when connected to the coil. Not rocket science, but I must be missing something,

[cory mcleod]

Make sure that the kill circuit is open to run and closed to ground to stop. Not sure what type of kill switch you have but they do fail sometimes and I've always found the wiring counterintuitive.

[lance3556]

Thanks, I currently have it disconnected completely since I started having issues.

[lance3556]

So the issue has not yet been resolved, if any body has a picture of their connections or diagram of how they wired up this type of MPEM, let me know. It is a 12 pin 2003/204 360w type MPEM. I am going to skip the reverse function for now in hopes of getting a spark going.

I have 2 boxes I just got back from BRP and he believes they should work fine. I will be trying again this weekend to re-wire as needed and hope I can get it to work properly.

[lance3556]

Finally resolved this this weekend. Turns out the BRP relay is a critical purpose in the circuit. I was trying to power up the MPEM straight from the battery, and that does not work for some reason. Have to start the car with the voltage regulator powering the MPEM, then you can switch it over to battery power/charging. I was un-familiar with that little tidbit of key knowledge. I am guessing that if you apply to much voltage before the motor is running, the device goes into some programing or other mode and will not cycle the ignition. I installed a switch inplace of the relay so I can start the car, then switch over to charge the battery. Thanks for the tips everybody that helped trying to resolve this.

[f500racer]

Hooray

I hope it runs well and provides new found power.

Jeremy Swank

[mmi16]

Finally resolved this this weekend. Turns out the BRP relay is a critical purpose in the circuit. I was trying to power up the MPEM straight from the battery, and that does not work for some reason. Have to start the car with the voltage regulator powering the MPEM, then you can switch it over to battery power/charging. I was un-familiar with that little tidbit of key knowledge. I am guessing that if you apply to much voltage before the motor is running, the device goes into some programing or other mode and will not cycle the ignition. I installed a switch inplace of the relay so I can start the car, then switch over to charge the battery. Thanks for the tips everybody that helped trying to resolve this.

The engine should not require a connection to a battery to run. The magneto supplies all the juice needed for the engine to operate, witness the operation of the recoil starter.

Ran a race at Pocono one year, my dash went dark on the Pace Lap. Ran the whole race, the ground wire for the battery broke. The only thing the battery actually POWERED was the starter and the dash - once the engine is running the magneto gives it all it needs. From impound since the starter didn't work, the recoil fired it up to get back to my paddock space.

[lance3556]

The engine should not require a connection to a battery to run. The magneto supplies all the juice needed for the engine to operate, witness the operation of the recoil starter.

That is a correct statement, but if you like to have an integrated system and a battery that gets charged from the voltage regulator, and you have a 2003 box with a 12 pin connector (not a direct connection to the coil in the stater), don't directly hook a battery to it. I lost a lot of sleep over this tidbit of information and just sharing the wealth of knowledge I gained. I am going to try and hook my starter up to the MPEM and get reverse working sometime this year, but now I have some racing to do first

[lance3556]

I only found this after I resolved my issue, but it was posted in 2015 at the other site and it did not say why the relay was important. I had read it but thought because they were using a sled harness, they would use what was on the harness.

[Tom Grossmann]

Glad you got it running..........seeing as I took all of your running motors.